Groundwater resources are becoming depleted due to climate change factors and non climate change factors. In order to effectively groundwater resources management, we developed a method for evaluating vulnerable periods of groundwater resource management in watershed areas. The watershed based vulnerability assessment was conducted independently of the evaluation of vulnerable areas and vulnerable periods for sub watersheds. The vulnerable area evaluation index was standardized and applied to the independent vulnerable period index each region. It was applied to Bonghwa-gun, Andong-si, Yecheon-gun, Mungyeong-si and Sangju-si in the upstream of the Nakdong river basin. As a result, the Sangju-si’s August was the most vulnerable at 0.278, and Andong-si was assessed to be vulnerable to groundwater resource management during 8 months of the year in study area. Using the developed method, we can find efficient management method considering the time and regional of groundwater resources.