Leakage safety analysis of anti-seepage measures in reservoir basins: a case study of the Okinawa seawater pumped storage system in Japan

Abstract

As seawater pumped storage systems (S-PSSs) have attracted more global attention, the leakage of basins from upper reservoirs has been noted. The study of reservoir basin leakage is very important because this issue not only affects vegetation in shallow areas but also negatively affects the safety of the ecosystem and the engineering stability of the reservoir when seepage into groundwater occurs. This research aims to study seawater ion (chloride ion (Cl-) and total dissolved solid (TDS)) transport and movement laws in the Okinawa S-PSS reservoir basin and its engineering-derived seepage stability under different reservoir basin anti-seepage schemes. This study shows an anti-seepage scheme that effectively reduces leakage, lowers the infiltration line, and reduces the influence range of seawater ion migration. Under the anti-seepage scheme, the influence of range of seawater ion pollution is reduced by approximately 90%, and the safety factor is increased by 84%. Compared to reinforced concrete faces (RCFs), asphalt concrete faces (ACFs) are more suitable for engineering applications. This article verifies that the ethylene-propylene-diene monomer (EPDM) scheme for the upper reservoir almost entirely prevents leakage in the Okinawa S-PSS and provides relevant experience for the vast development of S-PSSs across China and the world.