珠江三角洲城市非点源COD影响因素分析及其负荷估算

Estimation of Urban Non-Point Source Pollution Loading and Its Factor Analysis in the Pearl River Delta

珠江三角洲地区城市河流污染严重,非点源污染物入河量不容忽视.分别于2009～2010年对广东省佛山市汾江河流域的8个典型城市内河涌进行了降雨径流水质监测,并测算次降雨时段内非点源化学需氧量(COD)的入河量.综合平均浓度法及输出系数法的径流、地类要素,并通过校正后的SCS模型和土地利用现状图获取其径流量及地类参数,构建基于"径流-地类"参数的非点源COD负荷计算式.结果表明,降雨、地类是影响河涌集水区非点源COD负荷量的重要因素,且降雨对非点源COD负荷量的影响要大于地类.构建的计算式能较好地估算非点源COD负荷量,其对于单次降雨非点源COD负荷量的平均模拟精度为75.51%,且大时间尺度的模拟精度要优于次降雨尺度.据估算,2009年汾江河流域非点源COD的负荷总量及负荷强度分别为8 053 t、339 kg·(hm2.a)-1,其中厂矿地类的非点源COD负荷量及负荷强度最大.流域内非点源COD污染较为严重,应予以重视.

In the Pearl Delta region,urban rivers have been seriously polluted,and the input of non-point source pollution materials,such as chemical oxygen demand（COD）,into rivers cannot be neglected.During 2009-2010,the water qualities at eight different catchments in the Fenjiang River of Foshan city were monitored,and the COD loads for eight rivulet sewages were calculated in respect of different rainfall conditions.Interesting results were concluded in our paper.The rainfall and landuse type played important roles in the COD loading,with greater influence of rainfall than landuse type.Consequently,a COD loading formula was constructed that was defined as a function of runoff and landuse type that were derived SCS model and land use map.Loading of COD could be evaluated and predicted with the constructed formula.The mean simulation accuracy for single rainfall event was 75.51%.Long-term simulation accuracy was better than that of single rainfall.In 2009,the estimated COD loading and its loading intensity were 8 053 t and 339 kg·（hm2·a）-1,and the industrial land was regarded as the main source of COD pollution area.The severe non-point source pollution such as COD in Fenjiang River must be paid more attention in the future.