Geography

The Republic of Korea is a peninsula located between the People’s Republic of China and Japan. It lies between the latitudes 33° 6’ N and 38° 31’ N and has many islands along the west and south coastlines. The total territorial area of Korea is 99,373 Km². Korea is a mountainous country and high mountains are located along the eastern part of the peninsula. Most plains and hilly areas are scattered in the western and southern parts of the country. The eastern coast of the Korean Peninsula has steep slopes, simple shorelines and deep-water depth. But there are many islands and irregular shorelines in the western and southern coasts. Tidal range of the western coast is very high and tidal flats are well developed. Many tidal land reclamation works were implemented in the past and a good potential for tidal land reclamation widely prevails.

Population and land use

The population of Korea was 51.8 Million in 2019 as per Population Reference Bureau (2019). Korea is one of the most populated countries showing the population density of 463 persons/Km² in 1997. The population engaged in agriculture in 1997 was 4,468 thousand persons or 9.7% of the total population. Due to the fast industrialization and rapid expansion of urban areas, the percentage of population in the agricultural sector has sharply decreased during last several decades. The average size of farm holding has been steadily increased from 0.97 ha in 1977 to 1.37 ha in 1997 mainly due to decrease in farm households and with the Government’s continuous efforts. Forest area is 64,410 Km² or 64.8% of the total area. Rivers, roads, residential area, industrial sites, and others occupy the rest. Out of total land area, the cultivated land covered 19,235 Km²; paddy fields (11,629 Km²) and upland (7,606 Km²) in 1997. The remaining 80,138 Km² was occupied by mountainous areas (64,413 Km²) and other uses (15,725 Km²).

Climate and rainfall

Korea lies within the temperate zone between the People’s Republic of China and the Pacific Ocean. Summer is hot and humid, while winter is cold and dry. The climates of spring and autumn are moderate and dry. A long drought from winter to spring or a severe spring drought often threatens transplanting of rice which is carried out in May or June. The monthly average temperature is higher than 20°C during the summer months from June to September and it falls below freezing point during the winter months from December to February. Temperature also varies with the location, showing high in the southern part and low in the northern part. The southeast wind prevails in summer and the northwest wind in winter. Annual average precipitation is 1,274 mm and the annual precipitation varies greatly year by year ranging from 754 mm to 1,683 mm. More than two third of the annual precipitation occurs during the summer months from June to September. Typhoons originating from the Pacific Ocean pass the peninsula mainly in August and September.

Food and agriculture

Agriculture is mainly developed in the south-western part of the country. While 19,235 Km² or 19.4% of the total area are arable, the area under grain production, except rice, is continuously decreasing as they have low profitability. On the contrary, the area of land used for growing vegetables and fruits and for greenhouse farming, which can yield more profit is increasing. The main crops grown in the irrigated uplands are economically profitable orchards, vegetables, and other horticultural plants. The vegetables are now normally cultivated in the irrigated uplands to increase production. Food crops grown in addition to rice are barley, soybeans, red bean, green bean, sweet potato, potato, maize, millet and sorghum. There is very little wheat cultivation because of the lack of competitiveness and therefore it is largely imported. The cultivable area is relatively small. Most of it has already been reclaimed and is intensively cultivated. In 2009, the total cultivated area was about 1.79 Mha, of which 1.59 Mha consisted of annual crops and 0.20 Mha of permanent crops.

Irrigation and drainage

It was known that rice culture in the Korean Peninsula began in the fourth or third century BC. From the beginning, most irrigation water was obtained from rivers and streams by constructing small reservoirs, diversion weirs or feeder canals. Many irrigation and flood protection facilities such as small dams, diversion weirs, canals, river embankments, etc. were continuously constructed by the central governments, local governments or farmers for many centuries up to 20^th century. In 1996, out of a total irrigated area of 888 800 ha the area served by surface water was an estimated 843 500 ha (95%) of which 65% was fed by 18,000 reservoirs, 21% by 6,000 pumping stations, and 14% by 18,000 headworks. The area served by groundwater accounted for 45,300 Ha (5%). In 2007, the irrigation potential area was taken as being the same as the total cultivated area, or 1,782,000 Ha, since it was considered that all cultivable land was under cultivation. In 2002, total irrigated area was around 880 400 Ha, a reduction compared to 1996, since some land has been diverted to other purposes such as construction of public facilities, houses and factories. Surface drainage and sub-surface drainage systems with either open ditches or pipes or culverts with gravitational drainage are provided to remove excess water from paddy fields. Where gravitational drainage was not possible, pump drainage was used. Levees and sea dikes were constructed to protect inundation of farmlands from external water such as river floods or spring tides of the sea. Intercept drains were installed to divert excess water drained from outside highlands. The drainage area improved by these means totals to 14,000 Ha.

Water resources management

Divides of watersheds of the major rivers are in the eastern part of the peninsula. So major rivers flow long distance from east to west or from north to south through low valleys and plains and become good irrigation water sources. The average annual precipitation in Korea is 1,274 mm and it indicates 126.7 Bm³ of water in volume. The average annual runoff is 69.7 Bm³ (55%) and the annual volume lost by evaporation or others is about 57 Bm³ (45%). More than two-third of the annual runoff occurs during the flood season from June to September and so a great amount of the water becomes unusable. Total available surface and ground water is estimated at 47.2 Bm³ which includes 23 Bm³ of river flows during the non-flood season, 10.8 Bm³ of stored water in multipurpose dams and agricultural reservoirs and 13.4 Bm³ of ground water. Yearly water use amounts to  about 30.1 Bm³; 14.9 Bm³ (50%) for irrigation, 2.6 Bm³ (9%) for industrial water, 6.2 Bm³ (20%) for water and 6.4 Bm³ (21%) in stream flow augmentation. Half of the total water use comes from agricultural use. In Korea, groundwater is not a major source of irrigation water and it covers less than five percent of irrigated land. Groundwater is often used as +supplementary irrigation water during drought periods.

Water policies

The main institutions involved in water resources management and in irrigation and drainage include the Ministry for Food, Agriculture, Forestry and Fisheries (MIFAFF), the Ministry of Environment (MOE), the Ministry of Land, Transport and Maritime Affairs (MLTM), the Rural Development Corporation (RDC), the Federation of Farmland Improvement Association (FFIA), the FLIAs and the WUAs. The mandate of MIFAFF is to provide consumers safe agro-food in a stable manner, strengthen agricultural competitiveness. The RDC is a semi-autonomous agency, which carries out the planning, study, design, and supervision of the rural infrastructure projects. The FFIA is a public corporation, which mainly carries out the planning, design, and supervision of the farmland improvement projects. WUAs are organized by farmers for the O&M of small irrigation system.

ICID and National Committee

The Republic of Korea became ICID’s member in 1969 and established the Korean National Committee on Irrigation and Drainage (KCID). KCID gave five Vice Presidents to ICID: Mr. Yu, Kuen-Hak (1993-1996); Prof. Soon-kuk Kwun, (2000-2003); Dr. YooMan HUH, (2004-2007); Prof. Kim, Tai-Cheol, (2011-2014); and Mr. Bong Hoon Lee (2014-2017). The 1^st Asian Regional Conference was organized during 16-21 September 2001 at Seoul, South Korea. The KCID also organized the 22^nd International Congress on Irrigation and Drainage during 14-20 September 2014 at Gwangju, Republic of Korea.