不同空间尺度景观特征对南流江水质的影响差异

流域景观特征决定了非点源污染物来源与地表景观削减消纳能力，但尚缺乏全流域不同空间尺度对二者关联性的认识。以广西北部湾南流江为例，分别在子流域、河岸缓冲带以及监测点圆形缓冲区三种尺度上，基于2020年Landsat 8 OLI遥感影像解译的土地利用类型特征，结合水质监测数据，运用数理统计和GIS空间分析方法，探讨了流域景观特征在不同空间尺度上对河流水质的影响。结果表明：(1)在子流域尺度，土地利用类型以林地为主，而在河岸缓冲带与监测点圆形缓冲区均以耕地为主；(2)水质指标高锰酸盐指数、生化需氧量与景观特征相关性最为显著，耕地、建设用地、其他用地和园地与其呈正相关，是南流江水质污染负荷的重要来源区；景观格局指数中，斑块密度、蔓延度指数、多样性指数、均匀度指数是引起河流水质指标变化的主要景观因子；(3)受流域内或不同子流域间景观特征差异，景观组成面积占比和景观格局指数均在河岸缓冲带尺度对水质状况影响最大，分别可解释57.0%和64.7%的水质指标变化；子流域尺度次之，圆形缓冲区尺度最小，且景观格局指数对水质状况的影响大于景观组成面积占比。建议在河岸带50 m范围内严格控制耕地面积，建设河岸缓...

Differences in the influence of landscape features on river water quality at different spatial scales

Watershed landscape characteristics determine the sources of pollutants and the absorption potential of the surface landscape, but we still lack the knowledge of their relation from different spatial scales in the whole watershed. Based on the land use type interpreted by Landsat 8 OLI remote sensing image in 2020 and combined with the water quality index data of monitoring points, the influence of landscape characteristics on river water quality at different spatial scales including sub-watershed, river buffer zone and circular buffer zone of monitoring points was discussed using mathematical statistics and GIS spatial analysis method. The results show that:(1) the landscape composition is different at different spatial scales. At sub-watershed scale, forest land is the main land use type. At river buffer zone and circular buffer zone, cultivated land are the main land use type. (2) The cultivated land, construction land, other land and garden land are positively correlated with water quality index COD_Mn, BOD₅, which are the contribution sources of water quality pollution in the Nanliu River Basin. The increase of grassland, forest land and water area is generally beneficial to the improvement of river water quality, especially at the scale of river buffer zone. PD, CONTAG, SHDI and SHEI are the main factors causing river water quality change. (3) Landscape characteristics of river buffer zone had the greatest impact on water quality, followed by sub-watershed scale and circular buffer scale according the total explanation rate of redundancy analysis. To economically protect water quality in the Nanliu River, we should focus on riparian zone within 50 m and decrease the cultivated land area and optimize its landscape structure.