入湖河流水质对土地利用时空格局的响应研究:以洱海北部流域为例

Response of Inflow Water Quality to Land Use Pattern in Northern Watershed of Lake Erhai

揭示土地利用与入湖河流水质的内在联系是非点源研究的重要内容,以洱海北部流域为研究对象,从土地利用类型组成和空间格局入手,综合空间分析和统计分析方法对两者响应关系进行研究.结果表明,研究区平均坡度(SLOPE)、植被区面积百分比(VEG)作为表征土地利用类型组成的指标,与入湖河流TN和TP的关系显著,斑块密度(PD)、农业用地斑块密度(PDagr)、水体形状指数(LSIwat)作为表征土地利用空间格局的指标,与TP和NH+4-N的关系显著;类型水平下,入湖河流水质对土地利用空间格局的响应关系较景观水平强,水质响应指标为雨季TP和旱季NH+4-N,回归调整系数R2分别为0.761和0.978;旱季,入湖河流水质对土地利用的响应关系强于雨季,水质响应指标为TN、TP和NH+4-N.因此,进行洱海北部流域非点源污染治理时可考虑提高植被覆盖率和农业用地集约化程度,尽量避免旱季对自然水体的人为干扰,后续进行土地利用空间格局与入湖河流水质关系研究建议选类型水平.

The inherent relationship between land use pattern and inflow water quality is essential for nonpoint source pollution study.Response of inflow river quality to land use pattern in Northern part of Lake Erhai Watershed was analyzed in aspects of land use composition and configuration using spatial analysis and statistical analysis methods. The results indicated that as land use composition indexes,average slope and vegetation area percentage had significant relationship with TN and TP of inflow rivers. As land use configuration indexes,patch density,patch density of agriculture land and landscape shape index of water had significant relationship with TP and NH＋4-N of inflow rivers. Response of inflow river quality to land use pattern was better at class level than at landscape level. Water quality response indicators were TP in rainy season and NH＋4-N in dry season,of which regression adjustment coefficient R2 was 0. 761 and 0. 978,respectively. Response of inflow river quality to land use pattern was better in dry season than in rainy season,and the water quality response indicators were TN,TP and NH＋4-N. Improving vegetation coverage and agriculture land intensive degree and avoiding human disturb to natural water area especially in dry season were suggested in nonpoint source pollution control of northern watershed of Lake Erhai Watershed. Later research on relationship between land use configuration and inflow river quality should better be at class level.