景观背景对丹江口库区典型小流域水质的影响

[Objective] Soil erosion and non-point source pollution have become increasingly prominent in the Danjiangkou Reservoir area, affecting the water quality of inflow rivers and posing a threat to the water security of the Danjiangkou Reservoir area. Existing studies have not thoroughly analyzed the influence of landscape patterns at different scales on water quality. This study aims to supplement research on the differentiated effects of landscape pattern indices at different scales on water quality in the Danjiangkou Reservoir area, thereby providing a reference for developing scientifically sound water quality protection and improvement measures. [Methods] We took the Shibanhe small watershed in the Danjiangkou Reservoir area as the research object. Based on the spatial pattern characteristics of land use, we adopted spatial analysis, mathematical statistics and Mantel test to reveal the spatial differentiation characteristics of different water quality indicators, investigate the main landscape pattern indices affecting water quality at scales such as subwatershed, river buffer zone, and circular buffer zone, and explore the mechanisms of landscape background on surface water quality. [Results] (1) The concentrations of total nitrogen (TN) and nitrate nitrogen () in the surface water of the Shibanhe small watershed were relatively high, mainly distributed in the central and southeastern parts of the watershed where cultivated land and residential areas were concentrated. Orchards near the river also served as important potential sources of river water pollution. (2) At different scales, the proportions of cultivated land and forest land had a significant impact on river water quality, and their correlation was more significant at scales of subwatershed, 100 m river buffer zone, and 200 m river buffer zone. At the subwatershed scale, patch density (PD) had a highly significant correlation with TN and . Landscape pattern indices, such as contagion index (CONTAG), cohesion index (COHESION), Shannon’s diversity index (SHDI), and Shannon’s evenness index (SHEI), had certain effects on water quality at all scales, and their effects were greater at subwatershed and 100 m rive buffer zone scales. (3) The effects of landscape background on river water quality had a significant scale effect. The subwatershed and 100 m river buffer zone scales were the key scales affecting river water quality, where landscape structure and landscape pattern exerted the greatest influence. [Conclusion] Management and regulation of landscape structure and landscape patterns at scales of subwatershed and 100 m river buffer zone—especially strengthening the monitoring and management of landscape fragmentation—are of great significance for improving river water quality in the Danjiangkou Reservoir area. Future research should strengthen long-term water quality monitoring to reveal dynamic change patterns of regional water quality and seasonal differences in their driving factors.