Evaluation of Water Quality of Small Forest Watershed Runoff of the Upper Watershed of the Miyun Reservoir

Based on the grey analysis of water quality of the small forest watershed which located in the upper watershed of the Miyun reservoir of Beijing mountain area. Its results show that one of them water quality is IV degree becomes it was polluted by the mercury, the rest of them show that the water quality degree are II or I, and its also show that the grey correlation coefficient of forest watershed runoff quality varied with the forest cover ratio, the more high forest cover ratio of the forest watershed its grey correlation coefficient more bigger than the whose lower cover ratio, regardless of the nature or artificial forest.