新安江流域土地利用结构对水质的影响

以新安江上游流域为研究区域,用该流域2010年5月TM遥感影像图作为底图,通过实地野外调查获取了新安江流域的土地利用图.运用ArcGIS的水文、空间分析功能,将流域划分为8个子流域,并分析各子流域的土地利用结构.根据2010年1～12月的水质监测数据,分析TN、TP、高锰酸盐指数、NH4+-N、粪大肠菌群的时空变化特征,以及与土地利用结构之间的定量关系.结果表明,TN和NH4+-N有明显的时间变化特征,为枯时期>丰水期>平水期,而其他几种指标没有明显的时间变化.在空间上,整体上呈现出渔梁、浦口污染最为严重.流域内土地利用结构与水质之间的相关关系表现为:耕地、水体、建筑用地起源作用,林地、草地起汇作用.在年度上看,耕地对TN、NH4+-N、高锰酸盐指数影响最大,草地对TP影响最大;不同水期上,枯水期和丰水期,对各指标影响最大的土地利用类型为耕地,在平水期,对TN、TP、粪大肠菌群影响最大的土地利用类型分别为耕地、草地、林地.

Effects of Land Use Structure on Water Quality in Xin'anjiang River

Take Xin'anjiang upstream watershed as a case study. Based on data of interpreting TM orthophoto images and water quality monitoring in May 2010, the land use map of Xin'anjiang River, which was categorized to cultivated land, forestland, grassland, water body, building site, was obtained. Using ArcGIS hydrological and spatial analysis function, Xin'anjiang River was divided into eight sub-watersheds, and its watershed land use structure was analyzed. The water quality parameters such as TN, TP, permanganate index, fecal coliform bacteria were monitored from Jan 2010 to Dec 2010. The relations between water quality and land use were analyzed. The results showed that TN and NH₄⁺-N had a significant temporal variation: dry season>wet season>normal river flow period, but other parameters did not vary significantly. In the space, Yuliang and Pukou were the most serious pollution sites. Cultivated land, water body, building site had a positive impact on water quality parameters, while there were negative correlation between the forestland and grassland. Annually, cultivated land had the most significantly important effect on TN, NH₄⁺-N and permanganate index, and grassland had the most significantly important effect on TP. Cultivated land had the most prominently important impact on water quality parameters in dry season and wet season. What's more, in the normal river flow, cultivated land, grassland and forestland had the most remarkably important influence on TN, TP and fecal coliform bacteria respectively.