Integrated control of mountainous lake in watershed scale: the effects and evaluation

以山地城市湖泊龙景湖为研究对象,通过污染物来源分析、分区水环境容量解析、污染负荷削减量预测,筛选出了龙景湖水质改善的TN、TP两个约束性水质指标,提出了流域尺度的湖泊综合治理模式,确定了龙景沟、赵家溪、园博园区和湖体四大治理区域,进而明确了各区域主要污染物的削减分配量。在此基础上从2013~2014年开展了包括流域面源污染治理、污染水体修复等多项水环境综合治理项目。2012~2015年对水质的连续监测结果表明,工程实施后(2015年)全湖TN平均浓度相比工程实施前(2012年)降低了45%,TP降低了50%,NH_3-N降低了62%。综合治理工程实施后,TN、TP的削减量显著高于为实现Ⅳ类水质目标需要削减的污染物负荷量。A case study was conducted in mountainous lake(Longjing Lake).Based on pollutants source analysis,water environmental capacity apportionment and pollutant reduction allocation, total nitrogen(TN)and total phosphorus(TP)were revealed to be the most imperative parameters that influence the water quality of Longjing Lake,the watershed scale control of lake was proposed,four control sectionincluding Longjing stream,Zhaojia stream,Expo Garden and lake water were determined,consequently the allocation of pollutant reduction were calculated.Afterward several projects including the control of non-point source pollution and restoration of the polluted water were conducted during 2013-2014.The water quality monitoring program during 2012-2015 indicated that the TN,TP and NH_3-N were reduced by 45%,50%and 62%,respectively, after the implement of the integrated projects.The amount of reduced TN and TPwere significantly higher than the proposed amount for the maintenance of the water quality for Grade IV