基于GIS的红枫湖流域土地利用变化与水质响应

为探究红枫湖流域土地利用变化与水质的响应,利用ENVI 5.2、Arc GIS 10.2软件对红枫湖流域2001、2008年和2016年的Landsat TM影像进行解译,选取监督分类法结合人工修正将研究区分为水域、林地、耕地、草地、建设用地、未利用地6个土地类型,并与水质进行Spearman秩相关分析。研究表明,红枫湖流域以林地和耕地为主,占总面积的60%以上。从2001年到2016年,耕地、林地、未利用地均有所减少,主要流入建设用地和草地,林地面积减少了10.68 km2,减幅达7.30%,建设用地增加了11.41 km~2,增幅达36.11%。2001年水质总体为Ⅲ类,建设用地与TP、NH3-N、COD呈现明显正相关关系,表明污染主要来自于工业源和生活源;2008年建设用地、耕地与营养指标表现出正相关关系,但未达到显著水平,水质总体为Ⅳ类,水质较差可能是工业源、农业源和生活污染源共同作用的结果;2016年耕地与TP、NH3-N、COD和DO的相关系数分别达0.757*、0.750、0.786*和-0.847*,说明在工业污染源和生活污染源得到治理后,农业面源成为红枫湖流域的主要污染源,但其排放系数较小,水质为Ⅱ类,没有对水质产生较大影响。总体上建设用地和耕地表现为污染"源"的作用,林地则呈现"汇"的效应。

Response relationship between land-use change and water quality in Hongfeng Lake basin based on GIS

In order to understand the relationship between land-use change and water quality in the Hongfeng Lake basin, Landsat TM images from 2001, 2008, and 2016 were interpreted using ENVI 5.2 and ArcGIS 10.2. This paper divides the research area into the following:Water, woodland, farmland, grassland, construction land, and unused land. This is done using supervised classification and artificial correction, and the Spearman correlation analysis to evaluate water quality. The results indicate that Hongfeng Lake basin is dominated by woodland and farmland, accounting for more than 60% of the total area. The farmland, woodland and unused land have, over the last 15 years, been converted to construction land and grassland. The decreasing area of the woodland is 10.68 km², or 7.30%, but the increasing area of the construction land is 11.41 km², or 36.11%. The data show that there is an evident positive correlation between the area of the construction land in 2001 and nutrition indexes such as TP, NH₃-N and COD, indicating that the pollutants mainly came from industrial and domestic activities before environmental treatment was carried out. In 2008, the nutrition indexes show a positive correlation with the farmland and the construction land, not reaching a significant level, so the point and non-point source might be resultant of poor water quality. In 2016, the correlation coefficients of the farmland with TP, NH₃-N, COD and DO are 0.757^*, 0.750, 0.786^* and 0.847^* respectively, which indicates that agricultural non-point source pollution is the dominant contributor to Hongfeng Lake basin after controlling industrial and domestic pollution, however there is a relatively small emission coefficient and water quality is only slightly impacted. Conclusively, the construction land and farmland are regarded as "sources", and the woodlands as "sinks".