Diagnosis of eco-environment quality in Wujiang River watershed based on RS and GIS

The Wujiang river watershed lies on the Yunnan-Guizhou plateau slope, is the largest branch of the south bank of the upper Yangtze River, has unique geology and geomorphology and widely developed karst landform. Owing to long-term irrational exploitation and utilization on a large scale, the river watershed is confronted with serious soil and water loss and outstanding desertification problems. By using the TM images of the Wujiang river watershed in 2010 as the main information source, the paper, takes 41 regions (cities, counties and districts) in the Wujiang river watershed (in Guizhou province) as study area, extracts land use information and landscape pattern indexes based on RS and GIS, constructs the evaluation index system of the ecological quality in the Wujiang river watershed, determines the index weight by entropy method, combines with GIS graphic overlay method, evaluates the ecological environment quality situation of the 41 regions. Based on the above works, the ecological quality in the Wujiang river watershed divided into four levels: good（Ⅰ）, relatively good（Ⅱ）, general（Ⅲ） and poor （Ⅳ）. The research result shows that the area of good, relatively good, general and poor ecological environment quality in the Wujiang river watershed in 2010 year is 7 710.8 km2, 26 208.3 km2 15 704.3 km2 and 16 106.1 km2 respectively, and the weight is 11.7 %, 39.9 %, 23.9 % and 24.5 % respectively. On the whole, the ecological environment is of inferior quality in northwest and southwest Wujiang river watershed, but the ecological environment quality is better in the northeast. And the ecological environment quality in different regions has obvious differences.