As Jangma (intensive rainy season in Korea) started, the people's eye focused on the sites of the Four Major Rivers Restoration Project, because it is the first natural test that our transformed rivers encounter. After the typhoon went away, the sites were all under control. The lowered level out of dredging served its role greatly in this rainy season. Therefore, despite torrential rainfalls in some area of Gyeongbuk and Chungcheong, there were not big damages as much as we concerned.
Typhoon in June proved the Four Rivers ‘Flood-proof’
This year’s summer is analyzed that there will be more frequent torrential rainfalls with a larger amount of rain than average. As the first 'attack', the Typhoon named Meari in June and subsequent rainy season were enough to make those concerned with the Project tense and nervous. And paradoxically, this torrential rainfall became a good opportunity to simulate the effect of the Project. From June 22 to 27, it rained on total 207.7mm in national average. So to speak, it is equivalent to 20 billion ton reaching 17% of annual rainfall. Despite the concerns about safety on the sites of the Four Rivers, the damages turned out to be meager. Particularly, the northern area of Gyeongbuk Province, Daejeon and some areas of Chungcheong region had no considerable damages. It is thanks to the effect of lowered flood level out of dredging.
The sites have already experienced lowered flood level from dredging 420 million m³ soils. According to the survey of Ministry of Land, overall water level proved to have been lowered: 2.55 m in Yeoju (the Han River), 3.5m near Sangju (the Nakdong), 0.84m in a vicinity of the Buyeo Weir, and 1.12 m near the Seungchon Weir of the Yeongsan River. The constructions of weirs are to be completed by late June - some delayed site will finish until July, so the condition of flood prevention can be said as improved. As to devastating flood damage, the safety level has been advanced in quantum leap. Before the typhoon and rainy season come, the sites got everything in readiness. Cofferdams and construction roads were taken away. Meanwhile, riverbed maintenance structures (structure for preventing riverbed from being eroded) were completed to be installed. Waterfront parks under construction were accelerated in its final touch. By the late June, dredged soils piled up on the terrace land of the river were moved outside of riverside area in order to prevent from crumbling and also to secure more space for water flow. We have looked into how they coped with the typhoon in June and what was the result.
