Modeling Water-Depth Distribution in Vertical-Slot Fishways under Uniform and Nonuniform Scenarios

Abstract

Vertical slot fishways are a type of fish pass of wide operating range that allow fish to move across obstacles in rivers. This study aims to model the performance of these structures, under uniform and nonuniform flow conditions, using discharge coefficients involving the downstream water level together with a logical algorithm. This will allow an explanation of the hydraulic behavior of this type of fishway under tailwater levels and flow variations on rivers. Two vertical slot fishways located in Duero River (North-Central Spain), subject to different hydraulic conditions, were studied for the validation of the proposed formulation. The observed values are consistent with the predicted results and, among others, demonstrate the importance of including variables that consider downstream water level. Consequently, the proposed discharge coefficients together with the algorithm have resulted in a method that enables the improvement of the performance of both existing and future vertical slot fishways. This will have major implications in real-life scenarios in which uniform operation conditions are rarely achieved.