潭江流域水质时空分布特征及其与土地利用的相关性分析

以潭江流域为研究区域,利用2016年5月TM遥感影像底图,结合Google高清影像和实地调查修正获取流域土地利用图。运用ArcGIS分析工具,将流域分为26个子流域,研究各子流域的土地利用结构。根据2015~2016年不同水期的水质监测,分析TP、TN、NH_4~+-N、高锰酸盐、COD的时空分布特征;利用spearman相关与逐步多元回归分析其与土地利用结构的相关性。结果表明,各项水质指标基本表现为丰水期优于平水期,枯水期最次。在空间上,上游水质优于中游水质,下游水质最次。流域土地利用结构与水质之间的关系表现为:林地、草地能够缓解水质恶化,相当于"汇",耕地、建设用地、水体会导致水质恶化,相当于"源"。建设用地是对水质恶化影响最大的因素,其次是耕地。部分流域污水处理率有限及污水处理的水质标准与地表水水质标准的差距较大,可能是水质难以好转的主要原因。林地能够显著改善水质,应该加强管理和保护。

Spatiotemporal Distribution of Water Quality in the Tanjiang River and Its Correlation with the Land Use

The Tanjiang river basin was studied on the basis of Landsat TM orthophoto images (May 2016), HD images from Google, and field survey data. The Tanjiang river basin was divided into 26 sub-watersheds according to ArcGIS analyses, and the land use of each sub-watershed was connected with 5 parameters of water quality, including TP, TN, NH₄⁺-N, permanganate index and COD, which were collected during years of 2015-2106, using Spearman correlation and stepwise multiple regression to analyze the correlation between land use and spatiotemporal distribution of water quality in the Tanjiang river. The results showed that all 5 parameters of water quality were best in the wet season, worst in the dry season, best in the upstream and worst in the low-stream. The forestland and grassland can alleviate the water quality deterioration, such can be called as the "sink" of water deterioration, while the cultivated land and building site can exacerbate the water quality deterioration, such can be called "source" of water deterioration. The building site had the most prominently negative impact on water quality, followed by the cultivated land. The limited treatment rate of waster water and low treatment level of sewage in certain watersheds might be the major impediment for improving the water quality. We suggested that the forestland, which can improve the water quality prominently, deserves more management and protection.