受全球气候变化的影响, 暴雨洪水事件发生频率呈增加趋势, 水库作为流域内重要的控制性水利工程, 洪水过 程中水质安全面临严重威胁。以碧流河水库为例, 对建库以来 7 场典型洪水前后水质状况进行分析, 结果表明, 洪 水过程能够减弱碧流河水库水体的热分层结构, 影响溶解氧垂向分布; 洪水过程影响较大的水质指标为六价铬、大 肠菌群、高锰酸盐指数、氨氮和总磷, 洪水过后上升趋势较为明显; 空间上来说, 洪水对入库口断面的影响大于对坝 前断面的影响, 碧流河水库地形特征能够减弱洪水异重流对坝前水质的影响; 评价结果显示洪水过后碧流河水库水 质变差, 但整体上能够满足地表水环境质量标准中水源地要求; 洪水期间入库污染物主要来自流域非点源污染。分 析认为, 通过源头治理、入库口拦截、合理调度等措施可以减轻洪水事件对水库水质的影响。

The frequency of ex tr eme floo ds is increasing due to t he impact of g lo bal climate chang e. Reser voirs, as an important water co nser vancy project , suffer ed fr om serious w ater qualit y problems during flo od ev ents in the river basin. This study too k the Biliuhe r eser vo ir as an example and analysed the water quality data befo re and after seven flo od events since the dam w as co nstr ucted. T he r esults show ed that floo ds could w eaken the thermal str atification o f the Biliuhe reser voir and influence the vert ical distribution of disso lv ed ox yg en. Flood ev ents had gr eat impacts o n water quality v ariables of hex avalent chrom ium, coli2 fo rm bacteria, permang anate index , ammonia and t otal phospho rus, w hich had incr eased aft er the floo d event. In terms of spatial distribut ions, the concentr ation of po llutants at the entr ance section of t he r eser vo ir w as gr eater than the fr ont of the dam. T he topog raphic characteristics o f the Biliuhe r eser voir could w eaken the impact of floo d density flow o n the w ater quality in fro nt of the dam. T he assessment results indicated that the w ater qualit y gr ade of the r eser voir become w orse after the flood, but it meet the env iro nmental quality standards for surface water. The po llutants ent ering the reserv oir during f loo ds mainly come fr om the no n2point so ur ce pollution in the Biliuhe r eser vo ir basin. The countermeasur es such as contro lling non2point so ur ce po llutants, intercept ion at the entr ance o f the reservo ir, reasonable r egulation during flo ods pro cess could alleviate the im pact of floo d e2 v ents on the wat er quality o f the Biliuhe r eservo ir.

国家重点研发计划 ( 2016YFC0400903) ; 国家自然科学基金( 51679026; 51809032; 51879031)