Economic and environmental sustainability of the optimal water resources application for coastal and inland regions

Abstract

Global water security threatens human health and urbanization, forcing communities to seek ways to tackle water stress problems. Alternative water resources including seawater, desalinated seawater, reclaimed wastewater and desalinated wastewater effluent can replace conventional surface freshwater. Considering alternative water resources, one problem facing policymakers is which one is the most feasible to use under their water and geographical conditions. This study aims to tackle this problem by analyzing the global sensitivity of key influential factors among water and geographic characteristics, assessing water supply systems for coastal and inland regions from both economic and environmental perspectives. The analyzed influential factors are effective population density, population served, daily water demand per capita, water demand of toilet flushing, distance to seaside, and water import distance. The global sensitivity analysis approach is utilized to evaluate the sensitivity index of the influential parameters with respect to each impact category. The analysis demonstrates that the most sensitive influential factors are effective population density and distance to the ocean. By further considering the conditions for extensively applying potential water resources, the analysis illustrates that seawater toilet flushing (SWTF) is the most environmentally friendly option even in areas far away from the seaside with relatively low population density. However, SWTF is only economical in coastal areas with density above 17 000 persons/km2. Wastewater effluent desalination is cheaper for other coastal regions with a lower population density and for inland regions.