长江上游流域土地利用对面源污染影响及其差异

基于遥感与地理信息系统技术,对比分析了长江上游流域2000—2006年土地利用变化;利用输出系数模型,计算了土地利用引起的面源污染负荷,并从面源污染TN和TP负荷量、负荷强度和不同来源等角度,综合分析得出长江上游流域土地利用变化对面源污染影响及其差异。2000—2006年,长江上游流域耕地面积减少约1.10×104km2,林地面积增加约1.10×104km2,其他土地利用变化很小,表明西部大开发以来,天然林资源保护、长江防护林和退耕还林等工程实施效果明显。长江上游流域土地利用造成的TN和TP负荷量2000年分别为114.14×104t和3.39×104t,2006年分别为111.21×104t和3.31×104t。四川省西北部雅砻江中游流域、大渡河上游流域、岷江上游流域和贵州省北部乌江中游流域,2000—2006年面源TN和TP负荷显著减少。

Diversity and Effect of Diffuse Source Pollution Load Caused by Land Use Change in the Upper Reach of Yangtze River Basin, China

Based on remote sensing(RS) and geographic information systems(GIS) technology,land use change in the upper reach of Yangtze River basin from 2000 to 2006 was analyzed.Export coefficient model was used to estimate the pollution loads of diffuse source caused by land use.Diversity and effect of diffuse source pollution load caused by land use change were obtained,from total nitrogen(TN)and total phosphorus(TP) loads of diffuse source,load intensity and the different sources of the TN and TP caused by land use in the upper Yangtze River basin.In the upper reach of Yangtze River basin,arable land area decreased to 1.10×104 km2,forest area increased to 1.10× 104 km2,grassland and other land use areas changed little from 2000 to 2006.With ecological projects of natural forest resources protection,Yangtze River protective forest,return farmland to forest,the ecological environment had been improved,since the development of the western region of China.The diffuse source TN and TP were 114.14×104 t and 3.39×104 t in 2000,111.21×104 t and 3.31×104 t in 2006 respectively in the upper reach of Yangtze River basin.Diffuse source TN and TP load decreased significantly in Yalong River basin,the upper reaches of the Dadu River,upper reaches of Minjiang River in northwestern Sichuan Province and Wujiang River in northern Guizhou Province from 2000 to 2006.