With the continuous expansion of the planning and construction scale of pumped storage power stations

project site selection inevitably involves karst areas with complex geological conditions.Taking the lower reservoir of a pumped storage power station located in a karst region with developed composite fold structures as the research object

this paper analyzes the seepage problems of the lower reservoir and explores the influence of composite fold structures on reservoir seepage.The research results show that the reservoir suffers from multiple seepage issues

including reservoir bottom seepage

left bank seepage

right bank seepage and dam foundation seepage.Composite fold structures significantly increase the risk of reservoir seepage by aggravating the degree of karst development and forming complex lithological and structural combinations.