太湖上游水源区河流水质对景观格局变化的响应关系——以东苕溪上游为例   总被引：2，自引：0，他引：2  

范雅双  于婉晴  张婧  李雪  李小玉 《湖泊科学》2021,33(5):1478-1489

景观格局演变作为人类活动的综合表征,通过改变水文过程和径流路径,从而影响非点源污染物的发生位置、迁移路径和转化过程,进而对流域水环境产生深刻影响.苕溪作为太湖的主要入湖河流之一,对太湖水环境有着关键的影响作用.本文以发源于杭州市临安区太湖源镇的东苕溪上游区域作为研究对象,在对河流水质进行两个时期监测的基础上,运用相关性分析、冗余分析和逐步回归分析等方法,综合景观组分指数和景观空间配置指数,在子流域尺度上量化景观指数对河流不同水质指标的解释能力,探讨河流水质对流域景观格局的响应规律.结果表明:1)东苕溪上游大部分监测点总氮浓度远超地表水V类水质标准限值,但氨氮和总磷浓度整体较低,部分监测点可达Ⅰ类水质标准.2)在汛期,景观组成中流域的"源"景观比例是影响水质的重要因素,农业用地占比与硝态氮、总氮浓度呈显著正相关,建设用地占比对氨氮、总磷浓度影响显著;而在非汛期,景观配置因子,特别是表征斑块形状的周长—面积分形维数(PAFRAC)对河流水质的影响极显著.3)无论是汛期还是非汛期,林地和草地对河流中污染物均具有显著的削减作用,是流域河流污染防治的关键"汇"景观.4)从整体上来看,河流氮、磷污染与人类活动强度密切相关,增加景观连通性、降低自然景观的破碎化程度可有效改善河流水环境.  相似文献   

Geographic information system–based morphometric characterization of sub-watersheds of Meenachil river basin,Kottayam district,Kerala, India     

M.V. Vincy  Brilliant Rajan  A.P. Pradeepkumar 《国际地球制图》2013,28(8):661-684

The study areas Tikovil and Payppara sub-watersheds of Meenachil river cover 158.9 and 111.9 km², respectively. These watersheds are parts of Western Ghats, which is an ecologically sensitive region. The drainage network of the sub-watersheds was delineated using SOI topographical maps on 1:50,000 scale using the Arc GIS software. The stream orders were calculated using the method proposed by Strahler's (1964 Strahler, A. N. 1964. “Quantitative geomorphology of drainage basins and channel networks”. In Hand book of applied hydrology. Vol. 4, Edited by: Chow, V. T. Vol. 4, 39–44.  [Google Scholar]). The drainage network shows that the terrain exhibits dendritic to sub-dendritic drainage pattern. Stream order ranges from the fifth to the sixth order. Drainage density varies between 1.69 and 2.62 km/km². The drainage texture of the drainage basins are 2.3 km^–1 and 6.98 km^–1 and categorized as coarse to very fine texture. Stream frequency is low in the case of Payappara sub-watershed (1.78 km^–2). Payappara sub-watershed has the highest constant of channel maintenance value of 0.59 indicating much fewer structural disturbances and fewer runoff conditions. The form factor value varies in between 0.42 and 0.55 suggesting elongated shape formed for Payappara sub-watershed and a rather more circular shape for Tikovil sub-watershed. The mean bifurcation ratio (3.5) indicates that both the sub-watersheds are within the natural stream system. Hence from the study it can be concluded that GIS techniques prove to be a competent tool in morphometric analysis.  相似文献