Impacts of Inter-basin Water Diversion Projects on the Feedback Loops of Water Supply-Hydropower Generation-Environment Conservation Nexus

Abstract. To balance water resource distribution among different areas, inter-basin water diversion projects (IWDPs) have been constructed around world. The unclear feedback loops of water supply-hydropower generation-environmental conservation (SHE) nexus with IWDPs increase the uncertainty in the rational scheduling of water resources for the water receiving and water donation areas. To address the different impacts of IWDPs on the dynamic SHE nexus and explore collaborative states, a framework was proposed to identify these impacts across the multiple temporal and spatial scales in a reservoirs group. The proposed approach was applied to the Hanjiang River Basin (HRB) in China as a case study. Multiple temporal and spatial scales runoffs from HRB were provided through the Variable Infiltration Capacity hydrological (VIC) model. And multi-level ecological flows and their corresponding multi-level ecological flow standards were also determined by the Modified Tennant Method Based on Multilevel Habitat Conditions (MTMMHC) method. 30 scenarios were set and modeled in a multisource input-output reservoir generalization model. Differences between scenarios were quantified with a response ratio indicator. The results indicated that: there are negative feedbacks between water supply (S) and hydropower generation (H), between S and environmental conservation (E) while positive feedbacks between H and E without IWDPs. The negative feedbacks of S on H and the positive feedbacks of E on H are weakened or even broken in abundant water periods. Water donation has negative impacts on feedback loops, while water receiving has positive impacts on these feedbacks. Feedback loops exhibit intrinsic similarity and stability across different time scales. Feedbacks in reservoirs with regulation function remain stable under the varying inflow conditions and feedbacks for downstream reservoirs are influenced by their upstream reservoirs, especially in low flow periods. The proposed approach can help quantify the impacts of IWDPs on SHE nexus and contribute to the sustainable development of SHE nexus.