基于GIS的鄱阳湖流域非点源吸附态污染物时空变化研究

鄱阳湖作为中国最大的淡水湖,国际重要湿地,其生态环境保护与可持续发展意义重大。基于GIS技术,以鄱阳湖流域为研究区域,利用3个时期多源数据,首先运用土壤流失方程估算鄱阳湖流域土壤侵蚀量,计算土壤侵蚀模数,然后根据泥沙输移比估算水体的泥沙负荷,最后采用颗粒态氮磷营养盐迁移经验模型定量研究鄱阳湖流域非点源吸附态污染物N、P负荷的时空变化规律。结果显示:吸附态氮磷污染负荷在空间分布上呈现出四周高、中间低的特点,相对较高的区域位于流域中、上游,这主要由于该区域多为山地陡坡;相对略低的区域位于流域的下游地区,这主要因为该区域平原和丘陵交错分布,土壤侵蚀强度较低。时间变化上,全流域单位面积N、P吸附态污染物负荷大都呈现先增加后减少的趋势,同时减少的幅度较增加的幅度大。

SPATIAL-TEMPORAL VARIATION OF NON-POINT SOURCE ADSORPTION POLLUTANTS IN POYANG LAKE WATERSHED BASED ON GIS

Poyang Lake is the largest freshwater lake in China and an important international wetland.The ecological environment protection and sustainable development of this lake basin have great significance.In this study,GIS spatial analysis is used to figure out the non-point source adsorbed pollutants (nitrogen and phosphorus) of this region,which based on multi-source data in 1990,2000 and 2008.Firstly,the soil erosion amount and modulus were estimated by the soil loss equation.Secondly,the lake sediments loadings were calculated by the sediments transferring ratios in the lake.Finally,the spatiotemporal variation of non-point source N and P loadings were simulated by Particulate N and P transfer empirical model.The results indicated that N and P pollutions were lower in the center but higher in surrounding areas.The pollutions were higher in the upper drainage areas but lower in lower areas,which was mostly due to the plains and hills are interactively distributed in this region and the low soil erosion intensities in this type of landforms.This region yearly N and P pollution order in the studied years is 2000 ＞ 1990 ＞ 2008.