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File:Testcase presentation Günz.pdf

2021-03-17T17:02:43Z

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File:Testcase presentation Freudenau.pdf

2021-03-17T16:35:16Z

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File:Testcase presentation Altheim.pdf

2020-11-04T10:45:17Z

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File:Testcase presentation Altusried.pdf

2020-11-04T10:41:30Z

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Günz test case

2020-10-23T14:55:30Z

LB: /* About the hydropower plants */

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 60 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by flood peaks in winter due to snow melting and some flood peaks in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 550 kW at Höselhurst, 520 kW at Wattenweiler, 720 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.4 - 3.1 GWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [https://wasserkraft.lew.de/lew-wasserkraft]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The LEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical simulations of flow and habitat conditions in the fishway

=Results=
In February 2018 and 2019, gravel was implemented as a spawning ground in 4 of the 5 fish passes of LEW Wasserkraft at the river Günz. Afterwards the spawning activities were monitored on a daily basis. A special focus was put on the nase (Chondrostoma nasus), which was very common in former times in the Günz, like in the “barb region” of most rivers in Bavaria.

The nase was selected as a success indicator for the design of the spawning grounds, because their spawning activities depend on the water temperature.

In 2018 the successful spawning of the nase could be verified at the fish pass in Wattenweiler all over the area, where new gravel was implemented. Many eggs were found in that section, just a view days after the gravel was inserted. In the other fish passes downstream, no eggs were found in that year. This was probably because the spawning season of the nase was very early in spring 2018 and the adding of gravel happened too late for that. In 2019 spawning nase were found in all fish passes with ponds with new gravel, but also in ponds where the gravel from the first year was mechanically re-allocated. While the coarse substrates of the initial situation were also used for spawning (nase and dace (Leuciscus leuciscus), the numbers showed that the nase clearly prefers the ponds with new gravel.

The gravel ponds, prepared in 2018, had a relatively strong grade of colmation in 2019, which means that the gaps between the gravel was filled with fine sediments. However, the gravel still was still loose enough for the fish to re-allocate it when preparing their spawning pits. The colmation of the substrate is caused by the static water flow from the main river, which is common in all fish passes. A natural dynamic, in terms of a re-allocation of the bed load, is missing. As the fish were found to prefer new, clean gravel, this results in an expected very good functioning of the new spawning grounds for about two year.

A recommendation from these findings is therefore to include the option to “irrigate” the ponds, when planning the construction of a new fish pass. This could be achieved, for example, with additional pipes that cross the dam. They offer the opportunity to multiplicate the water flow temporarily, enabling a certain nature-like dynamic with a re-allocation of the substrates.

To conclude, the preparation of spawning grounds in existing fish passes by inserting gravel, was a great success, also in terms of a good cost-benefit-ratio.

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg| The hydropower plant Ellzee on the river Günz (source: LEW).
Gunz_hosenhurst_hpp.jpg|The hydropower plant Hösellhurst with fish pass on the river Günz (source: Olav König).
Gunz_oberegg_hpp.jpg|The diversion weir at Deisenhausen, upstream of the hydropower plant Oberegg (source: LEW).
Günz-layout.png|Location of the 5 test case hydropower plants on the Günz river (source: LEW).
HPP-Ellzee-nature-like-fishway.jpg|View of the hydropower plant and nature like fishway at Ellzee (source: Olav König).
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river (source: Nicole Kalinowski, IBF Umwelt).
</gallery>

Altusried test case

2020-10-21T14:31:39Z

LB:

[[Category:Test cases]]
{{Fact box for Altusried}}
{{Relevant SMTDs for Altusried}}

=Introduction=
The river Iller is located in the far south-western part of Germany. It flows into the river Danube near the city Ulm. The river Iller originates from the confluence of the three rivers Stillach, Breitach and Trettach near the city Oberstdorf in the “Allgäuer Alps”, south Germany.

It’s catchment area has a size of 2152 km2. The HPP Altusried is the first HPP of a power plant chain of five HPPs that are operated by the LEW Wasserkraft GmbH. The last HPP of the LEW Wasserkraft GmbH is near Lautrach. In the downstream area of the LEW Wasserkraft GmbH HPP chain there are an additional 8 HPPs.

The hydrology of the Iller is characterized by sustained flows in winter, high water levels in spring due to snow melting and low water periods from August to October. At Altusried, the main Test Case HPP at the Iller, the mean interannual discharge is 46.6 m3/s (level Kempten).

=About the hydropower plants=
The HPP at Altusried is a run-of-river HPP with an installed capacity of 4 MW and a mean annual output of 30 million kWh. The HPP has two Kaplan turbines, each with a flow rate of 50 m3/s and a drop height of 9 m. The hydropeaking operation mode has been minimized since 2014.

===Layout===
There is a big reservoir in the upstream area of the Hydropower plant. In the downstream area of the HPP the river Iller is still flowing. After a free flowing area of around 1500m impoundment by the next reservoir starts. The LEW Wasserkraft GmbH has built a fish bypass channel around the HPP in 2015. It is 700 m long and has a mean flow of 1 m3/s.

===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft GmbH is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [[https://wasserkraft.lew.de/lew-wasserkraft Read more.]]

===Pressures on the water body's ecosystem===
The main pressures on the water body are morphology and hydrology. The formerly high pressure for river continuity, has been reduced through a fish bypass channel which has been built in 2014 - 2015.

The pressures are mainly caused by morphological issues which are results of the HPP. There is a lack of important habitats such as juvenile habitats, spawning habitats and the reophilic interstitial. The LEW Wasserkraft GmbH is working on this challenges with two restauration programmes, the Illerstrategie 2020 and the EU-found program ISOBEL.

=Test case topics=
===Fish population===
The river is dominated by reophilic and potamodroumous species. The main species are greyling, barbel, nase, brown trout, danube salmon, chub and several small fish species. In the reservoir basins, typical lake fish species such as tench, rudd, carp and pike can also be found. Since 2016 the LEW together with the University of Augsburg are investigating what types and numbers of fish using the fish passes constructed by LEW on the 5 hydropower plants of (from downstream to upstream) Lautrach, Maria Steinbach, Legau, Fluhmühle and Altusried. Every fish swimming through a fish pass is caught in a catch construction upstream in the fish pass. The catch construction (called counting pool) is evaluated nearly daily and fish that are caught are measured (length) and marked. The mark is a blue dot on their belly near the left or right pectoral, pelvic or caudal fin, depending on the fish ladder they were passing. In this way, migratory route of marked fish can be evaluated.

===Migration devices===
A fish bypass channel has been built 2014 - 2015. It has a length of 700 m and a flow of 1 m3/s. To also fulfill a compensation habitat function, juvenile and spawning habitats have been built into the fish-bypass channel.

===Downstream migration===
Downstream migration is possible during weir overflow or while the bottom outlets are opened. Thrash racks in front of the turbines, with a spacing of 20 mm between the racks, prevent fish from swimming into the turbines.

===Upstream migration===
The upstream migration is possible through the fish bypass channel. Within a monitoring programm, over 7000 fish have been documented using the fish bypass channel for upstream migration within 3 years.

===E-flow===
The minimum outflow of the turbines is 9.0 m3/s, during the whole year. This regulation is part of the “Illerstrategie 2020” of the LEW Wasserkraft GmbH. It is based on the natural minimum flow of the river Iller.

=Research objectives and tasks=
At the Test Case Altusried, the ways fish are finding the downstream entry of fish bypass channels is being studies. For this, fish tagging and [[acoustic telemetry]] is used to follow the ways of fish into the bypass channel. Additionally, Flow measurements are conducted in the outflow area of the fish ladder. This information is used to develop an agent-based fish movement model incorporated in the fish habitat simulation model [[CASiMiR]]. The research work is implemented by LEW, SJE, INBO, and TUT.

===Research tasks===
The research tasks and field studies conducted at the HPP on the river Iller are:

* Telemetry studies
* Velocity fluctuation measurements using the Lateral Line Probe
* 2D hydrodynamic model and CASiMiR migration model
* Population and habitat analysis

=Results=
===Population and habitat analysis===
The impact of the newly created fish-bypass channels and habitat measures have been monitored with electro fishing campaigns from 2016 – 2019 that are carried out twice a year on a length of 1500m downstream at both shorelines against the flow and in the middle of the river with the flow. The results of the electro fishing campaigns indicate the presence of all characteristic fish species in the Iller and thus an improvement of the formerly poor fish community status. Especially barbel, Danube salmon, grayling, chub and brown trout were caught in gratifying numbers, both in juvenile and adult stages. In spring 2018 even 6 young Danube Salmon were found. Only the population of nase is still in a rather poor condition.

===Acoustic 2D telemetry fish tracking===
The Vemco Positioning System (VPS) was applied to track fish swimming behaviour in 2D. Through the fish telemetry study, 15 million fish positions of 47 wild fish, 25 grayling and 22 barbel were collected. The tagged fish stayed in the VPS network between 2 and 92 days, whereby barbel resided on average for longer in the area than grayling. The fish detections of the hydrophones in the fish pass already indicate that 12 tagged grayling and 8 tagged barbel found the entrance of the fish ladder at least once and swum up at least half way. Of these, 10 grayling and 6 barbel then also found their way upstream into the counting pool.

===Hydrodynamic modelling===
A hydrodynamic model was set up using Hydro-As_2D to derive flow velocities and water depth as input parameter for the developed migration model. To cover the wide flow range that can occur during migration periods, the flow scenarios considered in the model range from 10 m3/s to 80 m3/s. The results from the hydrodynamic model show that for a low flow situation with 10 m3/s the flow velocities are increased close to the area of the fish ladder outlet. Usually this zone of increased flow velocities is considered to have a guiding function for fish searching the fish ladder entrance. But even for the low flow situation the increased flow velocities can only be detected in the direct vicinity of the fish ladder entrance. For higher flows the extension of the higher flow velocity area is much less distinct.

===Migration model===
An extension of the habitat simulation system [[CASiMiR]] is being developed with input from the Test Cases. This new [[Agent based model|CASiMiR-Migration model]] is designed to simulate the migration behaviour of fish. For Altusried, the model has been applied to a lower flow velocity threshold of 0.15 m/s and an upper threshold of 1.5 m/s. When positioning the virtual fish equally over the river width in the lower part of the river stretch 10% of fish find the fish ladder entrance with flow velocities of 10 m3/s, 7% with 20 m3/s and 5 % with 60 m3/s in the river. I.e. the higher the flow in river the less distinct is the attraction flow when considering only flow magnitude and direction. By a first evaluation of the fish tracks it is already clear that the percentage of fish finding the fish ladder entrance is much higher than these values. This indicates that the current model has to consider additional parameters as mentioned before.

=Gallery=
<gallery mode=packed>
Günz (C)flussbauiC VillachAustria3.jpg|Areal view of the hydropower plant Altusried (picture rights: iCFlussbau, Villach Austria)
Installing acoustic receivers (black cylinder) in the Iller (c)Ine Pauwels, INBO.jpg|Installation of acoustic receivers in the Iller (picture rights: Ine Pauwels, INBO
Fieldwork team (c) Ine Pauwels INBO.jpg|The team conducting the fieldwork at Altusried (picture rights: Ine Pauwels, INBO)
Downstream view of Iller (c) Ine Pauwels INBO.jpg|View of the Iller downstream of the HPP with the fishpass (picture rights: Ine Pauwels, INBO)
</gallery>

File:Downstream view of Iller (c) Ine Pauwels INBO.jpg

2020-10-21T14:30:11Z

LB:

Downstream view of the Iller with the fishpass

File:Fieldwork team (c) Ine Pauwels INBO.jpg

2020-10-21T14:27:42Z

LB:

The fieldwork team conducting the telemetry research at the HPP Altusried

File:Installing acoustic receivers (black cylinder) in the Iller (c)Ine Pauwels, INBO.jpg

2020-10-21T14:25:22Z

LB:

To ancor the acoustic receivers (black cylinder) in the river bed they are mounted onto metal pyramids which are then placed on their location in the river with a boat.

File:Günz (C)flussbauiC VillachAustria3.jpg

2020-10-21T14:22:17Z

LB:

Areal view of the hydropower plant Altusried and fishpass.

Altusried test case

2020-10-21T14:18:45Z

LB: /* Acoustic 2D telemetry fish tracking */

Altheim test case

2020-10-21T14:02:25Z

LB:

[[Category:Test cases]]
{{Fact box for Altheim}}
{{Relevant SMTDs for Altheim}}
=Introduction=
The river Isar, located in the south of Germany, is an Alpine river. It flows from its source in Austria at 1600 m above sea level through the Alps, pre-alpine moorlands and through the city of Munich before entering the Danube river near Deggendorf at 300 m above sea level. With a length of 260 km it is the fourth largest river in Bavaria and the second most important tributary of the Danube in Germany.

The catchment area of the Isar covers 8960 km2 in the Alps and the Karwendel mountains. The Isar is generally divided into three sections: the Upper Isar, the Middle Isar and the Lower Isar. The Test Case hydropower plant Altheim is located in the Lower Isar, at km 67.2, near the town Altheim. Downstream of the Test Case, 7 additional hydropower plants are located along the Isar.
The section of the Isar that relates to the Test Case Altheim has a catchment area of 88.2 km2 and is about 73 km long. It has an intern-annual discharge of 163 m3/s. Typically the discharge characteristics show high flows and fast floods in spring time during snow melt and rather low flows in winter. It is classified as a waterbody with poor ecological status.

=About the hydropower plant=
The hydropower plant at Altheim, commissioned in 1951, is a block-type hydropower plant and part of a chain of power plants in the Isar. The catchment area of this river stretch is about 7.908 km². It has an installed capacity of 17.8 MW and a mean annual output of 91.4 GWh. The plant has a gated weir with 4 bays located on the right of the power house and a head storage volume of 1,980,000 m3.

The normal operating level is at 384.00 m above sea level, in swelling operation it can be lowered by 1.00 m. On average, there are 2 peaks per day, where the flow changes roughly between 50 m3/s and 170 m3/s with ramps of about 100 m3/s per hour or a change of water level between +45 cm/h to - 30 cm/h.
===Layout===
The area around the power plant is dominated by commercial and living areas on the left side and a popular local recreation area with lakes for swimming on the right side, as well as a sewage treatment plant in Altheim.
===The Operator: Uniper SE===
Uniper Hydro Germany operates 109 hydroelectric power plants, containing run of river plants, storage and pumped storage. Alongside the rivers Lech, Isar, Danube and Main more than 1300 kilometres are used for the production of clean electricity. In close cooperation with regional stakeholders (politicians, authorities, NGOs) Uniper takes over responsibility to protect civil areas from floods, but also to protect the environment. [https://www.uniper.energy/ Read more.]

=Pressures on the water body's ecosystem=
The main pressures on the water body are nutrients, river specific pollutants, agricultural production and hydromorphological changes. These are on the one hand related to agriculture on the other hand the hydromorphology is impacted by the sequence of hydropower plants and their related ponds. Moreover, the chemical pressure (especially mercury) cannot be neglected.

=Test case topics=
===Fish population===
The relevant water body is located in the barbel region (epipotamal) and is therefore dominated by potamodromous species. During electro fishing in autumn 2007, 43 fish species could be identified, containing 35 indigenious species, 27 red listed species and 9 FFH species, which were mainly rheophile fish. Out of those, six were endemic species: Hucho hucho, Rutilus pigus, Gobio albipinnatus, Gymnocephalus schraetser, Zingel zingel and Zingel streber.
===Upstream migration===
The dimensioning criteria for the upstream migration facility, which was built in 2015, were the fish species Barbus barbus and Hucho hucho. The fish pass consists of a rough channel for the downstream connection at the entry of the fish pass. It is located on the right-hand side 300 m downstream of the power plant. An existing ditch has been used to facilitate the fish passage over 4.5 km and for providing new hydromorphological structures and habitats in the fish pass. Upstream, a vertical slot connects the nature-like fish pass to the river. This migration facility is always supplied with a minimum flow of 450 l/s which can be extended to up to 800 l/s.
===E-flow===
HPP Altheim is one HPP in a chain of hydropower plants. Usually a minimum flow of 40 m3/s is operated, a full stop of machines is a rare exception. For own purposes, one machine for station supply must always be operated with a minimum of 11.7 m3/s. Although the connected small stream Längenmühlbach has an agreed minimum e-flow of 3.2 m3/s all year, it is not within the scope of the Altheim Test Case within FIThydro.

=Research objectives and tasks=
Within the project, the fish pass at the plant shall be evaluated regarding the effectiveness of its existing hydromorphological structures. Both, the variation of the original structures to the current status as well as the usage of the existing habitats by fish shall be evaluated. Based on the results a concept for improved hydromorphological measures shall be developed under the consideration of acceptance by fish and expenses for maintenance. Moreover, the experiences with the maintenance of the nature-like fish passes shall be evaluated. This will be relevant for further decisions on the implementation of upstream migration measures.
===Research tasks===
The research tasks and field studies conducted at the Altheim HPP are:

* Mapping the availability of habitat structures and analysing their added value for migrating fish
* Evaluating the maintenance costs of a nature-like fish pass
=Results=
Over a total length of about 1.5 km of the natural fish pass 37 different habitat structures have been implemented. The structures mainly consist of dead wood and spawning gravel and were constructed as spawning habitats, juvenile habitats or shelter but also to generally increase the variability in flow conditions. The value of these structures was evaluated from October 2019 to May 2020.

To evaluate the potential ecological value of the measures, five habitat structures were selected and examined by using the underwater cameras „Rollei 525“. Three cameras were placed around the habitat structures and three were placed at the other, unaltered bank. This approach allowed to compare and assess the fish density between the two sides. Furthermore it was possible to compare the five habitat structures with each other on the basis of predefined parameters and to frame potential differences regarding fish density and fish species.

The results show that the habitat structures provide a significant ecological benefit. They offer habitats especially for small fish species such as schneider (Alburnoides bipunctatus) to support their population. Especially the variability between fast flowing areas and flat, flow-reduced sections support the availability of specific habitats for different species. Also it turned out that there are major differences between the habitat structures regarding fish density and the number of fish species. This is probably caused by seasonal variation and preferences, abiotic factors as well as the location and type of habitat structure.

The high velocity and cool water temperature in the fish pass generally support the establishment of a sustainable grayling population. This fact is especially important regarding the threatened status of the grayling and the lack of habitats in the main river Isar. It shows the high water quality and good habitat availability of the fish pass. The fish pass turned also out to be a suitable habitat for ground oriented fish species such as barbel gudgen, zingel or European bullhead.

The criteria for habitat structures adding value to the fish pass do highly vary with the species targeted at. Structures with good flow conditions and clean gravel substrate in combination with the low water temperature showed excellent results for the target species of river Isar. Also the position of the structure is important to avoid deposition of fine sediments and also over a variety of water depths.

The maintenance effort does mainly increase with the length of the fish pass but not with the implementation of the habitat structures. It is important that the fish pass contains the necessary maintenance infrastructure such as ways along to be used by cars and heavy machines to make sure the maintenance works can be done properly. The habitat structures are expected to need a proper refurbishment after a longer time period than analysed in within the project.

=Gallery=
<gallery mode=packed>
altheim_overview.jpg|Aerial view of Altheim dam, power plant, and reservoir (source: Uniper).
altheim_natural_fishway.jpg|Entrance to the nature-like fishway at Altheim (source: Uniper).
altheim_layout.png|Layout of the Altheim powerplant and the surrounding area (source: google maps, Uniper).
altheim_natural_fishway_downstream.jpg|View of the Altheim nature-like fishway from downstream (source: Uniper).
altheim_migration_layout.jpg|Layout of the fish migration system at the hydropower plant Altheim (source: google maps, Uniper).
Altheim structure 1.jpg|thumb|Implementation of rocks to vary flow conditions (source: Uniper.
Altheim structure 2.jpg|thumb|Relocation of gravel as spawning habitat (source: Uniper).
Altheim underwater.jpg|thumb|Underwater picture of fish at one of the structures (source: Uniper).
</gallery>

Freudenau test case

2020-10-21T14:00:10Z

LB:

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second largest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km². The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m³/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. The group generates around 95 % of its electricity from renewable energy, primarily from hydropower. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream is fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 8-10 cm per year. The amount of added gravel is about 235.000 m³ per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=

'''Feasibility study'''

Because the study area is characterized by fast flow conditions and increased sound reflection due to riprap and shallow areas around the fish pass entry, a feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019.
The study resulted in low tag detections in the vicinity of the hydropower plant but satisfying results downstream the entrance to the fish pass. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. This results in a limitation of the actual telemetry study to the fish pass and an area of 500 – 800m downstream of its entrance.

'''2D Telemetry study'''

To investigate the migration routes adult nase take during spawning season when trying to find the fish pass entry, a 2D telemetry study was conducted in April 2020. Hydroacoustic telemetry array was established in the Danube downstream the entrance to the fish pass. Additionally, radio tracking was used to observe tagged adult nase beyond the boundaries of the hydroacoustic surveillance.
During the main study period the discharge varied between 1,200 m³/s and 1,700 m³/s. The turbined water is directed to the left side of the river channel and creates a strong current right in front of the entry to the fish pass. The morphology in the area is very heterogenous with water depths varying from 2 m to 10 m (Figure 1).

13 hydrophones of the type WHS3250 (provider LOTEK) were strategically placed in the study area to cover the left half of the riverbed approximately 100 m upstream and 500 m downstream of the entry to the fish pass.For the study, 35 male nase, previously caught in the lower section of fish pass of the HPP Freudenau, were tagged and released approximately 1 km downstream of the hydrophone array.

Fish positions were recorded during the period of April 15th to May 7th 2020, resulting in 13 fish swimming path with 3000 - 17500 location points each after data aggregation.

'''Numerical model'''

In order to analyses potential cues for orientation, a numerical model of the fish pass entrance and downstream area of the HPP has been set up using FLOW3D. The applied numerical model solves the hydrodynamic (Fig.2), temperature (Fig. 3) and chemical spatial (Fig. 4) distribution for two scenarios that reflect the conditions of the field measurement campaign.

As result the spatial pressure, velocity, temperature and tracer fields are available. The numerical result were be combined with the fish swimming path obtained from the telemetry study. Since the telemetry study was carried out during relative low flow conditions the discharge through the HPP varies between 1050 and 1400 m³/s. Additionally one has to point out that for these discharges the distribution of the discharge within the HPP varies and influences the tailwater characteristic visibly.

The temperature field within the numerical model is only influenced by the water temperature of the fish pass. Even the fish pass is fed with Danube water the interaction with the groundwater is much higher und therefore influences the water temperature in there. Records of BOKU, which were taken together with the telemetry study, show a temperature difference between Danube and fish pass of about +- 0.6 °C, varying over the day. During night the fish pass was colder compared to the Danube, while the ratio changed during the day. These dynamics in temperature is not considered by the numerical simulation. But, the numerical results show how far the temperature influence extends.

<gallery mode=packed>
Freudenau Fig. 1 Contour map of study area rights BOKU, image source, Google Earth.png|Fig. 1 Contour map of study area downstream of the HPP Freudenau (Picture rights: BOKU, image source: Google Earth).
Freudenau Fig 2 Velocity fields soure TUM.png|Fig. 2 Velocity field of tailwater of HPP Freudenau with a fish track (black points). (Picture rights: T. Liepert, TUM).
Freudenau Fig. 3 Temperature fields of tailwater source TUM.png|Fig. 3 Temperature field of tailwater of HPP Freudenau with a fish track (black points). (Picture rights: T. Liepert, TUM)
Freudenau Fig 4 Chemical tracer field of tailwater source TUM.png|Fig. 4 Chemical (tracer) field of tailwater of HPP Freudenau with a fish track (black points). (Picture rights: T. Liepert, TUM)
</gallery>

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau hydropower plant (source:Verbund).
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine at hydropower plant Freudenau (source: Verbund).
fredenau_fishway.jpg|Nature-like fishway at Freudenau (source: Verbund).
Layout-2-Freudenau_Verbund.png|Layout of the hydropower plant Freudenau (source: Verbund).
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of the hydropower plant Freudenau (source: Verbund).
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP and its different sections (source: Verbund).
fredenau_adding_sediments.jpg|Sediment is being added downstream of the hydropower plant Freudenau (source: Verbund).
</gallery>

File:Freudenau Fig 4 Chemical tracer field of tailwater source TUM.png

2020-10-21T13:57:58Z

LB:

Chemical (tracer) field of tailwater of HPP Freudenau with a fish track (black points) created using FLOW3D.

Freudenau test case

2020-10-21T13:32:19Z

LB: /* Results */

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second largest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km². The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m³/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. The group generates around 95 % of its electricity from renewable energy, primarily from hydropower. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream is fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 8-10 cm per year. The amount of added gravel is about 235.000 m³ per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=
[[File:Freudenau Fig. 1 Contour map of study area rights BOKU, image source, Google Earth.png|thumb|right|Fig. 1 Contour map of study area downstream of the HPP Freudenau (Picture rights: BOKU, image source: Google Earth)]]
[[File:Freudenau Fig 2 Velocity fields soure TUM.png|thumb|right|Fig. 2 Velocity field of tailwater of HPP Freudenau with a fish track (black points). (Picture rights: TUM)]]
[[File:Freudenau Fig. 3 Temperature fields of tailwater source TUM.png|thumb|right|Fig. 3 Temperature field of tailwater of HPP Freudenau with a fish track (black points). (Picture rights: TUM)]]
'''Feasibility study'''

Because the study area is characterized by fast flow conditions and increased sound reflection due to riprap and shallow areas around the fish pass entry, a feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019.
The study resulted in low tag detections in the vicinity of the hydropower plant but satisfying results downstream the entrance to the fish pass. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. This results in a limitation of the actual telemetry study to the fish pass and an area of 500 – 800m downstream of its entrance.

'''2D Telemetry study'''

To investigate the migration routes adult nase take during spawning season when trying to find the fish pass entry, a 2D telemetry study was conducted in April 2020. Hydroacoustic telemetry array was established in the Danube downstream the entrance to the fish pass. Additionally, radio tracking was used to observe tagged adult nase beyond the boundaries of the hydroacoustic surveillance.
During the main study period the discharge varied between 1,200 m³/s and 1,700 m³/s. The turbined water is directed to the left side of the river channel and creates a strong current right in front of the entry to the fish pass. The morphology in the area is very heterogenous with water depths varying from 2 m to 10 m (Figure 1).

13 hydrophones of the type WHS3250 (provider LOTEK) were strategically placed in the study area to cover the left half of the riverbed approximately 100 m upstream and 500 m downstream of the entry to the fish pass.For the study, 35 male nase, previously caught in the lower section of fish pass of the HPP Freudenau, were tagged and released approximately 1 km downstream of the hydrophone array.

Fish positions were recorded during the period of April 15th to May 7th 2020, resulting in 13 fish swimming path with 3000 - 17500 location points each after data aggregation.

'''Numerical model'''

In order to analyses potential cues for orientation, a numerical model of the fish pass entrance and downstream area of the HPP has been set up using FLOW3D. The applied numerical model solves the hydrodynamic, temperature and chemical spatial distribution for two scenarios that reflect the conditions of the field measurement campaign.

As result the spatial pressure, velocity, temperature and tracer fields are available. The numerical result were be combined with the fish swimming path obtained from the telemetry study. Since the telemetry study was carried out during relative low flow conditions the discharge through the HPP varies between 1050 and 1400 m³/s. Additionally one has to point out that for these discharges the distribution of the discharge within the HPP varies and influences the tailwater characteristic visibly (see Fig. 2).

The temperature field within the numerical model is only influenced by the water temperature of the fish pass. Even the fish pass is fed with Danube water the interaction with the groundwater is much higher und therefore influences the water temperature in there. Records of BOKU, which were taken together with the telemetry study, show a temperature difference between Danube and fish pass of about +- 0.6 °C, varying over the day. During night the fish pass was colder compared to the Danube, while the ratio changed during the day. These dynamics in temperature is not considered by the numerical simulation. But, the numerical results show how far the temperature influence extends (see Fig. 3).

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau hydropower plant (source:Verbund).
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine at hydropower plant Freudenau (source: Verbund).
fredenau_fishway.jpg|Nature-like fishway at Freudenau (source: Verbund).
Layout-2-Freudenau_Verbund.png|Layout of the hydropower plant Freudenau (source: Verbund).
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of the hydropower plant Freudenau (source: Verbund).
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP and its different sections (source: Verbund).
fredenau_adding_sediments.jpg|Sediment is being added downstream of the hydropower plant Freudenau (source: Verbund).
</gallery>

=Relevant Literature=

File:Freudenau Fig. 3 Temperature fields of tailwater source TUM.png

2020-10-21T12:52:37Z

LB:

Temperature field of tailwater of HPP Freudenau with a fish track (black points) created using FLOWD3D.

File:Freudenau Fig 2 Velocity fields soure TUM.png

2020-10-21T12:18:08Z

LB:

Velocity field of tailwater of HPP Freudenau with a fish track (black points) created using FLOW3D.

File:Freudenau Fig. 1 Contour map of study area rights BOKU, image source, Google Earth.png

2020-10-21T11:57:56Z

LB:

Study area a contour map, generated using a sonar combined with an Active Imaging 3-in-1 transducer device, showing the water depth in the research area downstream of the HPP.

Günz test case

2020-10-21T10:36:38Z

LB:

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 60 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by flood peaks in winter due to snow melting and some flood peaks in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 450 kW at(Höselhurst and Wattenweiler, 600 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.8 – 3.7 millions kWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [https://wasserkraft.lew.de/lew-wasserkraft]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The LEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical simulations of flow and habitat conditions in the fishway

=Results=
In February 2018 and 2019, gravel was implemented as a spawning ground in 4 of the 5 fish passes of LEW Wasserkraft at the river Günz. Afterwards the spawning activities were monitored on a daily basis. A special focus was put on the nase (Chondrostoma nasus), which was very common in former times in the Günz, like in the “barb region” of most rivers in Bavaria.

The nase was selected as a success indicator for the design of the spawning grounds, because their spawning activities depend on the water temperature.

In 2018 the successful spawning of the nase could be verified at the fish pass in Wattenweiler all over the area, where new gravel was implemented. Many eggs were found in that section, just a view days after the gravel was inserted. In the other fish passes downstream, no eggs were found in that year. This was probably because the spawning season of the nase was very early in spring 2018 and the adding of gravel happened too late for that. In 2019 spawning nase were found in all fish passes with ponds with new gravel, but also in ponds where the gravel from the first year was mechanically re-allocated. While the coarse substrates of the initial situation were also used for spawning (nase and dace (Leuciscus leuciscus), the numbers showed that the nase clearly prefers the ponds with new gravel.

The gravel ponds, prepared in 2018, had a relatively strong grade of colmation in 2019, which means that the gaps between the gravel was filled with fine sediments. However, the gravel still was still loose enough for the fish to re-allocate it when preparing their spawning pits. The colmation of the substrate is caused by the static water flow from the main river, which is common in all fish passes. A natural dynamic, in terms of a re-allocation of the bed load, is missing. As the fish were found to prefer new, clean gravel, this results in an expected very good functioning of the new spawning grounds for about two year.

A recommendation from these findings is therefore to include the option to “irrigate” the ponds, when planning the construction of a new fish pass. This could be achieved, for example, with additional pipes that cross the dam. They offer the opportunity to multiplicate the water flow temporarily, enabling a certain nature-like dynamic with a re-allocation of the substrates.

To conclude, the preparation of spawning grounds in existing fish passes by inserting gravel, was a great success, also in terms of a good cost-benefit-ratio.

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg| The hydropower plant Ellzee on the river Günz (source: LEW).
Gunz_hosenhurst_hpp.jpg|The hydropower plant Hösellhurst with fish pass on the river Günz (source: Olav König).
Gunz_oberegg_hpp.jpg|The diversion weir at Deisenhausen, upstream of the hydropower plant Oberegg (source: LEW).
Günz-layout.png|Location of the 5 test case hydropower plants on the Günz river (source: LEW).
HPP-Ellzee-nature-like-fishway.jpg|View of the hydropower plant and nature like fishway at Ellzee (source: Olav König).
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river (source: Nicole Kalinowski, IBF Umwelt).
</gallery>

Günz test case

2020-10-21T10:31:44Z

LB: /* Results */

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 60 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by flood peaks in winter due to snow melting and some flood peaks in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 450 kW at(Höselhurst and Wattenweiler, 600 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.8 – 3.7 millions kWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [https://wasserkraft.lew.de/lew-wasserkraft]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The LEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical simulations of flow and habitat conditions in the fishway

=Results=
In February 2018 and 2019, gravel was implemented as a spawning ground in 4 of the 5 fish passes of LEW Wasserkraft at the river Günz. Afterwards the spawning activities were monitored on a daily basis. A special focus was put on the nase (Chondrostoma nasus), which was very common in former times in the Günz, like in the “barb region” of most rivers in Bavaria.

The nase was selected as a success indicator for the design of the spawning grounds, because their spawning activities depend on the water temperature.

In 2018 the successful spawning of the nase could be verified at the fish pass in Wattenweiler all over the area, where new gravel was implemented. Many eggs were found in that section, just a view days after the gravel was inserted. In the other fish passes downstream, no eggs were found in that year. This was probably because the spawning season of the nase was very early in spring 2018 and the adding of gravel happened too late for that. In 2019 spawning nase were found in all fish passes with ponds with new gravel, but also in ponds where the gravel from the first year was mechanically re-allocated. While the coarse substrates of the initial situation were also used for spawning (nase and dace (Leuciscus leuciscus), the numbers showed that the nase clearly prefers the ponds with new gravel.

The gravel ponds, prepared in 2018, had a relatively strong grade of colmation in 2019, which means that the gaps between the gravel was filled with fine sediments. However, the gravel still was still loose enough for the fish to re-allocate it when preparing their spawning pits. The colmation of the substrate is caused by the static water flow from the main river, which is common in all fish passes. A natural dynamic, in terms of a re-allocation of the bed load, is missing. As the fish were found to prefer new, clean gravel, this results in an expected very good functioning of the new spawning grounds for about two year.

A recommendation from these findings is therefore to include the option to “irrigate” the ponds, when planning the construction of a new fish pass. This could be achieved, for example, with additional pipes that cross the dam. They offer the opportunity to multiplicate the water flow temporarily, enabling a certain nature-like dynamic with a re-allocation of the substrates.

To conclude, the preparation of spawning grounds in existing fish passes by inserting gravel, was a great success, also in terms of a good cost-benefit-ratio.

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg| The hydropower plant Ellzee on the river Günz (source: LEW).
Gunz_hosenhurst_hpp.jpg|The hydropower plant Hösellhurst with fish pass on the river Günz (source: Olav König).
Gunz_oberegg_hpp.jpg|The diversion weir at Deisenhausen, upstream of the hydropower plant Oberegg (source: LEW).
Günz-layout.png|Location of the 5 test case hydropower plants on the Günz river (source: LEW).
HPP-Ellzee-nature-like-fishway.jpg|View of the hydropower plant and nature like fishway at Ellzee (source: Olav König).
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river (source: Nicole Kalinowski, IBF Umwelt).
</gallery>

=Relevant Literature=

Altheim test case

2020-09-29T12:54:03Z

LB: /* Results */

File:Overview Altusried (c)OLAV KÖNIG.jpg

2020-09-29T12:34:08Z

LB: Areal view of the HPP Altusried with fish pass (source: Olav König)

== Summary ==
Areal view of the HPP Altusried with fish pass (source: Olav König)

Altusried test case

2020-09-29T12:25:14Z

LB: /* Hydrodynamic modelling */

[[Category:Test cases]]
{{Fact box for Altusried}}
{{Relevant SMTDs for Altusried}}

=Introduction=
The river Iller is located in the far south-western part of Germany. It flows into the river Danube near the city Ulm. The river Iller originates from the confluence of the three rivers Stillach, Breitach and Trettach near the city Oberstdorf in the “Allgäuer Alps”, south Germany.

It’s catchment area has a size of 2152 km2. The HPP Altusried is the first HPP of a power plant chain of five HPPs that are operated by the LEW Wasserkraft GmbH. The last HPP of the LEW Wasserkraft GmbH is near Lautrach. In the downstream area of the LEW Wasserkraft GmbH HPP chain there are an additional 8 HPPs.

The hydrology of the Iller is characterized by sustained flows in winter, high water levels in spring due to snow melting and low water periods from August to October. At Altusried, the main Test Case HPP at the Iller, the mean interannual discharge is 46.6 m3/s (level Kempten).

=About the hydropower plants=
The HPP at Altusried is a run-of-river HPP with an installed capacity of 4 MW and a mean annual output of 30 million kWh. The HPP has two Kaplan turbines, each with a flow rate of 50 m3/s and a drop height of 9 m. The hydropeaking operation mode has been minimized since 2014.

===Layout===
There is a big reservoir in the upstream area of the Hydropower plant. In the downstream area of the HPP the river Iller is still flowing. After a free flowing area of around 1500m impoundment by the next reservoir starts. The LEW Wasserkraft GmbH has built a fish bypass channel around the HPP in 2015. It is 700 m long and has a mean flow of 1 m3/s.

===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft GmbH is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [[https://wasserkraft.lew.de/lew-wasserkraft Read more.]]

===Pressures on the water body's ecosystem===
The main pressures on the water body are morphology and hydrology. The formerly high pressure for river continuity, has been reduced through a fish bypass channel which has been built in 2014 - 2015.

The pressures are mainly caused by morphological issues which are results of the HPP. There is a lack of important habitats such as juvenile habitats, spawning habitats and the reophilic interstitial. The LEW Wasserkraft GmbH is working on this challenges with two restauration programmes, the Illerstrategie 2020 and the EU-found program ISOBEL.

=Test case topics=
===Fish population===
The river is dominated by reophilic and potamodroumous species. The main species are greyling, barbel, nase, brown trout, danube salmon, chub and several small fish species. In the reservoir basins, typical lake fish species such as tench, rudd, carp and pike can also be found. Since 2016 the LEW together with the University of Augsburg are investigating what types and numbers of fish using the fish passes constructed by LEW on the 5 hydropower plants of (from downstream to upstream) Lautrach, Maria Steinbach, Legau, Fluhmühle and Altusried. Every fish swimming through a fish pass is caught in a catch construction upstream in the fish pass. The catch construction (called counting pool) is evaluated nearly daily and fish that are caught are measured (length) and marked. The mark is a blue dot on their belly near the left or right pectoral, pelvic or caudal fin, depending on the fish ladder they were passing. In this way, migratory route of marked fish can be evaluated.

===Migration devices===
A fish bypass channel has been built 2014 - 2015. It has a length of 700 m and a flow of 1 m3/s. To also fulfill a compensation habitat function, juvenile and spawning habitats have been built into the fish-bypass channel.

===Downstream migration===
Downstream migration is possible during weir overflow or while the bottom outlets are opened. Thrash racks in front of the turbines, with a spacing of 20 mm between the racks, prevent fish from swimming into the turbines.

===Upstream migration===
The upstream migration is possible through the fish bypass channel. Within a monitoring programm, over 7000 fish have been documented using the fish bypass channel for upstream migration within 3 years.

===E-flow===
The minimum outflow of the turbines is 9.0 m3/s, during the whole year. This regulation is part of the “Illerstrategie 2020” of the LEW Wasserkraft GmbH. It is based on the natural minimum flow of the river Iller.

=Research objectives and tasks=
At the Test Case Altusried, the ways fish are finding the downstream entry of fish bypass channels is being studies. For this, fish tagging and [[acoustic telemetry]] is used to follow the ways of fish into the bypass channel. Additionally, Flow measurements are conducted in the outflow area of the fish ladder. This information is used to develop an agent-based fish movement model incorporated in the fish habitat simulation model [[CASiMiR]]. The research work is implemented by LEW, SJE, INBO, and TUT.

===Research tasks===
The research tasks and field studies conducted at the HPP on the river Iller are:

* Telemetry studies
* Velocity fluctuation measurements using the Lateral Line Probe
* 2D hydrodynamic model and CASiMiR migration model
* Population and habitat analysis

=Results=
===Population and habitat analysis===
The impact of the newly created fish-bypass channels and habitat measures have been monitored with electro fishing campaigns from 2016 – 2019 that are carried out twice a year on a length of 1500m downstream at both shorelines against the flow and in the middle of the river with the flow. The results of the electro fishing campaigns indicate the presence of all characteristic fish species in the Iller and thus an improvement of the formerly poor fish community status. Especially barbel, Danube salmon, grayling, chub and brown trout were caught in gratifying numbers, both in juvenile and adult stages. In spring 2018 even 6 young Danube Salmon were found. Only the population of nase is still in a rather poor condition.

===Acoustic 2D telemetry fish tracking===
The Vemco Positioning System (VPS) was applied to track fish swimming behaviour in 2D. Through the fish telemetry study, 15 million fish positions of 47 wild fish, 25 grayling and 22 barbel were collected. The tagged fish stayed in the VPS network between 2 and 92 days, whereby barbel resided on average for longer in the area than grayling. A detailed analysis is under way. The fish detections of the hydrophones in the fish pass already indicate that 12 tagged grayling and 8 tagged barbel found the entrance of the fish ladder at least once and swum up at least half way. Of these, 10 grayling and 6 barbel then also found their way upstream into the counting pool.

===Hydrodynamic modelling===
A hydrodynamic model was set up using Hydro-As_2D to derive flow velocities and water depth as input parameter for the developed migration model. To cover the wide flow range that can occur during migration periods, the flow scenarios considered in the model range from 10 m3/s to 80 m3/s. The results from the hydrodynamic model show that for a low flow situation with 10 m3/s the flow velocities are increased close to the area of the fish ladder outlet. Usually this zone of increased flow velocities is considered to have a guiding function for fish searching the fish ladder entrance. But even for the low flow situation the increased flow velocities can only be detected in the direct vicinity of the fish ladder entrance. For higher flows the extension of the higher flow velocity area is much less distinct.

===Migration model===
An extension of the habitat simulation system CASiMiR is being developed with input from the Test Cases. This new CASiMiR-Migration model is designed to simulate the migration behaviour of fish. For Altusried, the model has been applied to a lower flow velocity threshold of 0.15 m/s and an upper threshold of 1.5 m/s. When positioning the virtual fish equally over the river width in the lower part of the river stretch 10% of fish find the fish ladder entrance with flow velocities of 10 m3/s, 7% with 20 m3/s and 5 % with 60 m3/s in the river. I.e. the higher the flow in river the less distinct is the attraction flow when considering only flow magnitude and direction. By a first evaluation of the fish tracks it is already clear that the percentage of fish finding the fish ladder entrance is much higher than these values. This indicates that the current model has to consider additional parameters as mentioned before.

=Gallery=

=Relevant Literature=

Template:Fact box for Freudenau

2020-04-29T15:37:07Z

LB:

{| class="wikitable" style="float:right;width:350px;"
! colspan="2" style="text-align: center;background-color:#2cb4da; color:#ffffff;" | Fact box: Freudenau
|-
| Country
| Austria
|-
| River
| Danube
|-
| Operator
| VERBUND
|-
| Capacity
| 172 MW
|-
| Head
| 8.6 m
|-
| Inter-annual discharge
| 3000 m3/s
|-
| Turbine(s)
| 6 Kaplan bulb turbines
|-
| Detailed report
|[[:file:testcase_presentation_Freudenau.pdf|Click for pdf]]
|}

Freudenau test case

2020-04-29T15:35:57Z

LB: /* Introduction */

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second largest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km². The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m³/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. The group generates around 95 % of its electricity from renewable energy, primarily from hydropower. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream is fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 8-10 cm per year. The amount of added gravel is about 235.000 m³ per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=
A feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. The telemetry study will be limited to the fish pass and an area of 500 – 800m downstream of its entrance. In spring 2020 nase will be tagged for the actual telemetry study.

In order to analyse potential cues for orientation, a numerical model of the fish pass and downstream area of the HPP has been set up using Flow 3D. The model couples hydro-thermo-chemical cues and will be combined with the fish swimming path to be obtained from the telemetry study.

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau hydropower plant (source:Verbund).
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine at hydropower plant Freudenau (source: Verbund).
fredenau_fishway.jpg|Nature-like fishway at Freudenau (source: Verbund).
Layout-2-Freudenau_Verbund.png|Layout of the hydropower plant Freudenau (source: Verbund).
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of the hydropower plant Freudenau (source: Verbund).
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP and its different sections (source: Verbund).
fredenau_adding_sediments.jpg|Sediment is being added downstream of the hydropower plant Freudenau (source: Verbund).
</gallery>

=Relevant Literature=

Freudenau test case

2020-04-29T15:34:59Z

LB: /* Introduction */

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second largest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km². The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m3/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. The group generates around 95 % of its electricity from renewable energy, primarily from hydropower. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream is fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 8-10 cm per year. The amount of added gravel is about 235.000 m³ per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=
A feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. The telemetry study will be limited to the fish pass and an area of 500 – 800m downstream of its entrance. In spring 2020 nase will be tagged for the actual telemetry study.

In order to analyse potential cues for orientation, a numerical model of the fish pass and downstream area of the HPP has been set up using Flow 3D. The model couples hydro-thermo-chemical cues and will be combined with the fish swimming path to be obtained from the telemetry study.

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau hydropower plant (source:Verbund).
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine at hydropower plant Freudenau (source: Verbund).
fredenau_fishway.jpg|Nature-like fishway at Freudenau (source: Verbund).
Layout-2-Freudenau_Verbund.png|Layout of the hydropower plant Freudenau (source: Verbund).
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of the hydropower plant Freudenau (source: Verbund).
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP and its different sections (source: Verbund).
fredenau_adding_sediments.jpg|Sediment is being added downstream of the hydropower plant Freudenau (source: Verbund).
</gallery>

=Relevant Literature=

File:Gunz oberegg hpp.jpg

2020-04-29T15:32:26Z

LB:

{{Information
|author=Olav König
|source=https://www.fithydro.eu/guenz/
|description=The diversion weir at Deisenhausen, upstream of the hydropower plant Oberegg .
}}

Günz test case

2020-04-29T15:31:59Z

LB:

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 60 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by flood peaks in winter due to snow melting and some flood peaks in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 450 kW at(Höselhurst and Wattenweiler, 600 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.8 – 3.7 millions kWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW Wasserkraft is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [https://wasserkraft.lew.de/lew-wasserkraft]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The LEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical simulations of flow and habitat conditions in the fishway

=Results=

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg| The hydropower plant Ellzee on the river Günz (source: LEW).
Gunz_hosenhurst_hpp.jpg|The hydropower plant Hösellhurst with fish pass on the river Günz (source: Olav König).
Gunz_oberegg_hpp.jpg|The diversion weir at Deisenhausen, upstream of the hydropower plant Oberegg (source: LEW).
Günz-layout.png|Location of the 5 test case hydropower plants on the Günz river (source: LEW).
HPP-Ellzee-nature-like-fishway.jpg|View of the hydropower plant and nature like fishway at Ellzee (source: Olav König).
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river (source: Nicole Kalinowski, IBF Umwelt).
</gallery>

=Relevant Literature=

Template:Fact box for Günz

2020-04-29T15:30:33Z

LB:

{| class="wikitable" style="float:right;width:350px;"
! colspan="2" style="text-align: center;background-color:#2cb4da; color:#ffffff;" | Fact box: Günz
|-
| Country
| Germany
|-
| River
| Günz
|-
| Operator
| LEW
|-
| Capacity
| 350 - 1100 kW
|-
| Head
| 5 m
|-
| Inter-annual discharge
| 7.8 m3/s
|-
| Turbine(s)
| 1 Kaplan turbine at every HPP
|-
| Detailed report
|[[:file:testcase_presentation_Günz.pdf|Click for pdf]]
|}

File:Altheim underwater.jpg

2020-04-24T09:19:05Z

LB:

{{Information
|author=Uniper
|source=Uniper
|description=Underwater picture of fish at one of the structures.
}}

File:Altheim structure 2.jpg

2020-04-24T09:18:14Z

LB:

{{Information
|author=Uniper
|source=Uniper
|description=Relocation of gravel als spawning habitat
}}

Altheim test case

2020-04-24T09:17:28Z

LB: /* Gallery */

[[Category:Test cases]]
{{Fact box for Altheim}}
{{Relevant SMTDs for Altheim}}
=Introduction=
The river Isar, located in the south of Germany, is an Alpine river. It flows from its source in Austria at 1600 m above sea level through the Alps, pre-alpine moorlands and through the city of Munich before entering the Danube river near Deggendorf at 300 m above sea level. With a length of 260 km it is the fourth largest river in Bavaria and the second most important tributary of the Danube in Germany.

The catchment area of the Isar covers 8960 km2 in the Alps and the Karwendel mountains. The Isar is generally divided into three sections: the Upper Isar, the Middle Isar and the Lower Isar. The Test Case hydropower plant Altheim is located in the Lower Isar, at km 67.2, near the town Altheim. Downstream of the Test Case, 7 additional hydropower plants are located along the Isar.
The section of the Isar that relates to the Test Case Altheim has a catchment area of 88.2 km2 and is about 73 km long. It has an intern-annual discharge of 163 m3/s. Typically the discharge characteristics show high flows and fast floods in spring time during snow melt and rather low flows in winter. It is classified as a waterbody with poor ecological status.

=About the hydropower plant=
The hydropower plant at Altheim, commissioned in 1951, is a block-type hydropower plant and part of a chain of power plants in the Isar. The catchment area of this river stretch is about 7.908 km². It has an installed capacity of 17.8 MW and a mean annual output of 91.4 GWh. The plant has a gated weir with 4 bays located on the right of the power house and a head storage volume of 1,980,000 m3.

The normal operating level is at 384.00 m above sea level, in swelling operation it can be lowered by 1.00 m. On average, there are 2 peaks per day, where the flow changes roughly between 50 m3/s and 170 m3/s with ramps of about 100 m3/s per hour or a change of water level between +45 cm/h to - 30 cm/h.
===Layout===
The area around the power plant is dominated by commercial and living areas on the left side and a popular local recreation area with lakes for swimming on the right side, as well as a sewage treatment plant in Altheim.
===The Operator: Uniper SE===
Uniper Hydro Germany operates 109 hydroelectric power plants, containing run of river plants, storage and pumped storage. Alongside the rivers Lech, Isar, Danube and Main more than 1300 kilometres are used for the production of clean electricity. In close cooperation with regional stakeholders (politicians, authorities, NGOs) Uniper takes over responsibility to protect civil areas from floods, but also to protect the environment. [https://www.uniper.energy/ Read more.]

=Pressures on the water body's ecosystem=
The main pressures on the water body are nutrients, river specific pollutants, agricultural production and hydromorphological changes. These are on the one hand related to agriculture on the other hand the hydromorphology is impacted by the sequence of hydropower plants and their related ponds. Moreover, the chemical pressure (especially mercury) cannot be neglected.

=Test case topics=
===Fish population===
The relevant water body is located in the barbel region (epipotamal) and is therefore dominated by potamodromous species. During electro fishing in autumn 2007, 43 fish species could be identified, containing 35 indigenious species, 27 red listed species and 9 FFH species, which were mainly rheophile fish. Out of those, six were endemic species: Hucho hucho, Rutilus pigus, Gobio albipinnatus, Gymnocephalus schraetser, Zingel zingel and Zingel streber.
===Upstream migration===
The dimensioning criteria for the upstream migration facility, which was built in 2015, were the fish species Barbus barbus and Hucho hucho. The fish pass consists of a rough channel for the downstream connection at the entry of the fish pass. It is located on the right-hand side 300 m downstream of the power plant. An existing ditch has been used to facilitate the fish passage over 4.5 km and for providing new hydromorphological structures and habitats in the fish pass. Upstream, a vertical slot connects the nature-like fish pass to the river. This migration facility is always supplied with a minimum flow of 450 l/s which can be extended to up to 800 l/s.
===E-flow===
HPP Altheim is one HPP in a chain of hydropower plants. Usually a minimum flow of 40 m3/s is operated, a full stop of machines is a rare exception. For own purposes, one machine for station supply must always be operated with a minimum of 11.7 m3/s. Although the connected small stream Längenmühlbach has an agreed minimum e-flow of 3.2 m3/s all year, it is not within the scope of the Altheim Test Case within FIThydro.

=Research objectives and tasks=
Within the project, the fish pass at the plant shall be evaluated regarding the effectiveness of its existing hydromorphological structures. Both, the variation of the original structures to the current status as well as the usage of the existing habitats by fish shall be evaluated. Based on the results a concept for improved hydromorphological measures shall be developed under the consideration of acceptance by fish and expenses for maintenance. Moreover, the experiences with the maintenance of the nature-like fish passes shall be evaluated. This will be relevant for further decisions on the implementation of upstream migration measures.
===Research tasks===
The research tasks and field studies conducted at the Altheim HPP are:

* Mapping the availability of habitat structures and analysing their added value for migrating fish
* Evaluating the maintenance costs of a nature-like fish pass
=Results=
Over a total length of 1.5 km of the natural fish pass one habitat structure every 100 m has been implemented. The structures mainly consist of dead wood and spawning gravel and were constructed as spawning habitats, juvenile habitats or shelter but also to generally increase the variability in flow conditions. 5 structures are being observed with underwater photography in comparison to similar locations within in the fish pass without structural improvements to compare the effects and benefits. The first impressions indicate that the new habitat structures show a much higher density of the relevant fish species.

=Gallery=
<gallery mode=packed>
altheim_overview.jpg|Aerial view of Altheim dam, power plant, and reservoir (source: Uniper).
altheim_natural_fishway.jpg|Entrance to the nature-like fishway at Altheim (source: Uniper).
altheim_layout.png|Layout of the Altheim powerplant and the surrounding area (source: google maps, Uniper).
altheim_natural_fishway_downstream.jpg|View of the Altheim nature-like fishway from downstream (source: Uniper).
altheim_migration_layout.jpg|Layout of the fish migration system at the hydropower plant Altheim (source: google maps, Uniper).
Altheim structure 1.jpg|thumb|Implementation of rocks to vary flow conditions (source: Uniper.
Altheim structure 2.jpg|thumb|Relocation of gravel as spawning habitat (source: Uniper).
Altheim underwater.jpg|thumb|Underwater picture of fish at one of the structures (source: Uniper).
</gallery>

=Relevant Literature=

File:Altheim structure 1.jpg

2020-04-24T09:14:47Z

LB:

{{Information
|author=Uniper
|source=Uniper
|description=Placement of rocks to vary flow conditions.
}}

File:Altheim natural fishway.jpg

2020-04-24T09:13:00Z

LB:

{{Information
|author=Uniper
|source=https://www.fithydro.eu/altheim/
|description=Outlet of the Altheim nature-like fishway.
}}

Freudenau test case

2020-04-22T08:57:56Z

LB:

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second longest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km2. The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m3/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. More than four fifths of its electricity is produced by hydropower, supplemented by thermal and wind power. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream will be fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 2-3.5 cm per year. The amount of added gravel is about 190.000 m3 per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=
A feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. The telemetry study will be limited to the fish pass and an area of 500 – 800m downstream of its entrance. In spring 2020 nase will be tagged for the actual telemetry study.

In order to analyse potential cues for orientation, a numerical model of the fish pass and downstream area of the HPP has been set up using Flow 3D. The model couples hydro-thermo-chemical cues and will be combined with the fish swimming path to be obtained from the telemetry study.

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau hydropower plant (source:Verbund).
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine at hydropower plant Freudenau (source: Verbund).
fredenau_fishway.jpg|Nature-like fishway at Freudenau (source: Verbund).
Layout-2-Freudenau_Verbund.png|Layout of the hydropower plant Freudenau (source: Verbund).
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of the hydropower plant Freudenau (source: Verbund).
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP and its different sections (source: Verbund).
fredenau_adding_sediments.jpg|Sediment is being added downstream of the hydropower plant Freudenau (source: Verbund).
</gallery>

=Relevant Literature=

Altheim test case

2020-04-22T08:47:23Z

LB:

[[Category:Test cases]]
{{Fact box for Altheim}}
{{Relevant SMTDs for Altheim}}
=Introduction=
The river Isar, located in the south of Germany, is an Alpine river. It flows from its source in Austria at 1600 m above sea level through the Alps, pre-alpine moorlands and through the city of Munich before entering the Danube river near Deggendorf at 300 m above sea level. With a length of 260 km it is the fourth largest river in Bavaria and the second most important tributary of the Danube in Germany.

The catchment area of the Isar covers 8960 km2 in the Alps and the Karwendel mountains. The Isar is generally divided into three sections: the Upper Isar, the Middle Isar and the Lower Isar. The Test Case hydropower plant Altheim is located in the Lower Isar, at km 67.2, near the town Altheim. Downstream of the Test Case, 7 additional hydropower plants are located along the Isar.
The section of the Isar that relates to the Test Case Altheim has a catchment area of 88.2 km2 and is about 73 km long. It has an intern-annual discharge of 163 m3/s. It is classified as a waterbody with poor ecological status.

=About the hydropower plant=
The hydropower plant at Altheim, commissioned in 1951, is a block-type hydropower plant and part of a chain of power plants in the Isar. It has an installed capacity of 17.8 MW and a mean annual output of 91.4 GWh. The plant has a gated weir with 4 bays located on the right of the power house and a head storage volume of 1,980,000 m3.

The normal operating level is at 384.00 m above sea level, in swelling operation it can be lowered by 1.00 m. On average, there are 2 peaks per day, where the flow changes roughly between 50 m3/s and 170 m3/s with ramps of about 100 m3/s per hour or a change of water level between +45 cm/h to - 30 cm/h.
===Layout===
The area around the power plant is dominated by commercial and living areas on the left side and a popular local recreation area with lakes for swimming on the right side, as well as a sewage treatment plant in Altheim.
===The Operator: Uniper SE===
Uniper Hydro Germany operates 109 hydroelectric power plants, containing run of river plants, storage and pumped storage. Alongside the rivers Lech, Isar, Danube and Main more than 1300 kilometres are used for the production of clean electricity. In close cooperation with regional stakeholders (politicians, authorities, NGOs) Uniper takes over responsibility to protect civil areas from floods, but also to protect the environment. [https://www.uniper.energy/ Read more.]

=Pressures on the water body's ecosystem=
The main pressures on the water body are nutrients, river specific pollutants, agricultural production and hydromorphological changes. These are on the one hand related to agriculture on the other hand the hydromorphology is impacted by the sequence of hydropower plants and their related ponds. Moreover, the chemical pressure (especially mercury) cannot be neglected.

=Test case topics=
===Fish population===
The relevant water body is located in the barbel region (epipotamal) and is therefore dominated by potamodromous species. During electro fishing in autumn 2007, 43 fish species could be identified, containing 35 indigenious species, 27 red listed species and 9 FFH species, which were mainly rheophile fish. Out of those, six were endemic species: Hucho hucho, Rutilus pigus, Gobio albipinnatus, Gymnocephalus schraetser, Zingel zingel and Zingel streber.
===Upstream migration===
The dimensioning criteria for the upstream migration facility, which was built in 2015, were the fish species Barbus barbus and Hucho hucho. The fish pass consists of a rough channel for the downstream connection at the entry of the fish pass. It is located on the right-hand side 300 m downstream of the power plant. An existing ditch has been used to facilitate the fish passage over 4.5 km and for providing new hydromorphological structures and habitats in the fish pass. Upstream, a vertical slot connects the nature-like fish pass to the river. This migration facility is always supplied with a minimum flow of 450 l/s which can be extended to up to 800 l/s.
===E-flow===
HPP Altheim is one HPP in a chain of hydropower plants. Usually a minimum flow of 40 m3/s is operated, a full stop of machines is a rare exception. For own purposes, one machine for station supply must always be operated with a minimum of 11.7 m3/s. Although the connected small stream Längenmühlbach has an agreed minimum e-flow of 3.2 m3/s all year, it is not within the scope of the Altheim Test Case within FIThydro.

=Research objectives and tasks=
Within the project, the fish pass at the plant shall be evaluated regarding the effectiveness of its existing hydromorphological structures. Both, the variation of the original structures to the current status as well as the usage of the existing habitats by fish shall be evaluated. Based on the results a concept for improved hydromorphological measures shall be developed under the consideration of acceptance by fish and expenses for maintenance. Moreover, the experiences with the maintenance of the nature-like fish passes shall be evaluated. This will be relevant for further decisions on the implementation of upstream migration measures.
===Research tasks===
The research tasks and field studies conducted at the Altheim HPP are:

* Mapping the availability of habitat structures and analysing their added value for migrating fish
* Evaluating the maintenance costs of a nature-like fish pass
=Results=
Over a total length of 1.5 km of the natural fish pass one habitat structure every 100 m has been implemented. The structures mainly consist of dead wood and spawning gravel and were constructed as spawning habitats, juvenile habitats or shelter but also to generally increase the variability in flow conditions. 5 structures are being observed with underwater photography in comparison to similar locations within in the fish pass without structural improvements to compare the effects and benefits. The first impressions indicate that the new habitat structures show a much higher density of the relevant fish species.

=Gallery=
<gallery mode=packed>
altheim_overview.jpg|Aerial view of Altheim dam, power plant, and reservoir (source: Uniper).
altheim_natural_fishway.jpg|Entrance to the nature-like fishway at Altheim (source: Uniper).
altheim_layout.png|Layout of the Altheim powerplant and the surrounding area (source: google maps, Uniper).
altheim_natural_fishway_downstream.jpg|View of the Altheim nature-like fishway from downstream (source: Uniper).
altheim_migration_layout.jpg|Layout of the fish migration system at the hydropower plant Altheim (source: google maps, Uniper).
</gallery>

=Relevant Literature=

Günz test case

2020-04-22T08:43:42Z

LB:

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 55 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by peak flows in winter due to snow melting and some peak flows in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 450 kW at(Höselhurst and Wattenweiler, 600 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.8 – 3.7 millions kWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: Bayerische Elektrizitätswerke GmbH (BEW)===
The BEW is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operator in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [http://www.bew-augsburg.de/ Read more.]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The BEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical Simulation
=Results=

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg| The hydropower plant Ellzee on the river Günz (source: LEW).
Gunz_hosenhurst_hpp.jpg|The hydropower plant Hösellhurst with fish pass on the river Günz (source: Olav König).
Gunz_oberegg_hpp.jpg|The hydropower plant Oberegg on the river Günz (source: LEW).
Günz-layout.png|Location of the 5 test case hydropower plants on the Günz river (source: LEW).
HPP-Ellzee-nature-like-fishway.jpg|View of the hydropower plant and nature like fishway at Ellzee (source: Olav König).
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river (source: Nicole Kalinowski, IBF Umwelt).
</gallery>

=Relevant Literature=

Günz test case

2020-04-22T08:33:50Z

LB:

[[Category:Test cases]]
{{Fact box for Günz}}
{{Relevant SMTDs for Günz}}

=Introduction=
The river Günz is located in the southern part of Bavaria, Germany. It is about 55 km long and flows into the river Danube near the city Günzburg. The catchment area of the river Günz is 710 km2. The Günz is fed by the confluence of the “Eastern Günz” and the “Western Günz” near the small city Lauben. The Test Case consists of a row of 5 hydropower plants, which are located on the Günz.

The hydrology of the Günz is characterized by peak flows in winter due to snow melting and some peak flows in the summer after heavy rain events. The catchment area of the river Günz is 710 km2 The mean interannual discharge of the river Günz is estimated at 7.8 m3/s. The river is classified with a moderate ecological status.

=About the hydropower plants=
The Test Case Günz comprises 5 consecutive hydropower plants. Four of them are run-of-river hydropower plants and one, the HPP Oberegg, has a diverted reach.
Each of the 5 HPPs is equipped with one Kaplan-turbine, with installed capacities of 350 kW at Waldstetten, 450 kW at(Höselhurst and Wattenweiler, 600 kW at Ellzee and 1100 kW at Oberegg. The annual output is between 1.8 – 3.7 millions kWh . The height drop ranges from 3.9 to 8.3 m at the different HPPs.
===Layout===
The HPPs Höselhurst, Wattenweiler, Ellzee and Waldstetten are run-of-river HPPs, the HPP Oberegg is a diversion hydropower plant (Ausleitungskraftwerk). In the upstream areas of the HPPs there are reservoirs. In the downstream areas the river Günz is still free flowing until the head of the next reservoir. There is a fish bypass channel at every HPP. At the run-of river HPPs they are built as a classical conventional pond system. At Oberegg the fish passage facility for upstream fish migration is integrated into the diverted reach, which is called “Alte Günz”.
===The Operator: Bayerische Elektrizitätswerke GmbH (BEW)===
The BEW is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operator in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [http://www.bew-augsburg.de/ Read more.]

=Pressures on the water body's ecosystem=
The main pressures on the water body are hydrology, agricultural use of pesticides, effluents from a nearby water treatment plant, and to some extent the spill over from storm water overflow. Previously, continuity was classified as a high pressure, but this was counteracted through the building of fishways in 2014. The pressures are mainly caused of morphological issues which are results of the HPP. There is a lack of important habitats like juvenile habitats, spawning habitats and the reophilic interstitial. The BEW is working on this problems with a restauration program.

=Test case topics=
===Fish population===
The river is dominated by reophilic fish species. The main species are white fish species like nase (Chondrostoma nasus), barbel (Barbus barbus), roach (Rutilus rutilus) and chub (Squalius cevalus). Furthermore, there are many small fish species like bleak (Alburnus alburnus), Bitterling (Rhodeus amarus) and gudgeon (Gobio gobio). Due to the anthropogenic river changes there are also many stagnopil species like pike (Esox lucius) and tench (Tinca tinca).
===Upstream migration===
There is a fish bypass channel for upstream migration at every HPP. The bypass channel at HPP Deisenhausen has a flow of 500 l/s and is 500 m long. All other fish bypass channels have a flow of 300 l/s and a length of 130 – 180 m. All fish bypass channels are built as a nature like pond system. The first 10 m of every fish bypass channel is built as a technical vertical slot pass to ensure a more or less consistent water flow. In every fish bypass channel there is furthermore a fish counting pool to register all (upward) migrating fish. This research study is done by Thomas Lechner (IBF Umwelt).
===E-flow===
The Test Case HPPs at the Günz are run-of river and diversion HPPs. The mean flow runs over the basin Oberegg, there is no hydropeaking. The old river called “Alte Günz” is used as a flood channel. The e-flow is 500 l/s at all time, which is the natural minimum water flow. This is the e-flow the authorities specified.

=Research objectives and tasks=
This section of the Günz is strongly morphologic downgraded and channelized. The morphologic improvement of the Günz itself is difficult because of the closeness to the settlements and no available areas. Therefore, compensation habitats especially as spawning habitats and habitat for reophile fish species are being investigated to upgrade the ecology of strongly channelized rivers. Based on the findings, compensation habitats in the fish passes will be build.
===Research tasks===
The research tasks and field studies conducted at the HPPs on the river Günz are:

* Potential scenario modelling
* Potential test of CIA tools
* Management, monitoring and construction of spawning habitats in fishway
* Numerical Simulation
=Results=

=Gallery=
<gallery mode=packed>
Gunz_elizee_HPP.jpg|Ellzee HPP.
Gunz_hosenhurst_hpp.jpg|Hösenhurst HPP.
Gunz_oberegg_hpp.jpg|Oberegg HPP.
Günz-layout.png|Location of the test case HPPs on the Günz river.
HPP-Ellzee-nature-like-fishway.jpg|Nature like fishway at Ellzee HPP.
gunz-nature-like-fishway.jpg|Close-up of a nature-like fishway in the Günz river.
</gallery>

=Relevant Literature=

Altusried test case

2020-04-22T08:32:58Z

LB:

[[Category:Test cases]]
{{Fact box for Altusried}}
{{Relevant SMTDs for Altusried}}

=Introduction=
The river Iller is located in the far south-western part of Germany. It flows into the river Danube near the city Ulm. The river Iller originates from the confluence of the three rivers Stillach, Breitach and Trettach near the city Oberstdorf in the “Allgäuer Alps”, south Germany.

It’s catchment area has a size of 2152 km2. The HPP Altusried is the first HPP after the source of the river Iller. The last HPP of the BEW is near Memmingen. In the downstream area of the BEW HPP chain there are an additional 8 HPPs.

The hydrology of the Iller is characterized by sustained flows in winter, high water levels in spring due to snow melting and low water periods from August to October. At Altusried, the main Test Case HPP at the Iller, the mean interannual discharge is estimated to be 46.6 m3/s.

=About the hydropower plants=
The HPP at Altusried is a run-of-river HPP with an installed capacity of 4 MW and a mean annual output of 30 million kWh. The HPP has two Kaplan turbines, each with a flow rate of 50 m3/s and a drop height of 9 m. The hydropeaking operation mode has been minimized since 2014.

===Layout===
There is a big reservoir in the upstream area of the Hydropower plant. In the downstream area of the HPP the river Iller is still flowing. After a free flowing area of around 1500m impoundment by the next reservoir starts. The BEW has built a fish bypass channel around the HPP in 2015. It is 700 m long and has a mean flow of 1 m3/s.

===The Operator: LEW Wasserkraft GmbH (LEW)===
The LEW is a 100 % subsidiary of the Lechwerke AG. It runs and maintains 36 HPPs at the rivers Danube, Günz, Lech and Iller and is thereby one of the leading HPP operators in Bavaria, Germany. The company produces over 1 billion kWh energy out of regenerative hydropower per year. [[https://wasserkraft.lew.de/lew-wasserkraft Read more.]]

===Pressures on the water body's ecosystem===
The main pressures on the water body are effluents from a water treatment plant, hydrology, and, to a small extent, the spillover from storm water overflows and morphology. The formerly high pressure for river continuity, has been reduced through fish bypass channels which were built in 2014.

The pressures are mainly caused by morphological issues which are results of the HPP. There is a lack of important habitats such as juvenile habitats, spawning habitats and the reophilic interstitial. The BEW is working on this challenges with two restauration programmes, the Illerstrategie 2020 and the EU-found program ISOBEL.

=Test case topics=
===Fish population===
The river is dominated by reophilic and potamodroumous species. The main species are greyling, barbel, nase, brown trout, danube salmon, chub and several small fish species. In the reservoir basins, typical lake fish species such as tench, rudd, carp and pike can also be found. Since 2016 the LEW together with the University of Augsburg are investigating what types and numbers of fish using the fish passes constructed by LEW on the 5 hydropower plants of (from downstream to upstream) Lautrach, Maria Steinbach, Legau, Fluhmühle and Altusried. Every fish swimming through a fish pass is caught in a catch construction upstream in the fish pass. The catch construction (called counting pool) is evaluated nearly daily and fish that are caught are measured (length) and marked. The mark is a blue dot on their belly near the left or right pectoral, pelvic or caudal fin, depending on the fish ladder they were passing. In this way, migratory route of marked fish can be evaluated.

===Migration devices===
The Bragado weir does not have a fish pass for either upstream or downstream fish migration. Such device was considered unnecessary by the Portuguese authorities since the HPP is placed in a reach of the Avelames River with reduced natural longitudinal connectivity, due to the occurrence of natural falls. Furthermore, migratory fish species requiring long distance movements to reproduce do not occur in this river.

===Downstream migration===
Downstream migration is possible during weir overflow or while the bottom outlets are opened. Thrash racks in front of the turbines, with a spacing of 20 mm between the racks, prevent fish from swimming into the turbines.

===Upstream migration===
The upstream migration facility, which was built in 2014, consists of a fish bypass channel with a length of 700 m and a flow of 1 m3/s. To also fulfill a compensation habitat function, juvenile and spawning habitats have been built into the fish-bypass channel.

===E-flow===
The minimum outflow of the turbines is 9.0 m3/s, during the whole year. This regulation is part of the “Illerstrategie 2020” of the BEW. It is based on the natural minimum flow of the river Iller.

=Research objectives and tasks=
At the Test Case Altusried, the ways fish are finding the downstream entry of fish bypass channels is being studies. For this, fish tagging and [[acoustic telemetry]] is used to follow the ways of fish into the bypass channel. Additionally, Flow measurements are conducted in the outflow area of the fish ladder. This information is used to develop an agent-based fish movement model incorporated in the fish habitat simulation model [[CASiMiR]]. The research work is implemented by LEW, SJE, INBO, and TUT.

===Research tasks===
The research tasks and field studies conducted at the HPP on the river Iller are:

* Telemetry studies
* Velocity fluctuation measurements using the Lateral Line Probe
* 2D hydrodynamic model and CASiMiR migration model
* Population and habitat analysis

=Results=
===Population and habitat analysis===
The impact of the newly created fish-bypass channels and habitat measures have been monitored with electro fishing campaigns from 2016 – 2019 that are carried out twice a year on a length of 1500m downstream at both shorelines against the flow and in the middle of the river with the flow. The results of the electro fishing campaigns indicate the presence of all characteristic fish species in the Iller and thus an improvement of the formerly poor fish community status. Especially barbell, Danube salmon, grayling, chub and brown trout were caught in gratifying numbers, both in juvenile and adult stages. In spring 2018 even 6 young Danube Salmon were found. Only the population of nase is still in a rather poor condition.

===Acoustic 2D telemetry fish tracking===
The Vemco Positioning System (VPS) was applied to track fish swimming behaviour in 2D. Through the fish telemetry study, 15 million fish positions of 47 wild fish, 25 grayling and 22 barbel were collected. The tagged fish stayed in the VPS network between 2 and 92 days, whereby barbel resided on average for longer in the area than grayling. A detailed analysis is under way. The fish detections of the hydrophones in the fish pass already indicate that 12 tagged grayling and 8 tagged barbel found the entrance of the fish ladder at least once and swum up at least half way. Of these, 10 grayling and 6 barbel then also found their way upstream into the counting pool.

===Hydrodynamic modelling===
A hydrodynamic model has been set up using Hydro-As_2D to derive flow velocities and water depth as input parameter for the developed migration model. To cover the wide flow range that can occur during migration periods, the flow scenarios considered in the model range from 10 m3/s to 80 m3/s. The results from the hydrodynamic model show that for a low flow situation with 10 m3/s the flow velocities are increased close to the area of the fish ladder outlet. Usually this zone of increased flow velocities is considered to have a guiding function for fish searching the fish ladder entrance. But even for the low flow situation the increased flow velocities can only be detected in the direct vicinity of the fish ladder entrance. For higher flows the extension of the higher flow velocity area is much less distinct.

===Migration model===
An extension of the habitat simulation system CASiMiR is being developed with input from the Test Cases. This new CASiMiR-Migration model is designed to simulate the migration behaviour of fish. For Altusried, the model has been applied to a lower flow velocity threshold of 0.15 m/s and an upper threshold of 1.5 m/s. When positioning the virtual fish equally over the river width in the lower part of the river stretch 10% of fish find the fish ladder entrance with flow velocities of 10 m3/s, 7% with 20 m3/s and 5 % with 60 m3/s in the river. I.e. the higher the flow in river the less distinct is the attraction flow when considering only flow magnitude and direction. By a first evaluation of the fish tracks it is already clear that the percentage of fish finding the fish ladder entrance is much higher than these values. This indicates that the current model has to consider additional parameters as mentioned before.

=Gallery=

=Relevant Literature=

Altheim test case

2020-04-22T08:30:50Z

LB:

Freudenau test case

2020-04-22T08:30:06Z

LB:

[[Category:Test cases]]
{{Fact box for Freudenau}}
{{Relevant SMTDs for Freudenau}}

=Introduction=
The Danube River is the second longest river in Europe with a total length of 2,850 km and a total catchment area of 817,000 km2. The project area is located on the upper reach of the Danube River (distance from the mouth: 1,921 km, catchment area: 100,700 km²) within the city of Vienna/Republic of Austria. The inter-annual discharge varies between 900 to 5000 m3/s.

The Danube water body upstream of the Test Case is classified as having a moderate to worse ecological potential, while the waterbody downstream is classified as a natural water body with good ecological status.

=About the hydropower plant=
The hydropower plant at Freudenau is a run-of river hydropower plant. It has an installed capacity of 172 MW and a mean annual output of 1,052 GWh.

===Layout===
The Hydropower Plant at Freudenau is a multi-purpose hydro-power scheme located in the southern region of the Vienna metropolitan area. Six Kaplan bulb turbines are installed in the power house which is located in the middle of the river between the lock and weir systems. With a runner diameter of 7.5 m the turbines rank among the biggest in Europe. Ecological measures include the water supply to the New and Old Danube, new biotopes, and an ecologically designed bypass stream as a fishway on the Danube island.

===The Operator: VERBUND===
VERBUND is Austria’s leading electricity company and one of the largest producers of electricity from hydropower in Europe. More than four fifths of its electricity is produced by hydropower, supplemented by thermal and wind power. VERBUND power plants cover 40% of the annual Austrian electricity requirement of approx. 70,000 million kWh. VERBUND was founded in 1947 and has been listed on the Vienna Stock Exchange since 1988; 51 % of the company’s shares are owned by the Republic of Austria.

In the area of the research & development of new applications for electricity, VERBUND is among the pioneers and innovation leaders and also rich in experience in successful implementation of LIFE Nature projects (e.g. LIFE+ Traisen, LIFE+ Netzwerk Donau).

=Pressures on the water body's ecosystem=
The Upstream water body (409040013) is a heavily modified water body with the following main pressures: hydropower, navigation and flood control.

All pressures are directly anthropogenic and highly connected to the need to save life and goods as well as economical use. The ecological potential based on the WFD is “moderate or worse”. The reasons for designation as HMWB ((heavily modified waterbody) are manifold and any measures to reach the good ecological status have significant adverse effects on hydropower, navigation, & flood control.

The Downstream water body (409040008) is a natural water body with the main pressures: navigation and flood control. The ecological status is defined as “good”.

=Test case topics=

===Fish population===
The river is dominated by potamodroumous species. Recent investigations (2010) of the fish fauna below the HPP (r-km 1880 - 1894) showed a good fish-ecological status according to WFD compliant assessment. A total of 31 species of the Leitbild and seven species not included in the Leitbild were found. The fish biomass was about 184 kg /ha and was dominated by pike, bream, pike prech, catfish, and Giebel. The abundance was about 7.500 Individuals per hectare and was dominated by bitterling, perch, roach, and rudd.

===Downstream migration===
Downstream migration is possible through the turbines (one of the largest turbines in Europe with a diameter of 7.5m), through the navigation locks, and through the nature-like fishway.

===Upstream migration===
During the course of construction of Freudenau power plant (commissioned in 1999), a fish pass was erected on the orographic left bank between the Danube and the flood discharge channel of the New Danube. This comprises an approx. 1 km long bypass stream and an upstream connecting pool pass. In the process, the bypass stream negotiates an average difference in height of 6.7 m and the pool pass that of 2 m. The entrance to the bypass stream is situated approx. 500 m downstream from the power plant‘s weir system. Two estuaries with a permanent flow of water ensure the attracting currents for detection of the fish passes. In the event of increased mean flows, a third branch forms as an additional residual flow.

Apart from the stable bank at the island between the Danube and the right estuary, as well as in the lowest section of the left estuary, the banks are unfortified. As a result, currents can lead to small-scale redistribution and continue to develop dynamically. In addition, parts of trees and rootstocks have been installed, which - as deadwood - represent important structures for fish habitats. The 19 pools of the pool passes comprise a total length of 420 m.

The average difference in water level between the individual pools amounts to 11 cm. The rough, asymmetric shape of the sills made from rough blocks increases the flow diversity and therewith the connectivity. The pools are characterized by flow rates of less than 1 m/s and scours of up to 1.5 m deep. As a result of the very slow flow velocity, fine sediment is increasingly covering the original sand-gravel mixture as integrated bottom substrate. The residual flow of the pool pass amounts to 900 l/s. The pool pass can receive additional residual water by means of an electronically controlled spillway gate or via an emergency pump. The bypass stream will be fed via the outflow from the pool stream and via two flood gates depending upon the season and water flowing from the Danube. The rewith with dynamic total residual flow fluctuates between 1,500 l/s and 3,600 l/s.

===Sediment management===
Gravel is artificially added downstream of the HPP (bed-load addition) to prevent further erosion. Without gravel feeding this erosion would be about 2-3.5 cm per year. The amount of added gravel is about 190.000 m3 per year to prevent this erosion.

=Research objectives and tasks=
The main interest for future planning of fishways in large rivers as the Danube is the positioning of the fishway entrance and the assumed “Sackgasseneffekt” (cul-de-sac-effect) during the upstream migration of fish. The Test Case Freudenau, situated on a large river, gives the opportunity to study this question. Orientation of potamodromous fish and implications for the positioning of the fishway entrance will be investigated using the method of numerical modelling of coupled hydro-thermo-chemical-mechanical cues. These results will be combined with the results and interpretations of fish swimming paths, obtained with 2D Telemetry. The field studies are subcontracted by VERBUND and the numerical computations are carried by TUM.

===Research tasks===
The research tasks and field studies conducted at Freudenau are:
*2D and 3D modelling of attraction flow at fishway
*Telemetry study of fish swimming paths
*Coupled hydro-thermo-chemical-mechanical modelling

=Results=
A feasibility study to test the possibilities of a successful telemetry study in such a large river as the Danube was carried out in 2019. While it is not possible to locate fish directly downstream of the turbines or to cover the whole width of the river due to heavy ship traffic, several hydrophone arrays were positively tested close to the influx building Langenzersdorf. Satisfying positioning results could be obtained using six hydrophones and test tags. The telemetry study will be limited to the fish pass and an area of 500 – 800m downstream of its entrance. In spring 2020 nase will be tagged for the actual telemetry study.

In order to analyse potential cues for orientation, a numerical model of the fish pass and downstream area of the HPP has been set up using Flow 3D. The model couples hydro-thermo-chemical cues and will be combined with the fish swimming path to be obtained from the telemetry study.

=Gallery=
<gallery mode=packed>
Areal-view-HPP-Freudenau_c_Verbund.jpg|Aerial view of Fredenau HPP.
Turbinen_cVerbund_web-scaled.jpg|Kaplan turbine in Freudenau HPP.
fredenau_fishway.jpg|Nature-like fishway at Freudenau HPP.
Layout-2-Freudenau_Verbund.png|Layout of Freudenau HPP.
Longitudinal-section-of-HPP-Freudenau_c_Verbund.png|Longitudinal section of Freudenau HPP.
Layout_3_Freudenau_cVerbund_web.jpg|Layout of the nature-like fishway at Freudenau HPP.
fredenau_adding_sediments.jpg|Sediment being added downstream of Freudenau HPP.
</gallery>

=Relevant Literature=