巢湖地区无监测资料小流域面源磷污染输出负荷时空特征

在来自工业和城镇生活污水的点源污染得到有效控制的状况下,面源磷污染正逐步成为湖泊和河流富营养化的主导因子.在缺少监测资料的流域,移植处于同纬度和具有相同自然条件的流域的模型参数,是开展SWAT模型模拟的有效方法.因此,本文以巢湖地区的柘皋河小流域为例,通过移植率定好的模型参数,运用SWAT模型分析研究区面源磷污染输出负荷的时间变化和空间分布特征.结果表明,1980—2012年面源磷污染负荷围绕着平均值上下波动,不同水平年的磷污染负荷有较大差异,其中,1996—2012年的面源磷污染的年负荷大于1980—1995年的磷污染年负荷.两个时期内不同月份的总磷负荷均有显著性差异,其中,6—8月的磷污染负荷较大.两个时期的面源磷负荷的空间分布存在一定的差异,1996—2012年单位面积的面源磷负荷明显大于1980—1995年的单位面积面源磷负荷,其中,面源磷负荷的增加主要集中在水田区域.土地利用类型的变化和化肥的大量使用是导致研究区面源磷污染负荷增加的主要因素.

Temporal and spatial characteristics of diffuse phosphorus pollution in the watershed without monitoring data at Chaohu Lake

As point source pollution from industry and domestic sewage is under effective control, diffuse phosphorus pollution becomes the dominant factor of lake and river eutrophication in China. In the watershed without monitoring data, it is a widely accepted solution for the modeling application to refer parameters of the watershed with similar latitude and natural characteristics. In this study, SWAT (Soil and Water Assessment Tool) model with the referred parameters was used to analyze the temporal and spatial variation regularity of diffuse phosphorus pollution loading in Zhegao river basin at Chaohu lake. The yearly diffuse phosphorus pollution loading during 1980 to 2012 fluctuated with large differences. The yearly diffuse phosphorus pollution loading during 1996 to 2012 was larger than that during 1980 to 1995. Considerable differences were identified on the monthly diffuse phosphorus pollution loading in those two periods. The monthly diffuse phosphorus pollution loading from June to August was larger among twelve months of a year. There was also a difference on the spatial diffuse phosphorus pollution loading between the two periods. Compared with the loading during 1980 to 1995, the spatial diffuse phosphorus pollution loading during 1996 to 2012 was much larger. The increase of the spatial diffuse phosphorus pollution loading was mainly reflected in paddy land. Landuse change and wide application of fertilizer were major factors which led to increase of diffuse phosphorus pollution loading in the study area.