Multi-objective decision and joint refill schemes of Xiluodu-Xiangjiaba-Three Gorges cascade reservoirs

In order to balance the contradictions between flood control and comprehensive utilization bene-fits and optimize the timing and process of refill synergistically,an integrated joint refill operation modelconsisting of a flood control risk analysis module used to derive maximum safety water level and risk,a uti-lization benefits analysis module used to analyze power generation and refill benefits and a multi-objectiveevaluation module used to evaluate flood risk, power generation and refillt benefits is proposed in thisstudy to derive joint optimal refill rules for cascade reservoirs. The Jinsha River and Three Gorges cascadereservoirs in the Changjiang River basin of China are selected for a case study. The results show that therecommended joint optimal refill schemes are synchronous scheme with start time of refill operation onSept. 5 as well as asynchronous scheme with start time of refill operation on Sept. 1,Sept. 5 and Sept. 10 for Xiluodu,Xiangjiaba and Three Gorges cascade reservoirs. Besides,joint optimal synchronous and asyn-chronous refill rules can generate 2.38 billion k W·h(3.25%) and 2.04 billion k W·h(2.78%) more annualaverage hydropower and improve fullness storage rate from 96.73% to 97.51% as well as 97.57% respective-ly for the cascade reservoirs without reducing originally designed flood prevention standards comparing withthe designed operating rules.