筑坝河流不同尺度土地利用结构对库区水质的影响——以平寨水库为例

Effects of multi-scale land use structure on water quality of Damming Rivers——a case study of Pingzhai Reservoir

为了分析筑坝河流域人类活动与库区水质的响应关系,以平寨水库为例,选取子流域、河流缓冲区及监测点圆形缓冲区三种尺度,基于2017年Landsat8 OLI遥感影像解译结果所反映的土地利用结构特征,结合实测监测点水质指标数据,运用GIS空间分析及统计分析的方法,探讨筑坝河流流域土地利用结构对库区水质的影响。结果表明:(1)在三种尺度上,土地利用结构与库区水质都有显著相关性,河流缓冲区和子流域尺度相关规律基本一致,但与圆形缓冲区尺度相关规律差异较大;(2)不同土地利用类型面积比例对水质的影响存在尺度效应,不同尺度上表现出不同的"源"与"汇";(3)土地利用相对合理指数R与水质指标呈显著负相关,说明土地利用结构越合理,越有利于减少土壤侵蚀,水体中污染物浓度就越低。

The relations between land use structure and reservoir water quality in damming river basin are discussed on the sub-basin scale and stream buffer zone and circular buffer scale of monitoring point. Pingzhai reservoir is chosen as the study area because of its representativeness. The GIS spatial analysis and statistical analysis were employed based on the water quality monitoring data and Landsat8 OLI data in 2017.The result shows that Land use structure and reservoir water quality had significant correlation at multi-scale. The correlation rules of stream buffer and sub-basin scale are basically the same, but they are different from those of circular buffer scale. The influence of different land use types on water quality varies among scales and shows different sources and sinks. There is a significant negative correlation between R and water quality index. Therefore, the more reasonable the land use structure is, the more beneficial it is to reduce soil erosion and the lower the pollutant concentration is in water.