土地利用结构对非点源污染的影响

Effects of land use structure on non-point source pollution.

当点源污染得到有效的监控时，非点源污染（Ｎｏｎ－ｐｏｉｎｔ ｓｏｕｒｃｅ ｐｏｌｌｕｔｉｏｎ），尤其是农业非点源污染将成为影响地表水水质的主要因素．在野外布点采样及分析的基础上，利用地理信息系统（ＧＩＳ）研究了蓟运河卜游于桥水库流域内不同土地利用结构与地表水水质的相关关系．结果表明，在以单一上地利用类型为主控制的流域中，林地和草地控制的小流域的地表水水质明显好于以耕地为上的小流域；在不同土地利用类型（林地、草地和耕地等）的组合结构中，各项污染物浓度往往介于林地、草地或耕地为主控制的小流域之间；在其他条件相似时，随着小流域内林地和草地的增加，非点源污染降低，而随着耕地比例的升高，非点源污染有逐渐增大的趋势。

As point source pollution has been effectively controlled, non--Point source pollution, especially that of agricultural, will become the main factor affecting the surface water quality. On the bases of field sampling and analysis,using the GIS techniques, this paper investigates the relationship between. the land use structure and the surface water quality of the Ji canal upstream of Yuqiao Reservoir catchment .The results show: (1) In the watersheds which are controlled mainly by a single land use type, the surface water quality of woodland and grassland-controlled watersheds is distinctly better than that of watersheds controlled by farmland. (2) In the combined structure of different land use types (woodland, grassland and farmland), the concentration of pollutants is in the middle of the watersheds which are controlled primarily by woodland or grassland and those controlled by farmland. (3) When other conditions are similar, the concentration of non-point source pollution decreases according to the increase of the area of woodland and grassland, while increases with the increase of the area of farmland in the watersheds.