水源区河流非点源污染物入河量计算的水质方程反演方法

Inversion Formula of One-dimensional Water Quality Equation for the Export Loads of Nonpoint Sources Pollution in Headwater Area

以水质一维流方程为基础,建立了水源地区非点源污染物入河量计算的反演模型;计算了浙江省湖州市老虎潭水库水源地区各条支流的非点源污染物入河量;并通过对实测水文水质参数的统计,采用Monte Carlo模拟方法,分析了模型各输入参数的敏感性.由于该模型所有敏感参数都可以实测获得,避免了关键参数取值的人为主观因素的影响,保证了非点源污染过程定量分析的客观性;该模型在计算非点源污染物入河量时不受时间的限制,可以根据研究区域的水文水质监测频率计算任意时段内的非点源污染物入河量.结果表明,该水源区所有溪流中的氮、磷污染物负荷量都与溪流流量呈极显著正相关(r>0.90,p<0.01),因此,丰水期是非点源污染物入河的集中期;对输入参数的敏感性分析显示,对模型输出结果影响最大的是溪流的流量,其次是段末浓度和背景浓度,综合降解系数和流速的影响较小.

An inversion formula for the export loads of nonpoint sources pollution in headwater area was established based on one-dimensional water quality equation,and it was used to calculate the pollution loads for tributaries in the headwater catchment of Laohutan Reservoir,in Huzhou City,Zhejiang Province of China.Monte Carlo method was adopted to determine the sensitivity about each input parameter in the inversion formula.Because each sensitive parameter can be measured directly in the inversion formula,so that this approach can decreased calculation error,which is often caused by the parameter estimation.Furthermore,the inversion formula can be adopted to calculate pollution loading on any time scale.Monthly nonpoint sources pollution export loads in 2007 were calculated by the model in the research catchment.Results showed that pollution loads in stream were significantly positive related with flow rates（r 0.90,p 0.01）,and the flow rate was the most sensitive factor in the model,followed by the nutrient concentration and background concentration at the stream end.While,comprehensive degradation coefficient and flow velocity contributed very little influence to the model uncertainty.