Assessment of enhancement benefits on water environment resilience through reclaimed water and stormwater replenishment in rain-fed urban river systems

As China's economy soars and urbanization accelerates， the inadequate sewage treatment infrastructure has resulted in a deteriorating urban water environment， particularly evident in water pollution. The southern coastal hilly regions face seasonal water scarcity， making ecological replenishment of rivers crucial. This study targeted the Longgang River watershed in these regions， utilizing reclaimed water and reservoir water for ecological replenishment. By integrating a coupled hydrodynamic-water quality model with a reliability， resilience， and vulnerability （RRV） assessment framework， the study quantified the resilience enhancement from reclaimed water replenishment. The results revealed that after replenishment with reservoir water， river resilience improved consistently with reliability， with the latter demonstrating a more pronounced enhancement. Notably， uniform replenishment with non-potable reservoir water significantly boosted the resilience of less polluted rivers. Additionally， the resilience-enhancing effects of replenishment were more pronounced for chemical oxygen demand （COD） and ammonia nitrogen （NH3-N）， compared to total phosphorus （TP）. This study provides insights into optimizing water resource management strategies for resilient urban water environments.

伴随中国经济腾飞与城市化进程加速，污水处理基础设施建设不足导致城市水环境持续恶化，水污染问题尤为凸显。南方沿海丘陵地区面临季节性水资源短缺，河道生态补水因此显得至关重要。本研究以该区域的龙岗河流域为研究对象，采用再生水（reclaimed water）与水库水开展生态补水工作。通过将耦合水动力-水质模型与可靠性、恢复力及脆弱性（Reliability, Resilience, and Vulnerability, RRV）评估框架相结合，本研究量化了再生水补水对河道恢复力的提升效果。研究结果表明，采用水库水补水后，河道恢复力与可靠性同步提升，且可靠性的提升效果更为显著。值得注意的是，采用非饮用水源水库水进行均匀补水，可显著提升轻度污染河道的恢复力。此外，相较于总磷（Total Phosphorus, TP），补水对化学需氧量（Chemical Oxygen Demand, COD）与氨氮（Ammonia Nitrogen, NH3-N）的恢复力提升效果更为明显。本研究可为韧性城市水环境的水资源管理策略优化提供参考。