> Water Resources in Korea > Basic Features
  Korea gets an average precipitation of about 1,283 annually, which is 30 percent more than the world average, 973mm. This may seem sufficient until you factor in Korea's high population density. The average annual precipitation per capita is 2,705 which is about 10% of the world average of 26,800m3
  Korea is now at a disadvantage due to the yearly, regional and seasonal variations of precipitation when it comes to managing water resources effectively.
The annual precipitation has tended to increase slightly over the past 100 years. Since the 1960s, the fluctuation of annual precipitation has increased at the same time with the increase of magnitude of droughts and floods.
Two-thirds of the annual rainfall is concentrated in the rainy monsoon period from June to September.
The annual average runoff is 73.1 billion m3, which constitutes 57% of the annual average precipitation of 127.6 billion m3. The runoff ratio of 57% is somewhat large value. Relatively topographic characteristics of Korea such as smaller basin area and steep slopes when we compare to the Unites States or the countries in Europe, and short length of rivers and heavy rainfalls in Korea cause large discharge in a short period. The monthly average runoff of June to September, as with precipitation, constitutes 2/3 of the annual volume.
Unlike overseas rivers, the flow of rivers in Korea is unstable due to large seasonal variations in precipitation and discharge. The coefficient of river regime of the Han River, before major dams were constructed, was 1:390, which is relatively larger than the Thames in Britain (1:8), the Rhine in Germany (1:18), and the Seine in France (1:34).
Yearly variations in precipitation : 754mm(1939)~1,782mm(1998)

a difference of 2.3 times

Areas : Gyungbuk province 1,000mm~Cheju Island 1,700mm

a difference of 1.7 times

Seasonal precipitation : two-thirds of the annual precipitation is concentrated between June and September. Thus there are floods in summer and droughts in winter and spring

A comparison of other countries' precipitation
World average
mean annual precipitation(mm)
precipitation per capita
  In Korea, an average annual precipitation of about 1,283 produces a potential water resources volume of 127.6 billion. However, 54.5 billion? or 43% of it is lost in the form of infiltration and evaporation and the remainder, about 73.1 billion or 57% is estimated to be annual surface runoff.

Of this amount, 49.3 billion is swept away by floods immediately, the remaining amount of water, 23.8 billion flows during normal periods.

Status of water use in Korea(Unit : billion/year)
  Groundwater development costs a great deal and can cause environmental damage as well as the pollution of groundwater. As the aquifer has not yet been well developed in Korea, there is a potential for a lot of large-scale developments on a regional basis.

Amount of usable groundwater : 13.3 billion per year

A used amount in 1998 : 3.7 billion per year

  Domestic wastewater and industrial wastewater have been increasing due to urbanization and industrialization. The overuse of fertilizer and insecticides in farming areas has led to serious pollution of rivers and streams nationwide. However, environmental infrastructure has been constructed with sustained investment and various attempts to remove water pollution have been implemented since 1990.


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