Abstract
Under a changing environment, the current hydrological design values derived from historical flood data for the Three Gorges Reservoir (TGR) might be no longer applicable due to the newly-built reservoirs upstream from the TGR and the changes in climatic conditions. In this study, we perform a multivariate dam-site flood frequency analysis for the TGR considering future reservoir regulation and summer precipitation. The Xinanjiang model and Muskingum routing method are used to reconstruct the dam-site flood variables during the operation period of the TGR. Then the distributions of the dam-site flood peak and flood volumes with durations of 3, 7, 15, and 30 days are built by Pearson type III (PIII) distribution with time-varying parameters, which are expressed as functions of both reservoir index and summer precipitation anomaly (SPA). The multivariate joint distribution of the dam-site flood variables is constructed by a 5-D C-vine copula. Finally, by using the criteria of annual average reliability (AAR) associated with the exceedance probabilities of OR, AND and Kendall, we derive the multivariate dam-site design floods for the TGR from the predicted flood distributions during the future operation period of the reservoir. The results indicate that the mean values of all flood variables are positively linked to SPA and negatively linked to RI. In the future, the flood mean values are predicted to present a dramatic decrease due to the regulation of the reservoirs upstream from the TGR. As the result, the design dam-site floods in the future will be smaller than those derived from historical flood distributions. This finding indicates that the TGR would have smaller flood risk in the future.
Highlights
As the largest hydroelectric dam in the world, the Three Gorges Dam (TGD) is located at the dividing site between the upstream and midstream of the Yangtze River, which is the largest river in China
After 2003, the dam-site floods of the Three Gorges Reservoir (TGR) will be represented by the floods simulated according to Equation (1)
It is found that after 2003 the observed floods at Yichang gauging site are generally smaller than the simulated dam-site floods
Summary
As the largest hydroelectric dam in the world, the Three Gorges Dam (TGD) is located at the dividing site between the upstream and midstream of the Yangtze River, which is the largest river in China. The Three Gorges Reservoir (TGR) formed by the TGD has been put into operation and led to a profound impact on the hydrological regime downstream of the dam [1,2,3,4,5,6]. It is indicated that the inflow flood or the dam-site flood of the TGR is unavoidably regulated by the upstream reservoirs. Due to the regulation of the reservoirs in the upstream basin of the TGR, the dam-site floods of the TGR no longer follow a natural process [8,9]. Some studies have revealed that the hydrological regime of the inflow of the TGR has presented significant variations due to the regulation of the reservoirs upstream of the TGR [9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
