The impacts of the wetness–dryness encountering of the upstream inflow and downstream salt intrusion on water supply in coastal urban agglomeration

Abstract

Abstract In the current study, to investigate the impacts of the wetness–dryness encountering of the upstream inflow and downstream salt intrusion on the water supply of the Pearl River Delta, we developed a water evaluation and planning (WEAP)-based water resources allocation model to calculate water supply schemes for the Pearl River Delta under 10 different scenarios. The impact of the scenarios on the water supply scheme of the Pearl River Delta was investigated. The results showed that (1) the water shortage of the Pearl River Delta is highly dependent upon the dryness combination of the upstream runoff during the dry period, in particular to the cities at the Pearl River Delta estuary, the water shortages are seriously influenced by saltwater intrusion; and (2) the water transfer projects could alleviate the water supply pressure of the Pearl River Delta when there is an extreme or more dryness encounter of upstream runoff. However, when extreme dryness events are impacting the upstream runoff of the West River, the impact of the water transfer projects is weakened and much of the critical upstream runoff for saltwater suppression cannot be satisfied, which largely impacts water withdrawals at the downstream cities in the Pearl River Delta estuary.