基于“径流-地类”参数的非点源氮磷负荷估算方法

东江作为广东省重要的饮用水源,其上游农业集水区非点源氮磷流失量备受关注.因此,本文以东江上游上莞河小流域为研究区,利用2011年的集水区水质监测数据,在平均浓度法及输出系数法的基础上,构建基于"径流-地类"参数的非点源氮磷负荷计算式,其径流、地类参数分别通过校正后的SCS模型和土地利用现状图获取,并分别对上莞河流域及流域各地类的非点源氮磷流失量进行估算.研究结果表明,汛期上莞河流域氮磷流失量主要来源于非点源污染,其非点源氮、磷流失量分别占氮、磷流失总量的97.32%、98.05%.坡度对流域非点源氮磷流失影响较小,地类是影响非点源氮磷输出的重要因素.构建的计算式能较好地估算非点源氮、磷负荷量,在次暴雨尺度非点源氮、磷输出量模拟精度分别为84.78%、81.06%.2011年度上莞河流域非点源氮、磷输出量分别为48923.4、7189.3 kg,耕地、居民地分别是非点源氮、磷输出的关键源区,其非点源氮、磷输出量分别占流域非点源氮、磷输出总量的84.20%、58.54%.

Estimation of agricultural non-point source nitrogen and phosphorus load based on rainfall-runoff and landuse types

Dongjiang River is one of the important drinking water source areas in Guangdong province, and the nitrogen and phosphorus losses from the Dongjiang upstream have achieved much concern in recent years. A small catchment of the Shangwan River basin, located in upstream of Dongjiang River, was selected in our study. Using the monitoring dataset in 2011, the parameters of runoff and land use types were derived from SCS model and land use maps, and the "runoff-land use type" based non-point source load equations were constructed using mean contents and output coefficient for the elements. The nitrogen and phosphorus losses of non-point source were then assessed using the constructed equation, and meaningful results were obtained in our paper. In 2011, 97.32% of nitrogen and 98.05% of phosphorus loss came from non-point source pollution in rainy reason, and the influence of land use types was larger than that of topography. The mean simulation accuracies of nitrogen and phosphorus loadings for single rainfall event were 84.78% and 81.06% respectively. Cultivated land and settlement were regarded as the main source of nitrogen and phosphorus pollution area. In 2011, the estimated nitrogen and phosphorus loading were 48923.4 kg and 7189.3 kg, respectively. The non-point source nitrogen and phosphorus loads from these two areas occupied 84.20% and 58.54% of the total for the study catchment.