The meander‐type fish pass: An alternative to the conventional vertical slot pass: Fid-Bau Portal

The meander‐type fish pass: An alternative to the conventional vertical slot pass

Helbig, Ulf / Mende, Matthias / Dönni, Werner / Rathke, Klaas

The meander‐type fish pass is a slotted fishway characterised by the exclusive use of rounded and smooth components. Due to the specific geometry and arrangement of the basins, which differ considerably from the conventional vertical slot pass, there are significantly different hydraulic conditions. The water flow is guided along the basin walls by means of a dominant main current while the water body is much calmer towards the centre of the basin, where very low flow velocities are found. A detailed assessment of the functionality is currently impossible due to the small number of surveys of fish passage hitherto carried out. However, considerable potential is indicated by the high passage rates at some sites and the lack of selectivity with regard to species and small fish, together with the design advantages and the adaptation possibilities after construction work is completed. In this study, we offer some recommendations for dimensioning to enable this potential to be exploited. These are oriented around recommendations for conventional vertical slot passes regarding basin size, flow depth and slot width. Due to the great potential of the meander‐type fish pass, it is desirable to construct still more individual pilot passes to implement comprehensive surveys of fish passage on a sound methodological basis.