The importance of design in river fishways

The main objective of this work is showing how numerical simulation and optimal control theory can be useful tools in practical ecological engineering. We take attention into diadromous fish (salmon, trout, eel…) and their river migrations, and particularly, we focus on fishways, hydraulic structures that enable fish to overcome stream obstructions as dams or weirs. We use mathematical modelling to formulate the problems of design and management of a fishway providing a good hydraulic performance for fish. By solving these problems for a standard vertical slot fishway, we can observe that controlling the flux of inflow water is a useful technique for the management of an already built fishway, but a correct shape design is mandatory in order to guarantee a correct hydraulic performance, especially for a new fishway.