Reliability of Emergency Water Supply for a Reservoir and Enhancement through Floating Photovoltaics in a Long-Distance Water Diversion Project

Abstract

An emergency water supply is occasionally necessary for a reservoir; its reliability should be investigated. The operation schemes of reservoirs mainly consider the long-term normal water supply; the emergency water supply has been less studied. Floating photovoltaics (FPVs) can be set on the open canals of water diversion projects (WDPs) to decrease evaporation loss and save water for the emergency water supply for connected reservoirs, the effects of which must be quantified. Thus, a framework of reliability for the emergency water supply of a reservoir (REWS) is proposed in this study, including stochastic simulation of reservoir operation schemes, a set of objectives for an emergency water supply, and quantification of the REWS. The Danjiangkou reservoir (DR) is considered as a case study; it is the water source of the Han River and middle route of the South-to-North Water Diversion Project (MRSNWDP). The effects of FPV coverage above the MRSNWDP on water evaporation and the REWS have been reported. The results show that the REWSs are 37.6%, 45.5%, and 56.5%, respectively, for the average, 75% probability, and 95% probability water diversion schemes of the MRSNWDP. After setting the FPV system, the annual evaporation of the MRSNWDP was reduced to 1.15×107 m3 (−74.7%), increasing the REWS to 49.6% (+12.0%), 53.4% (+7.9%), and 61.3% (+4.8%) for the average, 75% probability, and 95% probability water diversion schemes of the MRSNWDP, respectively. The REWS framework is useful for reservoir operation and water resource planning. FPV coverage is suggested for WDPs with open canals.