Spatial equilibrium-based multi-objective optimal allocation of regional water resources

Study region: Guangdong Province in China.Study focus: Water shortages due to the spatially uneven distribution of water resources have become the main obstacle to the sustainable development of regional society and the economy. To alleviate this problem, this study developed a framework including prediction, optimization, and decision-making models to allocate available water resources among the different sectors of the cities in the region. The framework was advantageous in efficiently predicting future water de-mand and supply for multiple cities, quantitatively reflecting the level of the spatial equilibrium of water allocation (SEWA) through coupling coordination degree (CCD), and achieving a higher level of SEWA rather than just the equitable water distribution.New hydrological insights for the region: The results indicated that: (i) by 2030, the deficit of water supply and demand of Guangdong Province would be further aggravated, with a water shortage rate of 4.18%; (ii) by optimal water allocation, the water shortage rate of Guangdong Province decreased to 1.56% and the level of SEWA improved significantly from moderate equilibrium to good equilibrium; and (iii) from 2018 to 2030, key water-saving sectors in different cities were identified, while the industrial sector had a higher water-saving intensity than other water use sectors. This study could provide references for integrated water allocation strategies to realize the coordinated development of socioeconomic and environmental systems in other regions of the world.