Research on the synergistic effect of multi-reservoir flood control capacity by considering the conditional value-at-risk

The concept of conditional value-at-risk (CVaR) is introduced into the field of flood damage assessment, and a joint design method for multi-reservoir system flood storage based on CVaR is then proposed. The purpose of the method is to research on the mutual feedback mode for coordinated flood control among reservoirs by analyzing the degree of influence of each reservoir′s storage capacity on the flood control risk of the reservoir group system as a whole. The five-reservoir system of the Hanjiang River is selected as a case study, and the flood damage assessment index CVaR values corresponding to the present flood storage combination scheme (FSCS) are regarded as upper limit values. The results show that: ① The sensitivity rankings of the five reservoirs, in descending order, are: Sanliping, Yahekou, Danjiangkou, Ankang, and Pankou reservoirs. ② The flood damage assessment index CVaR values corresponding to different FSCSs may not be the same when the total flood storage of the multi-reservoir system is fixed as a constant, and there is a viable FSCS for the multi-reservoir system. ③ If the same CVaR constraint conditions are selected, the Danjiangkou Reservoir has greater flexibility to adjust its flood control capacity in the five-reservoir system than in the two-reservoir system, because the former considers the flood control coordination effect of more reservoirs (such as Pankou, Sanliping, Yahekou reservoirs).