土地利用/覆盖变化对长江上游非点源污染影响研究

在国内外相关研究的基础上,利用输出系数模型,结合RS和GIS技术,对长江上游的非点源污染负荷进行了空间模拟和负荷估算.模拟结果表明,在不考虑流域损失的前提下,由于土地利用造成的非点源污染负荷TN总量从20世纪70年代的123万t下降至2000年的116万t,基本呈逐年减少的趋势,由土地利用造成的TP的变化趋势与TN基本相同,从70年代的3.7万t下降到2000年的3.5万t左右.就省份、土地利用类型和水系而言,四川省、种植用地和草地以及金沙江水系和嘉陵江水系对长江上游的非点源污染贡献较大.在非点源污染负荷强度上,重庆市和嘉陵江水系单位面积负荷最高,是今后应重点治理的地区.结果表明,该模型可以对长江上游这样的超大尺度空间的非点源污染进行较好的空间模拟.

Effect of Land Use/Cover Change on Pollution Load of Non-Point Source in Upper Reach of Yangtze River Basin

On the basis of other scholars' researches,utilizes export coefficient model,adopts RS and GIS techniques,estimates the non-point source(NPS) pollution load of upper reach of Yangtze River Basin,and simulates its special distribution.The results indicates that the total nitrogen load caused by land use drop from 1.23×10⁶ tons in 1970s' to 1.16×10⁶ tons in 2000 on the premise of taking no account of basin loss.It reduced year by year basically in the past several decades and so did TP load which decreased from 3.7×10⁴ tons in 1970s' to 3.5×10⁴ tons in 2000.As far as province,land use and water system are considered,Sichuan province,crop land grass,Jinsha river and Jialing river are important contributories of NPS pollution load in study area.Intensity analysis shows the region of Chongqing municipality and the watershed of Jialing River are two highest NPS pollution load areas,and these areas should be gained more attention in the future.Using the method put forward in this paper,NPS pollution space simulation is carried out in large scale basin such as upper reach of Yangtze River Basin precisely basically.