The total water use of Korea increased more than six times from 5.12 billion m3 in the 1960s to 33 billion m3 in the 1990s. This steep rise can be attributed to population growth, economic advance- ment, increased industrial development, and an in- creasing number of irrigation facilities. Accordingly, channel maintenance ow also increased to protect water quality, ecosystems, and landscapes. Since the 2000s, however, the rate of increase for water usage has been slowing down.

In 2007, agricultural use accounted for the larg- est proportion of total water use at 48%, followed by domestic use (23%), channel maintenance ow (23%), and industrial use (6%). Domestic and in- dustrial water usage remained about the same since 1998, while agricultural use experienced a decrease over the same time period. On the other hand, chan- nel maintenance ow – which is used for maintain- ing river functions – has gradually increased.

As of 2011, the Hangang watershed was record-