4 major river watersheds

Korea has 4 major river watersheds. Han, Nakdong, Geum, and Youngsan river.

Precipitation and Runoff

Korea’s annual precipitation is about 12hundred millimeters and it is 1.4 times of the world’s average. On the contrary, annual precipitation per capita is about 26 hundred cubic meter which is one eighth of the world’s average.
Korea has large fluctuation and variation of rainfall. For example 2/3 of annual precipitation is concentrated during the summer season. Because of this, it make hard to manage water resources properly.

Annual Precipitation : 1,245mm
(1.4 times greater than the global average)
Per capita precipitation : 2,591㎥
(1/8 of the world’s average)
Ranked 17th out of 30 OECD nations

2/3 of the annual rainfall concentrated in summer, dry in spring and fall
　 - In Japan 1.4 times larger than Korea but evenly distributed throughout the year
Frequent floods and droughts because of the fluctuation of annual precipitation

The total amount of water resources is about 124 billion cubic meter. Total runoff is 72.3 billion cubic meter and out of this only 20 billion cubic meter flows during non-flood period. Actually only 27% of the rainfall is used as stream, dam and ground water.

Variance of water quality

The variance of water quality of four major river in Korea is shown in this table and it is also shown the variance of sewerage treatment rate in Korea. Through this chart, the water quality is improved by installing more wastewater treatment plants.