Pumped Well Drainage System Effects on Mitigating Barrage-Induced Inundation Problems in Low-Lying Plains

The construction of a new barrage, the Gangjeong-Koryeong Barrage, in the Nakdong River and related sluice-gate operation has resulted in higher river-water and groundwater levels in the floodplain, which has caused the land to become swampy. The barrage construction caused changes in the groundwater flow direction and amounts of inflow and outflow between the river and surrounding area. The river has been the source of most of the groundwater in the riparian zone due to river leakage (from 96 to 1,975 m3/day) since being dammed. Two methods were proposed to lower the groundwater level in the swampy area: a drainage channel system and a pumping well system. Numerical simulations to assess the effectiveness of each method were performed, and the pumping well system was shown to be the more effective of the two. Following the construction of a drainage system consisting of eight pumping wells, the groundwater levels returned to predam levels. This study shows that the hydrological effects of high river-water levels in the riparian zone need to be examined thoroughly when a river barrage is designed and constructed.