Surface water-groundwater interaction processes For groundwater pumping management in Saigon river basin

Abstract

Since the 1990s, the excessive extraction of groundwater of Saigon River basin is dramatically increased and groundwater resources of Saigon River basin have been facing dramatically drawdown groundwater level in the downstream area. The study attempted to develop groundwater modeling through employing SW-GW interaction parameters and incorporate the concept of sustainable pumping yield to detect optimal pumping management under growing water demand in Saigon River Basin.

According to field observed soil moisture, the study recognized the average monthly percolation rate of sand clay loam, sand clay, and clay varies 2-4.5 mm/day, 1.5-3.5 mm/day, and 0.5-2 mm/day, respectively to rainfall intensity 4-14mm/day. Besides, the conductance in riverbed is coressponded with the sand percentage of sediment. As consequent of the high pumping rate, the river recharge contributed 50% to groundwater budget in downstream. The developed groundwater modeling through employing SW-GW interaction parameters derived found that the groundwater sustainable yield in existing downstream and in upstream new area are 880,000 m3/day and 1.02 MCM/day, respectively.

Thus, the conjunctive water supply in Saigon River Basin is sufficient for land use based water demand (4.9 MCM/day), which utilize 3.5 MCM/day from surface and 1.4 MCM/day from aquifers. Meanwhile, water demand, based on World Bank’s estimate (6.9 MCM/day) is over the maximum conjunctive water supply of Saigon river basin which includes 4.2 MCM/day from surface river water, and 1.9 MCM/day from groundwater. Hence, Saigon River Basin should improve surface water capacity and/or utilize water saving/recycle technology to cover water shortage of 0.8 MCM/day