The purpose of this study is to evaluate the water pollution degree in the Mid-Nakdong River watershed regarding to landcover types using GIS method. As a result of landcover classification, rate of urban appeared highly on Daegu Metropolitan city. Also, rate of agriculture showed highly in the riparian zones of the Nakdong and Guemho River and rate of forest appeared highly in the borders of the study area. To identify the groups of watershed with similar landcover patterns using the Cluster Analysis.
According to the cluster analysis, the fifty sub-watersheds were grouped in three clusters, "Urban watershed", "Agriculture watershed", "Forest watershed". The proportion of urban area in each cluster had a positive correlation with water pollution degree.
Otherwise, the proportion of agriculture in the Agriculture watershed had a high positive correlation with water pollution degree. Therefore, it is necessary to estimate environmental capacity of water quality considering ecological and environmental characteristics of watershed ecosystem and expand water quality monitoring systems to small stream.