Identifying fish ecological risk patterns based on the effects of long-term dam operation schemes

Abstract

River regulation patterns play a key role in ecohydrology and they directly affect hydrodynamic variables, fish habitats, and fish abundance conditions. In the Kraal River, the Trunk Dam is currently being constructed and very little is known about the dam construction and operation impacts on fish species. In this study, an ecohydraulic model was built and linked to hydromorpho-dynamic, fish habitat, and fish abundance simulations. Two fish species, schizothorax (Schizothorax) and schizothorax (Racoma), representing a main and an endangered fish species, respectively of the Kraal River, were studied; their habitats and abundance statuses were predicted and analyzed based on four different long-term dam operation scenarios. Fish-friendly river regulation scenarios were also examined. The temporal- and spatial-scale hydro-morphodynamic results indicate that the erosion effects are much more significant than the deposition effects. Our study suggests that habitat destruction and fragmentation existed for all presented river regulation scenarios. The analysis indicates that long-term river regulation will result in a decrease in the fish population. However, there will be different levels of decline for fish habitats and populations depending on the dam operation scenarios. This study contributes to a better understanding of the dam-induced temporal habitat fragmentation and response of fish communities. This study also provides quantitative evidence for suitable river regulation scenarios and fish stocking strategies, which can help the fish community recover to a stable level.