Impact of the Yalong-Yellow River water transfer project on the eco-environment in Yalong River basin

Abstract

The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year. The Yalong River will be dramatically impacted hydrologically and ecologically because more than 60% of the runoff will be diverted. An ecohydrological model was used to evaluate the impacts of the project on river corridor and wetland in this study. Schizothorax is a typical plateau river species and was used as the indicator species for assessment of the impact of water transfer project. The model simulated the habitat area of Schizothorax in the reach between the Reba Dam and the Ganzi Hydrology Station on the Yalong River. The Reba Dam, A’an Dam and Renda Dam will be constructed in the Yalong River for enhancing the water level for water diversion into the Yellow River. The velocity, channel width, runoff, and water depth will be reduced due to the water transfer, especially during flood season. The reduction in the velocity, channel width, runoff and water depth will occur mainly in the reach near the three dams and the reduction will be reduced to a minimum level in a distance about 100 km downstream of the dams. The maximum net water loss of Kasha Lake is only 1197200 m3, only 0.3% of runoff flowing into the lake. The project cannot bring adverse effect on the lake. The habitat area of Schizothorax in the Yalong River might be reduced if the water was transferred from the Reba Dam. The habitat area of this species will be reduced more than 40%.