Changes in shallow groundwater levels and hydrochemistry according to depositional environment, river water level and groundwater pumping in the riversides

Two small basins (lower area "A" and upper area "B"), which are located in the Sincheon-Baekcheon watershed, show differences in the changing pattern of shallow groundwater levels and quality due to a various depositional environment and aquifer hydraulic features, after damming at the barrage in the Nakdong river. Groundwater levels in the zone "A" show a remarkable and sharp fall when groundwater pumping because of a fine-grained sediment composition with a low permeability. This closed-type basin does not facilitate groundwater discharge into the river during keeping high level and therefore shallow groundwater levels should be maintained Increased contents of anion in groundwater after damming also indicates the inflow or mixture of surface water in this zone. However, the zone "B" shows shallow groundwater levels and small fluctuation due to coarser deposits, and little change in groundwater quality despite of damming This indicates that groundwater levels and quality in the riversides are influenced by the basin shape, sediment composition and groundwater pumping condition due to an interaction between river water and groundwater.