苕溪入湖污染物通量计算及区域污染物影响权重分析

Calculation of flux of inflow pollutant and analysis of weight of influence of pollutant from different districts in Tiaoxi

为研究苕溪流域入太湖污染物通量的时空变化特征规律,在苕溪流域水文水质同步监测基础上建立一维水动力水质数学模型。利用经率定验证的苕溪流域模型,结合枯水年P=90%(2003年型)、平水年P=50%(1995年型)、丰水年P=20%(1981年型)的水文资料以及2011年流域主要污染物排放资料,计算各典型年的入太湖污染物通量。通过出入区县交界断面河流通量的计算,进一步分析跨区域污染物影响的权重,为污染物溯源做铺垫。结果表明:1污染物因子COD、NH3-N、TP、TN的入湖通量丰水年依次为29111、1828、347、6712 t/a;平水年依次为21297、1248、272、6087 t/a;枯水年依次为14 243、898、187、407 8 t/a,各污染物因子丰水年和平水年的入湖通量较大,枯水年较小;2不同典型年各区县污染物因子对入湖通量影响权重由大到小排序依次为吴兴区(部分)、德清县(部分)、安吉县、临安市、余杭区(部分),对吴兴区的污染治理是苕溪流域入湖污染治理的关键所在。

In order to study the characteristic and regular of spatial and temporal variation of flux of Taihu Lake inflow pollutant in Tiaoxi Basin, one-dimensional hydrodynamic and water quality model is established based on synchronous monitoring of hydrology and water quality in Tiaoxi Basin. According to hydrological data from a dry year P=90% （2003）, a normal year P=50% （ 1995）, and a wet year P=20% （ 1981 ）, and data of pollutants discharge in 2011, the flux of inflow pollutant in each typical year was calculated using the validated model of Tiaoxi Basin. Further analysis of the effect weight of cross-regional pollutant was done according to the calculation of the pollutant flux in rivers which run in or out of the district. Thus the foundation of tracing the source of pollutants was established. The results indicate that： （1） The flux of inflow pollutant component of COD, NH3-N , TP,TN in wet years are 29111,1 828,347,6712 t/a, respectively ;in normal years are 21297,1 248,272,6087 t/a, respectively;and in dry years are 14 243,898,187,4078 t/a, respectively. The flux of inflow pollutant in wet years and normal years is larger, while in dry years it is smaller; （2） The weights of influence of inflow pollutant from each district in different typical years are ordered from large to small as follow： Wuxing District （partly） ; Deqing County （partly）; Anji County; Linan City; Yuhang District （partly）. Therefore, pollution control of Wuxing district is the key to inflow pollution control in Tiaoxi Basin.