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

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 NH₄⁺-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 NH₄⁺-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 NH₄⁺-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.