不同土地利用类型对城市湿地水质的影响--以南京市紫金山山间小流域湿地为例

Influence of Land Use on Water Quality in Urban Area——A Case Study of Zijin Mountain in Nanjing

综合运用RS和GIS技术对南京市紫金山周边小流域进行边界提取、土地利用类型分析,并且通过水样野外采集与实验室分析处理方法自2008年3月至2009年2月一年间对小流域所在水库水质进行监测.通过计算水质指数(WQI)得出其季节性变化规律,结合该小流域土地利用类型特征,揭示流域内土地利用类型与水质之间的关系.结果表明:各小流域内土地利用类型对下游水体水质影响显著.①水质指数(WQI)季节性变化主要表现在:上游有建设用地的小流域从春季到秋季期间WQI有降低趋势,从秋季到冬季又逐渐上升;而无建设用地或者建设用地面积比例较小的小流域在夏季暴雨径流的影响下,水质会逐渐改善,WQI有升高趋势.②小流域内建设用地对各小流域水体水质有负效影响.而以景观林为主的苗圃对下游水体影响不大;流域内林地、水库占流域面积越大,其下游水体水质则相对较好,对水质改善有着正效影响.

This study extracts the boundary of the small catchments, and analyzes of land use type of these small catch- ments around the Zijin Mountain in Nanjing with the aid of remote sensing, GIS techniques. Water quality was monitored from March 2008 to February 2009 by the methods of water quality collection and analyzes in the laboratory. Statistical analysis and the seasonal variation of the water quality indices （WQI） are used to illustrate the relationship between land use type and the water quality in the study area. Results show that the typical of the land use of the small catchments af- fect the water quality down streams obviously. （1） The seasonal variation of the WQI show that all of the WQI declined from spring to autumn and it would be increased from autumn to winter except Wuming reservoir. It is because rainstorm carried lots of pollutant from the construction land to the downstream water body during summer. （2） Water quality would get worse when the usage of construction land got bigger and the water quality would get better when the forest land and reservoir land got bigger. So it could be concluded that the usage of construction land would obviously result in the water pollution while the usage of forests land and land would keep it down.