西安市再生水补给河道水生态风险及调控策略研究

Research on Water Ecological Risks and Regulation Strategies of Reclaimed Water Replenishment Rivers in Xi’an City

摘要: 再生水补给是缓解北方缺水城市河道生态基流不足、改善城市水景观和水循环条件的重要措施，但长期补给可能伴随营养盐累积、藻类增长、微生物风险及河道生态功能弱化等问题。本研究以西安市再生水补给型城市河道为研究对象，于2024年5月至9月在上游对照段、再生水补给口、补给后混合段、景观滞留段和下游恢复段设置5个典型断面，选取pH、溶解氧、高锰酸盐指数、氨氮、总磷、总氮、叶绿素a和粪大肠菌群等指标，构建“水质指标–生态响应–风险分级–调控策略”的分析框架。结果表明，补给口及景观滞留段营养盐、叶绿素a和微生物指标相对较高，主控风险因子为总氮、总磷、叶绿素a和粪大肠菌群；下游恢复段经稀释、复氧和河岸带截留后风险有所降低。基于评价结果，提出源头提标、过程净化、生态修复和智慧监管相结合的调控策略，以期为北方缺水城市再生水生态补给及河道水生态修复提供参考。

Abstract: Reclaimed water replenishment is an important measure for maintaining ecological baseflow and improving urban river landscapes in water-deficient cities, but continuous replenishment may also cause nutrient accumulation, algal growth, microbial risks and weakened habitat functions. Taking reclaimed water replenishment rivers in Xi’an City as the research object, this study conducted monitoring from May to September 2024 at five typical sections, including the upstream control section, replenishment outlet, mixed section, landscape retention section and downstream recovery section. Indicators including pH, dissolved oxygen, permanganate index, ammonia nitrogen, total phosphorus, total nitrogen, chlorophyll-a, and fecal coliforms were selected, and an analytical framework of “water quality indicators, ecological response, risk classification, regulation strategies” was established. The results show that nutrient concentrations, chlorophyll-a and microbial indicators were relatively high at the replenishment outlet and landscape retention section, with TN, TP, chlorophyll-a and fecal coliform as dominant risk factors. The downstream recovery section presented reduced risks due to dilution, reoxygenation and riparian interception. A comprehensive strategy involving source upgrading, process purification, ecological restoration and intelligent supervision is proposed to support reclaimed water ecological replenishment and urban river restoration in northern water-deficient cities.