Difference between revisions of "Anundsjö test case"

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The research tasks and field studies conducted at Anundsjö are:
 
The research tasks and field studies conducted at Anundsjö are:
  
* Bathymetry and velocity in reservoir
+
* Hydrodynamic conditions in reservoir and their impact on downstream smolt migration
* Bathymetry of the fishway and the entrance with GPS and drone flights for Structure for Motion (SfM)
+
* Physical conditions in the nature-like fishway and its functionality for upstream migration of salmon
* Bathymetry, flow velocity data and drone flights for SfM and habitat in bypassed river reach
+
* Access to the bypassed river reach for upstream migration
 +
* Use of advanced methods for mapping of bathymetry, measurements of water velocity and modelling
 +
 
 
=Results=
 
=Results=
  

Revision as of 13:38, 4 May 2020

Fact box: Anundsjö
Country Sweden
River Mo (Moälven)
Operator Statkraft
Capacity 5 MW
Head 61 m
Inter-annual discharge 10 m3/s
Turbine(s) 1 Francis turbine
Detailed report Click for pdf
Relevant solutions Applied in test case?
Bypass combined with other solutions Yes
Construction of a river-in-the-river -
Mitigating reduced annual flow and low flow measures Yes
Mitigating reduced flood peaks, magnitudes, and frequency -
Nature-like fishways Yes
Operational measures (turbine operations, spillway passage) Yes
Other types of fine screens -
Placement of spawning gravel in the river -
Placement of stones in the river -
Pool-type fishways Yes
Sensory, behavioural barriers (electricity, light, sound, air-water curtains) -
Skimming walls (fixed or floating) Yes
Vertical slot fishways -
Relevant MTDs Applied in test case?
3D fish tracking system Yes
3D sensorless, ultrasound fish tracking -
Acoustic Doppler current profiler (ADCP) Yes
Acoustic Doppler velocimetry (ADV) Yes
Acoustic telemetry Yes
Agent based model -
Barotrauma detection system -
CASiMiR -
COSH-tool -
Current meter Yes
Differential pressure sensor base artificial lateral line probe, iRon -
Double Averaging method Yes
Fish Protection System (induced drift application) -
FLOW-3D -
HEC-RAS -
Hydropeaking indicator -
Hydropeaking tool -
LiDAR -
OpenFOAM Yes
Particle image velocimetry (PIV) -
Radio frequency identification with passive integrated transponder (PIT tagging) -
Radio telemetry -
River2D -
Sediment simulation in intakes with Multiblock option (SSIIM) -
Shelter measurements -
Structure from motion (SfM) Yes
TELEMAC -

Introduction

The Test Case is located on the small river Mo (Moälven) in the northern part of Sweden. The hydrology of the river Mo is typical for north of Sweden, with a lot of snow in the winter, a spring flood when the snow melts, low flows during the summer and often some higher flows and an autumn flood before the next winter starts with snow accumulation.

The catchment area is 820 km2. Mean annual precipitation for the whole catchment area is approx. 727 mm per year, with a mean flow at the outlet into the Baltic Sea of 27.9 m3/s, and 10.2 m3/s at the HPP Anundsjø.

About the hydropower plant

The HPP is impounding a small reservoir, releasing the water through the turbines and a tunnel back into the river about 4km further downstream. It has an installed capacity of 5 MW. The mean annual discharge is 10 m3/s with a low flow of 2.21 m3/s.

Layout

A small reservoir of 0.5 ha is located upstream of the HPP Anundsjø. Further upstream are important areas of spawning for salmon and trout, which are not directly affected by the HPP. During the winter, a larger reservoir further upstream provides water to the HPP. The bypassed river reach between the dam and the outlet of the power plant is 4 km. This river reach receives an environmental flow release.

The Operator: Statkraft

Statkraft is a leading company in hydropower internationally and Europe’s largest generator of renewable energy. The Group produces hydropower, wind power, solar power, gas-fired power and supplies district heating. Statkraft is a global company in energy market operations. It is Norway's largest and the Nordic region's second largest power producer. Read more.

Pressures on the water body's ecosystem

Due to two dams downstream of the HPP, for which the fish passage efficiency is unknown, the continuity is moderate. Most parts of the rapids further downstream have been modified for timber floating, with only a few being restored. Furthermore, the hydrology directly downstream of the power plant outlet is affected by short-time regulation. The water level in the small reservoir may fluctuate by up to 0.5 m. A recurring problem in Sweden is pollution through Mercury, which is released from the ground through logging activities, causing a moderate pollution of the water body.

Test case topics

Fish population

The fish species that can be found in the Mo are: salmon, sea trout, grayling, pike, perch, brown trout and crayfish. During the summer from July to October, the power plant is shut down twice a week for one hour, releasing the discharge through the gates in order attract salmon into the residual area. However, after one hour this flow has still not reached downstream to the outlet of the power plant.

Downstream migration

To facilitate better downstream fish migration, a floating guidance device is attached right next to the intake, leading the fish into a smolt trap and then out to the downstream side of the dam. The license of 2012 states that this device shall be placed out 1 May every year and water released in the smolt trap shall be 0.25 m3/s. This solution was evaluated together with the authorities after the first year, 2016, and the conclusion was that it did not work as intended. In 2017 a new solution with fishing nets was tested, leading the smolts to the fishway instead. The water released to the smolt trap was then instead released to go through the fishway. The starting time for the installation fot he guidance device is moved to a flexible time due to when the reservoir is ice-free.

Upstream migration

The upstream migrating fish encounter the outlet of the power plant, located 4 km downstream the fishway. The attraction flow is represented by the minimum flow, 0.8 m3/s between the 15th of July and the 5th of October; 0.25 m3/s the rest of the year. At the end of the 4 km long residual area the upstream migration continues in the nature-like fishway. At the end of the nature-like fishway, there is a short concrete fish ladder for the final ascent into the reservoir.

E-flow

In the new license from 2012, the requirements are release of water in the fishway between the 15th of July and the 5th of October of 0.8 m3/s and the rest of the year 0.25 m3/s. During the same period one hour every Tuesday and Thursday, the power plant must shut down and release the full discharge through the gates in order to attract salmon up in the residual area.

Research objectives and tasks

The overall question at the HPP Anundsjø is how FIThydro can improve the situation for fish by different measures and means around the HPP. This includes the situation for the salmon smolt, which are mainly arriving at the HPP after being released in the upstream area. It also includes the situation of juvenile fish of different species as well as the possibility for salmon to pass on the way to spawn and back (influenced also by the HPP located downstream of Anundsjø and influencing especially the number of migrating fish).

Research tasks

The research tasks and field studies conducted at Anundsjö are:

  • Hydrodynamic conditions in reservoir and their impact on downstream smolt migration
  • Physical conditions in the nature-like fishway and its functionality for upstream migration of salmon
  • Access to the bypassed river reach for upstream migration
  • Use of advanced methods for mapping of bathymetry, measurements of water velocity and modelling

Results

Gallery