西江下游流域水质与不同空间尺度土地利用的响应关系

基于西江下游流域2005—2017年11个监测断面水质数据和2005年、2010年、2018年遥感影像数据，通过不同空间尺度和土地利用类型的划分，利用Spearman秩相关系数法、冗余分析等方法分析了不同空间尺度下土地利用结构对西江下游流域水质的影响。结果表明:2005—2017年西江干流、贺江及罗定江水质较为优良，新兴江、南山河水质恶化明显，西江干流汛期总磷浓度明显高于非汛期；流域尺度下，河流水质指标与城镇用地呈显著正相关关系，与水体呈显著负相关关系；河岸缓冲区尺度下，河流水质指标与林地、水体呈负相关关系，城镇用地对河流中COD解释度较高，800 m缓冲区城镇用地对氨氮和总磷解释度最高，河流水质指标与旱地相关性在缓冲区达到 1 500 m后显著上升，800 m缓冲区内水田坑塘对河流水质指标影响较大。建议对西江下游流域河岸800 m宽度范围内城镇用地、水田坑塘以及1 500 m缓冲区外旱地加强污染管控。

Response relationship between water quality in the lower reaches of Xijiang River Basin and land use at different spatial scales

Based on the water quality data of eleven monitoring sections in the lower reaches of Xijiang River Basin from 2005 to 2017 and remote sensing data in 2005, 2010 and 2018, the influence of land use structure at different spatial scales on the water quality in the lower reaches of Xijiang River Basin was analyzed by methods such as Spearman rank correlation coefficient method and redundancy analysis through different spatial scales and division of land-use types. The results show that from 2005 to 2017, the water quality of the main stream of Xijiang River, Hejiang and Luoding River was good in general, while water quality of Xinxing River and Nanshan River deteriorated significantly. Meanwhile, TP concentration in the main stream of Xijiang River in the flood season was obviously higher than that in the non-flood season. At the scale of river basin, the river water quality index was significantly positively correlated with construction land while significantly negatively correlated with water body. At the scale of river bank buffer zone, the river water quality index was negatively correlated with forest and water body. The interpretation of construction land to COD was relatively high, and the interpretation of construction land in 800 m buffer zone to TP and NH₃-N was the highest. The correlation of river water quality index and dry land rose significantly when buffer zone reached 1 500 m, and the impact of paddy field in 800 m buffer zone on river water quality index was great. It is suggested to strengthen pollution control measures for construction land, paddy field within 800 m and dry land outside 1 500 m buffer zone.