The flow-refuges, made of composite, were installed downstream Bragado and Covas do Barroso Small Hydropower Plants. During the Task 2 of the project, we tested different flow-refuges in the laboratory in order to select the best configuration, which means, the one that exhibited the highest use frequency and the lowest individual stress (measured by means of blood glucose on fish).
Trimarine compositos constructed the selected flow-refuge prototype (0.4 m x 0.5 m x 0.4 m) with composite materials (fiberglass and a matrix of polyester resin), which are known for their durability, resistance, and utility in aquatic environments.
Two flow-refuges prototypes were placed downstream of Bragado and Covas do Barroso SHP, with the entrance facing 45⁰ the flow direction downstream. This angle was the most successful regarding fish entrance in laboratory conditions.
Figure 1. Covas River downstream. Flow-refuge. Juan Fuentes-Perez (Smartfishways project) checking sensor data (from left to right).
Now, an underwater multispectral stereo camera is continuously monitoring the use of flow-refuges by fish with two imaging sensors (S16 dualflex) during the day (RGB color) and night (infrared, grayscale), a work done in straight collaboration with TalTech and IamHydro. The camera is equipped with a wiper to avoid biofilm growth in the camera glass, enabling accurate monitoring.
Additionally, in partnership with the project Smartfishways, a sensor network was installed close to the flow refuges that transmits in real-time and stores online environmental variables such as water level, luminosity, atmospheric pressure, and water and air temperature. These are related to fish biological responses and thus necessary to assess and discriminate fish behavior and refuge use under hydropeaking scenarios from other possible environmental cofactors.
Can you spot our flow-refuge in the river? J
The fish can!
Figure 2. Flow-refuge final set up at Covas River downstream Covas do Barroso Small Hydropower Plant.