洱海流域水环境问题诊断与水质保护措施研究

Study on diagnosis of water environmental problems and water quality protection countermeasures in Erhai Lake Basin

洱海是大理白族人民的集中饮用水水源地,具有湖泊水质演变过程复杂、面源污染治理难度大、流域水资源短缺程度逐步加重、湖滨带水生植物自然恢复缓慢等环境问题。分析了近年来洱海水质演变情况。按照新时代治水思路的要求,研究提出了高效节水生态农业、生态调蓄带末端拦截、外流域补水、优化洱海4~7月水位调度等措施,以加快洱海水生态系统的修复与水质的持续性改善。为此,构建了洱海水环境数学模型用于开展相关水质改善措施效果的数值模拟。结果表明:①高效节水农业可从源头上削减负荷30%以上;②生态调蓄带汇流区旱季和降雨初期的雨污水可被全部拦截并回用农田;③外流域补水可补齐流域水资源短板,使洱海年度水质改善1.29%~5.15%,并为洱海水位优化调度与湖泊水生态修复提供良好的水资源条件支撑。

Erhai Lake is a main drinking water source of the Bai ethnicity in Dali,Yunnan Province.There are some water environmental problems in Erhai Lake,such as the complicated evolution process of water quality,the difficulty to effectively control non-point source pollution,the aggravation of water resource shortage,and the slow natural recovery of submerged plants along the lakeside.According to the new thinking on water conservancy in the new era,this paper puts forward some targeted measures,such as facilitating the development of efficient water-saving agriculture,strengthening the end interception of pollutants by the ecological storage zones,carrying out projects to supplement water from other river basins,and optimizing the water level scheduling of Erhai Lake from April to July,which are keys to achieve Erhai Lake's sustainable improvement of water quality and water ecosystem as well.Therefore,this paper established amathematical model of water environment of Erhai Lake to carry out the numerical simulation of water quality improving measures.The results showed that the efficient water-saving agriculture could reduce more than 30% of the pollution loads from the source.The rain sewage in the confluence area during the dry season and the early rainfall period could all be intercepted and reused by the ecological storage zones.The water supplementation from other basins can make up the shortcoming of water resource shortage,to improve annual water quality of Erhai Lake by 1.29%~5.15%,which can provide a good water resources condition support for the optimal scheduling of water level and water ecological restoration in Erhai Lake.