沣河流域土地利用格局与水质变化的关系

Relationship Between Changes of Land Use Pattern and Water Quality in Fenghe River Basin

以沣河流域为研究对象,综合运用遥感影像解译和相关分析方法分析了沣河流域的土地利用空间格局及主要水质指标〔生化需氧量(BOD5)、高锰酸盐指数(CODMn)、氨氮(NH3—N)含量及溶解氧(DO)〕含量的变化特征,探讨了土地利用状况对沣河水质的影响。结果表明,沣河流域土地利用类型以林地和耕地为主,两者占全流域面积的90%以上;沿河不同宽度的缓冲区(分别向两岸划分100,600,1 500m)范围内,建设用地、耕地与水质变化呈正相关关系,而林地与水质变化呈负相关关系,表明建设用地及耕地对水质的改善有负效应,而河流沿岸林对改善水质有正效应,并且这种影响在距河岸100m缓冲区范围内达到最大。随着缓冲距离的增大土地利用变化对水质的影响逐渐减弱,说明沣河流域近岸带的土地利用方式对河道水环境质量的影响最大。

Land use/land cover of Fenghe River Basin was quantitative analyzed using Landsat TM image which acquiring in 2009, and its effects on water quality were evaluated by Pearson correlation analysis, in which, the main water quality indexes included BOD5, CODMn, NH3--N and DO. The results showed that the forest and cultivated lands were the main land use types, and they accounts for more than 90% of the whole basin area. The buffer area which along the main tributary extending 100, 600 and 1 500 m, the culti- vated land and constructive land were positively correlated with water quality index, while forest land were negatively correlated with water quality index. It indicated that the land use in the river basin had great impacts on water quality parameters, construction land and cultivated land have negative effects on water quality, and forest land has positive effects on water quality. The influence of land use to water quality achieved the maximum in 100 m buffer area. With the increase of the buffer distance, the influence was weaken gradually. It indicated that land use is the main factor influencing water environmental quality in Fenghe River Basin.