Regional water resources assessment using water scarcity pinch analysis

Abstract

Water quality problems contribute significantly to water scarcity. This study aims to redefine water scarcity caused by water quality degradation together with water quantity shortage and propose a Water Scarcity Pinch Analysis (WSPA) to quantify the regional water scarcity. WSPA is proposed based on the well-applied method of Water Pinch Analysis. The quality of water sources and demands is specified by setting water quality categories, based on which the staircase Grand Composite Curve (GCC) is constructed. After applying the water quality cascade, the GCC provides the water quantity-quality target, which is the net deficit volume (m3) of water with certain water quality (categories). The water quantity-quality target is defined as the regional water scarcity. Water quality upgrading is applied to maximise the water use efficiency for different purposes by mixing water sources with different qualities. Three case studies are set to illustrate the implementation of the proposed method and investigate the performance of the proposed WSPA. The results show that WSPA identifies both the water quantity scarcity and scarcity caused by insufficient water quality or the water quality mismatch between the sources and demands. Conclusions and novel contributions are i) WSPA enables accounting for water quality together with quantity in water scarcity assessment and provides both quantity and quality targets for minimising regional water scarcity; ii) Applying the WSPA to a macro level elevates the ratio-based water scarcity assessment from single determination to insight-based assessment that can guide the regional water resource management; iii) water quality cascade and water quality upgrade with water dilution can improve water use efficiency and reduce regional water scarcity.