Integrated Spatial Characteristics of Land Use Influencing Water Quality in Upper Catchment of Miyun Reservoir

Land use closely relates to water nutrient concentrations, previous studies majorly concern the quantitative structure of land use, and lacks a comprehensive consideration for the spatial information of land use. Taking the upper catchment of Miyun Reservoir as the study area, based on the eco-hydrological processes affecting the export, migration and transformation of water pollution, this study systematically analyzed the impact of land use on water nutrient concentrations. It portrayed and explored the land use information influencing water nutrient, which includes land use intensity, slope of land use, distance of land uses to the river and monitoring sites, and spatial arrangement of land uses. This study coupled above four aspects of information to construct multiple linear regression models between land use and total nitrogen, total phosphorus and COD concentration. Without considering the above four aspects of land use information, the coefficients of determination of three multiple linear regression models are 0.294, 0.471 and 0.223, respectively. Taking above information into consideration, coefficients of determination of three multiple linear regression models are 0.532，0.685 and 0.489, respectively. After quantifying the contribution of land use on nutrient concentrations of monitoring sections in each spatial location, this study compared the mean cumulative contribution rates of land use to nutrient concentrations and the corresponding cumulative area percentage at different distances to river. Finally, it suggested that the distance to the river in 1 kilometer range would be the key area to control water eutrophication in the upper catchment of Miyun Reservoir.