Using an Eco-hydrodynamic Model to Simulate the Impact of Trunk Dam Construction on Kraal River Fish Habitat and Community

Dam construction provide benefits to local communities including hydropower generation and flood protection, but also harms fish species by altering physical habitat and providing pollution during the construction process. Evaluating river reaches habitat suitability level may know how the habitat and which extent affected by dams. This study used a systems analysis approach to preliminarily evaluate habitat suitability level at before dam construction and during dam construction in Kraal River. A habitat model which included hydrodynamic and pollution transport was used to evaluate the Garra fish (Garra pingi) habitat suitability level affected by pollution produced by dam building system and living waste water. Flow velocity, water depth, riverbed substrates and pollution concentration were selected as suitability indicators. Numerical model simulations were undertaken as follows: Firstly, the water depth and velocity were simulated and the substrate distributions were also surveyed. The pollution concentration was simulated and the corresponding suitability indexes were calculated based on the fish preference curves. After that, the HSI distributions in both before dam building and during dam building were obtained and compared. The results shown that the pollution from dam building system were severely influenced the Garra fish habitat. It is worth noted that the habitat suitability can be recover when the discharge pollution concentration could reduce lower than 800mg/L.