Quantifying basin water balance considering water-economic society-ecology nexus

Abstract

This study proposes a set of methods for quantifying Basin water balance (BWB) in the context of the Water-Economic society-Ecology nexus. Firstly, a theoretical analysis of BWB is conducted, identifying three key aspects that should be considered: Water budget balance (WBB), Water supply–demand balance of economic society (ESWSDB), and Water use balance between economic society and ecology (EEWUB). Secondly, a distributed human-water relationship simulation model was developed, which aligns with the dual water cycle processes of nature and society. Thirdly, targeted methods for various aspects of BWB, along with a comprehensive approach for quantifying BWB, are proposed. Finally, the Qin River Basin in China was selected for a case study covering the period from 2001 to 2022, revealing the state and characteristics of BWB across multiple scales, levels, and dimensions. Results show that: a) during the study period, the WBB of the basin was generally in a slight imbalance state, characterized by decreasing water storage, with the imbalance deteriorating progressively from upstream to downstream; b) the average balance index of ESWSDB is 0.161, indicating an overall trend towards water surplus, but with significant differences in balance state and index across different basin zones; c) the average balance index of EEWUB was −0.168, indicating a slight water deficit on the ecological side, with river runoff during average and low-flow years being insufficient to simultaneously meet both economic-social and ecological water needs; d) overall, the BWB state still has room for improvement and is largely influenced by the WBB and ESWSDB during periods of poor balance state. Findings can enhance the understanding of BWB and offer valuable insights for global water balance quantification, contributing to the management of human-water relationship.