不同空间尺度河流水质与土地利用关系分析——以泰国蒙河流域为例

Relationship between water quality and land use at different spatial scales:A case study of the Mun River basin,Thailand

为分析不同空间尺度河流水质与土地利用的响应关系,认识水环境变化成因和趋势,以泰国蒙河流域为研究对象,采用GIS、莫兰指数(Moran′s I)和Spearman相关分析等方法,探究蒙河水质的空间分异及不同空间尺度下水质对土地利用格局的响应特征。结果显示,近20 a(1997—2017年)流域内溶解氧(DO)、生化需氧量(BOD)、总磷(TP)、硝态氮(NO3--N)、氨氮(NH3-N)、固体悬浮物(SS)的Moran′s I值分别为0.86、0.38、0.35、0.40、0.45、0.50,表现出空间聚集性,而总大肠菌群(TCB)、粪大肠菌群(FCB)的Moran′s I值分别为-0.15、-0.10,具有空间离散特征。不同空间尺度下河流水质与土地利用的相关性大体一致,但相关程度存在差异,缓冲区尺度的土地利用格局能够更好地解释蒙河水质变化,其中水质指标与5 km缓冲区空间尺度下土地利用的关系最为显著。相关分析结果表明,蒙河流域农业用地、城镇建设用地对水质负荷起到"源"的作用,林地起到截留、吸附的作用。因此,蒙河流域水环境保护应以非点源污染控制为主,重点加强农业生产过程中化肥等管控,控制生活污水等污染物直排入河。

Analyzing the relationship between land use and water quality at different spatial scales is of great value for understanding the causes and trends of water environment changes and promoting restoration and protection of the basin ecosystem.Taking the Mun River basin in Thailand as the research object,GIS,Moran′s I,and Spearman correlation analysis were used to explore the spatial distribution and differences in water quality and the response of water quality to land use patterns at different spatial scales.The results showed that in the past 20 years(1977—2017),the Moran′s I values of dissolved oxygen,biochemical oxygen demand,total phosphorus,nitrate nitrogen,ammonia nitrogen and suspended solids were 0.86,0.38,0.35,0.40,0.45,and 0.50,respectively,thereby showing significant spatial aggregation in the basin.Meanwhile,the Moran′s I values of total coliform bacteria and fecal coliform bacteria were-0.15 and-0.10,respectively,thereby showing discrete spatial patterns.The relationship between river water quality and land use is generally consistent at different spatial scales,but discrepancy exists in the relevance.The land use pattern at the buffer zone scale can better explain the water quality change in the Mun River basin;the relationship between water quality indicators and land use at the 5 km buffer scale is more significant.The relevant analysis results show that agricultural land and urban construction land act as a source of the water quality pollution load,while forest land intercepts and absorbs pollutants.Therefore,the water environmental protection in the Mun River basin should be based on non-point source pollution control,and focus on strengthening the control of fertilizers in agricultural production processes and controlling the direct discharge of pollutants such as domestic sewage into the river.