Numerical simulation of effects of inlet water depth of ecological fishway on the suitability of passing fish

Abstract

Ecological fishways can not only restore the free passages of migratory organisms, but also play the role of ecological corridor. Currently, the behavior and ecology of the target fish were not fully taken into account in the design of fishways. So this paper takes the swimming ability of Hueho taimen, Brachymystax lenok and Thymallus arcticus in Buhe River as indicators, presents a systematic numerical investigation on effects of different inlet water depth in ecological fishway using a three-dimensional hydrodynamic model (EFDC). The numerical results indicate that the inlet water depth is a key factor in the ability to pass fish. It is shown that the two schemes with different slopes and roughness have significant differences in the flow field distribution under the same inlet water depth; the differences are the location where the maximum velocity occurs and the range beyond the upper limit of the velocity. In addition, when the inlet water depth increases to 0.8m, the flow field distribution of both designs are more suitable for fish passage. The outcomes of this study will be helpful to improve the design of the entrance of Buhe River fishway and make the target species more suitable for passing through.