不同雨强条件下河流水质对流域土地利用类型与格局空间响应

以七乡河流域为研究区域,基于2015年4、5、6月3次不同雨强条件下的河流水质实时监测数据,以及区域DEM数据和遥感数据,根据高程与坡度将流域划分5级河流缓冲区,研究不同雨强条件下各缓冲区内土地利用类型、格局与河流水质之间的响应关系.结果表明:1不同空间单元土地利用类型与格局存在差异.低缓区域、中缓区域和高缓区域优势土地利用类型为建设用地;中陡区域和高陡区域林地为优势土地利用类型.2低缓区域是不同雨强条件下,土地利用类型对河流水质影响最大的空间单元.3低缓区域建设用地对水质的影响最大;中缓区域湿地对小雨强时水质影响最大;建设用地对中等雨强和大雨强时水质影响最大.中陡和高缓冲区,建设用地对小雨强时水质影响最大;而中等雨强和大雨强时林地对水质影响最大.4土地利用格局对河流水质影响比较复杂.平均斑块形状指数对低缓区域水质影响最大;斑块密度、平均斑块形状、多样性指数分别是中缓区域3种雨强时对水质影响最大的格局因子;高缓区域3种雨强条件下平均斑块形状指数、多样性指数和斑块密度对水质影响最大;平均斑块形状指数和蔓延度是中陡区域和高陡区域小雨强和大雨强时对水质影响最大,蔓延度和多样性指数是中等雨强时影响最大土地利用格局因子.

Spatial Response of River Water Quality to Watershed Land Use Type and Pattern Under Different Rainfall Intensities

Qixiang River watershed, as a typical case study area, was divided into five types of buffer zones according to elevation and slope. Based on the remote sensing images, DEM and real-time monitoring data in April, May, June 2015, the relationship between land use type and pattern in all buffer zones and water quality under different rainfall intensities was explored. The results showed that land use type and pattern in different buffer zones had obvious discrepancies. The proportion of construction land was the highest in low flat area, secondary flat area and high flat area. The main land use type of moderately steep area and high steep area was forest land. Secondly, the low flat area appeared to have the greatest influence on the water quality. Thirdly, construction land had a greater influence on water quality than other land use types in low flat area. In addition, in secondary flat area, wetland was the key factor under small rainfall intensity. However, construction land was the key factor under moderate rainfall intensity and large rainfall intensity. In moderately steep area and high buffer zones, construction land influenced the water quality most under small rainfall intensity but forest land was the greatest factor under moderate rainfall intensity and large rainfall intensity. Fourthly, the relationship between the land use pattern and water quality was complicated. SH-MN had the greatest influence on water quality and the influence increased with increasing rainfall intensity in low flat area. Furthermore, PD, SH-MN and SHDI were the key factors in secondary flat area while SH-MN, SHDI and PD were the key factors in high flat area under all the three types of rainfall intensity. SH-MN and CONTAG influenced the water quality most in moderately steep area and high steep area under small and high rainfall intensity. CONTAG influenced the water quality most in moderately steep area and SHDI was the key factor in high steep area under moderate rainfall intensity.