Water resources have always been important in Korea because of its long history of agriculture, and have remained an essential element for in- dustrialization and urbanization during the 20th century. Industrialization progressed along rivers that had plenty of water, such as the Hangang and the Nakdonggang. According to the National Long-Term Water Resources Plan (2011 – 2020), the total amount of water resources in South Ko- rea (including inflow from North Korea of 2.3 billion m3) is 129.7 billion m3. Of that amount, 75.3 billion m3 are usable after losses from evapo- ration and other factors. Due to seasonal variation in precipitation, about 56.0 billion m3 (43%) are gained during the heavy rainfall season (June to August), and about 19.3 billion m3 (15%) are gained during the other seasons.

After accounting for the amount discharged into the seas, 33.3 billion m3 are available for use in streams, dams, and groundwater. Dams account for 18.8 billion m3 (56.5%) of the total amount of water use, while streams account for 10.8 billion m3 (32.4%) and groundwater accounts for 3.7 bil- lion m3 (11%).

Dams built to store water are common in Ko- rea because of seasonal changes in precipitation. Dams may be categorized based on the purpose of water use: irrigation dams for farming, drinking water dams for living and industries, hydraulic power dams for electricity generation, estuary banks for water preservation and ood prevention, balancing reservoir dams for water level contro