Starting from the Taebaek Mountains, flowing through Gangwon, Chungcheong, Gyeonggi Provinces, Seoul and Incheon, ending in the West Sea, the Han River has total length of 514km and basin area of 26,219m2. In 1970, when Korea was rebuilding its economy in the aftermath of the Korean War, the world praised Korea's dazzling growth as the'Miracle of the Han River.' The Han River, the source of life-giving water for 23 million metropolitan populations as well as that of industrial water that pumps the heart of midland industrial region, has many problems such as environment. The Han River restoration is not only limited to reconstruction of ecology and prevention of flood. If the river, which moves along three provinces (Seoul, Gyeonggi, Gangwon), becomes clean, Korea's economy, culture, and living quality will be improved.
The weir, which is built across the river as a low barrier holding to control waters for agricultural and life purpose, has been one of the typical water controlling methods in Korea.Among the sixteen weirs planned in the four rivers, three multifunctional weirs along the Han River, Ipo weir, Yeoju weir, and Gangchon weir are already under construction.
The Han River is divided into the Bukhan River (Northern Han River) and the Namhan River (Southern Han River) at Dumulmeori. Dams in the Bukhan River, such as Soyang Damand Cheongpyeong Dam, which are critical in flood control ofthe Han River, are familiar, but in the Namhan River, there are fewer dams (Chungju and Paldang), so it is more vulnerable to water disasters due to Typhoon or rainfall.
The master plan of Four Major Rivers Restoration has the following blueprint for the Han River, which is used by the half of Korean population: it is to improve water quality by adjusting elevated watercourse due to accumulation of soil,and to increase agricultural water by 10 million m3 through improving existing 12 agricultural reservoirs and to gain 40million m3 water through establishing functional weirs.
The multifunctional weirs, which just have been started construction, play traditional role for preventing and controlling flood, as well as that of small-scale hydroelectric power plantthat uses water resources and landmark that reflects each region's cultural assets.
Flood control method so far is preventing water from overflowing by building banks. However, the Four Major Rivers Restoration Project will try more fundamental method by lowering river bed, which is elevated by accumulation. The Han River will be lowered by 0.4m to 3.9m, and there would be no need to worry over overflow in case of heavy rain.
Construction of water retention along the river will be preparedto control the amount of water flowing into the mouth. Also,safety will be improved by reinforcing 131km long old banks.
It is expected that watercourse adjustment is finished asplanned, the river will return to the status in which people can swim.
