2019 Volume 25 Issue 1 Pages 7-14
The influence of water abstraction for hydroelectric power generation on instream fish habitat was evaluated using a two-dimensional hydrodynamic simulation, the Habitat Suitability Index (HSI), Weighted UsableArea (WUA), and Weighted Suitable Area (WSA) in a midstream reach of the Anegawa River, Japan. The study reach is affected by upstream dam flow regulation and water withdrawal for hydropower generation. The unsteady two-dimensional hydrodynamic model was calibrated and validated with observed data from 2015 and 2016. The reach’s habitat quality was assessed for the adult goby (Rhinogobius flumineus) and dark chub (Nipponocypris temminckii) by combining computed hydraulic variables and suitability indices for the given species. Analysis of the spatial HSI distribution and the WUA and WSA variations under discharges ranging from 0.1 – 40 m3/s revealed that both WUA and WSA for goby tended to be larger than those of dark chub. Water abstraction had opposite effects on goby and dark chub during their spawning months. These results, including the flow curves developed here, could inform improved future management of the flow regime in this and other Japanese rivers.
