TMDL管理模式用于农村小流域水环境治理

Application of TMDL Management Mode in Water Environment Treatment of Rural Watersheds

为了改善巢湖水质,选取巢湖流域典型农村小流域——石茨河流域作为研究对象,在对该流域进行水文和水污染分析的基础上,构建HSPF流域模型对其负荷和水质进行计算,根据确立的污染分配原则对负荷进行削减,以满足考核断面水质达标要求,并计算得到石茨河流域最大日负荷总量(TMDL),同时提出流域水质管理建议。结果表明,石茨河干流各水质指标(COD、NH_(3)-N与TP)均超出考核标准(地表水Ⅲ类标准);流域污染源中点源除明确排口管控外,还需重点关注镇区难以收集的散排点源,面源需重点关注集镇、村庄、工业用地与稻田等地块单元。经计算,在满足石茨河考核断面水质达到地表水Ⅲ类标准时,COD、NH_(3)^-N与TP允许排放的污染物量分别为1 196.31、30.25、2.43 kg/d;同时,从空间和时间角度提出分区和分阶段管理模式,以实现水质稳定达标。

In order to improve the water quality of Chaohu Lake,Shici River basin,a typical rural watershed in Chaohu Lake basin,was selected as the research object.Based on the analysis of hydrology and water pollution in the basin,a HSPF basin model was established to calculate its load and water quality.The total maximum daily load(TMDL)of the Shici River basin was reduced according to the principle of pollutant distribution,so as to meet the water quality standard of the assessment section.Basing on the TMDL,suggestions on water quality management of rural watersheds were put forward.The results showed that the water quality indicators COD,NH_(3)^-N,and TP in the main stream of the Shici River exceeded levelⅢin Environmental Quality Standards for Surface Water(GB 3838-2002).In addition to clear discharge control,point pollution sources of the basin should also focus on scattered point sources that are difficult to collect in towns,while non-point sources should focus on the land uses of town,village,industry and agriculture.According to the calculation,the allowable pollutant discharge of COD,NH_(3)-N and TP were 1196.31 kg/d,30.25 kg/d and 2.43 kg/d,respectively,for the water quality of Shici River assessment section to meet the levelⅢstandard stably.Meanwhile the zoning and stage management mode from the perspective of time and space is proposed to achieve the stable water quality.