太湖上游流域下垫面因素对面源污染物输出强度的影响

应用流域断面监测、GIS的流域空间分析等手段建立太湖上游地区流域基础数据,通过多元逐步回归和冗余分析(redundancy analysis, RDA)手段,研究了太湖上游流域下垫面要素对流域出口污染物输出影响特征以及不同要素影响的相对强度,提取了影响太湖上游流域面源污染产出的主要下垫面因素并分析各小流域水质控制性要素的空间特征.研究结果表明,流域面源污染与下垫面要素具有很大的相关性,其中流域土地利用对面源污染产出的影响最为显著,其次是流域土壤特征、流域坡度,流域面积的影响最小;影响流域面源污染输出变化的控制性因素为居民用地、耕地面积比例和流域平均坡度,对水质数据进行解释的显著性和重要性水平均较高,能解释59.5%的流域水质信息、98.6%的下垫面特征-水质指标关系信息,且在不同小流域中这3个因素对流域水质影响的贡献率不同.

Influence of Landscape Characteristics on Non-Point Source Pollutant Output in Taihu Upper-River Basin

Based on the observed data in monitored drainage areas and GIS spatial analysis tools, watershed basic database of Taihu upper-river basin was built. Using the methods of multiple stepwise regression and redundancy analysis, the influence of landscape characteristics on non-point source pollutant output at the outlets of watersheds and their relative influence intensity were analyzed. The dominant landscape characteristics influencing non-point source pollutant output in Taihu upper-river basin and sub-watersheds were also illustrated. The results show that there are strong correlations between non-point source pollution and landscape characteristics, in which land use makes the most remarkable effect, followed by soil characteristics and average slope and watershed area in turn. Residential land proportion, farmland proportion and average terrain slope with higher importance and significance level, are the dominant landscape characteristics variables affecting non-point source pollutant output of watersheds. 59.5% of water quality information and 98.6% of relation information between landscape characteristics and water quality can be explained by these three variables. Furthermore, the contribution rates of these three landscape characteristics to non-point source pollutant output in each sub-watershed are different.