3 Depressions Found at the Top of Mt. Keumgang Dam

The government officially admitted that the Mt. Keumgang Dam could be overflowing when it has a torrential downpour over 300 mm a day. If the sand dam made of sand and pebbles is overflowing, it could be collapsed in the worse case.

Particularly, according to the data of the Chuncheon Meteorological observatory, the region has a record of 308.5 mm on July 25th, 1991, the possibilities of the collapse cannot be excluded.

However, no damage is anticipated in the lower area of the Han River even when the Mt. Keumgang Dam is collapsed since the Peace Dam (total pondage 559 million tons) and Hwacheon Dam (total pondage 1 billion 50 million tons) could save the water.

The Ministry of Construction and Transportation announced yesterday that the government will set up a general plan for the Mt. Keumgang Dam, including such measures to complete the reinforcement work of Peace Dam and to maintain the volume of the water in Hwancheon Dam at a present state, 400 million tons.

In addition, anticipating that 620 million tons of water will be short by the block of the North Han River in the North area, the government is planning to request for a joint management of the North Han River. If the North rejects it, the government will raise the height of Peace Dam and build another dam in Han River.

According to the Ministry of Construction and Transportation, by the rapid increase of the water influx to Hwacheon Dam from 2 tons to 273 tons per second up to total 340 million tons during Jan. 17th – Feb. 4th, the government surveyed the related materials including the satellite photos of the Mt. Keumgang Dam and found 3 depressions at the top of the dam.

One of the depressions (width: 20 m, depth: 15 m) and a smaller depression might be a hollow made by a false construction or in the process of repair.

The Ministry analyzed that the dam was constructed in 16 months, which is quite shorter than the required construction period of 2 years and 6 months, and therefore, the problems arose in the process of containing waters when the dam was not completed yet.

In addition, since the extra water paths to drain the water when the water level is too high is built at 110 m high, they are useless for the current Mt. Keumgang Dam (105 m high). Therefore, when it rains over 300 mm a day, the dam is possible to be collapsed.

Kim Chang-Se, director of MCT, said that `the critical point for collapse may be the 1.2 billion tons of water and the dam currently contains about 590 million tons of water. However, the computer simulation for the case of collapse, Peace Dam and Hwacheon Dam could absorb the impact by containing 590 million tons and 650 million tons of water respectively. If when the Mt. Keumgang Dam is collapsed, the lower areas than Hwacheon Dam may not be affected at all.¡°

Jae-Seong Hwang jsonhng@donga.com