基于流域尺度的农业用地景观-水质关联分析

基于Landsat遥感影像进行九龙江流域不同坡度类型的农业用地景观与水质指标（CODMn、NH4+-N、TP）的相关性分析，并分别对丰水期、枯水期、平水期的农业用地类型百分比与各水质指标进行线性回归。结果显示，坡度小于15°和大于25°的农业用地占总农业用地的面积比例与各水质指标呈较强的正相关。景观聚集度指数（CONTAG）与水体中TP浓度呈显著正相关，决定系数为0.565；香农多样性指数（SHDI）与水体中TP浓度呈显著负相关，相关系数为-0.527。丰水期和枯水期是九龙江流域水质变化较大的时期。对河流近岸100 m范围内的农业用地类型组成进行统计发现，坡度小于15°的农业用地面积平均比例为74.3%。河岸缓冲区和陡坡农业用地的数量及分布是影响该地区水质及控制农业非点源污染的关键。

Analysis on linkage between farm landscape and water quality in Jiulong River watershed

Correlation analysis was performed to explore the relationships between CODMn, NH4+-N, TP and farm landscape in the Jiulong River watershed. Linear regressions between water quality and farm land percents were also processed in flood season, dry season and average season. The results showed that the total proportion of farm lands located in the slopes less than 15 degrees and greater than 25 degrees were positively correlated with CODMn, NH4+-N and TP concentrations in the water. Contagion index (CONTAG) of farm lands was positively correlated with TP concentrations, and Shannon Diversity Index (SHDI) of farm lands was negatively correlated with TP concentrations. The determinate coefficients were 0.565 and -0.527, respectively. Water eutrophication was susceptible to farm land pollutions in flood season and dry season. The farm lands located in the slopes less than 15 degrees took up 74.3% in the 100m-width riparian buffer. The farm lands located in the riparian buffer and in the deep slopes played a crucial role in water quality management, especially the non-point source pollution control in the Jiulong River watershed.