Groundwater and River Interaction Parameter Estimation in Saigon River, Vietnam

Abstract

The Saigon River system is one of the largest resources contributing water supply for domestic and industrial fields in the Ho Chi Minh City and Binh Duong Province where the drought issue are occurring at downstream area in recent years. To manage the water resources in Saigon Basin effectively, the groundwater and river interaction parameter needs to be assessed systematically. However, in the past researches, the parameters seem to be less described with full understandings. In this study, a groundwater modeling of the main stream of Saigon River was applied to analyze groundwater and river interaction parameter along the river. The interaction layer was defined as a combined layer by materials of riverbed and materials of aquitard or aquifer. The values of conductance, through groundwater model calibration by piezometric heads during 2000 to 2007 at three cross-sections in Saigon River, were used to estimate the interaction parameter (K_iM^-1) at correlative cross-section. A function of interaction parameter with ratio of wetted length (R_w) was developed to estimate interaction parameter at each cross-section along Saigon River. When river cross-sections has no penetration to the aquifer and the materials of interaction layer consists of materials of riverbed and aquitard, the value of interactions is equal to 0.0003 d^-1. In the other hand, the value will be reach to 0.254 d^-1 when river cross-section has fully penetration to the aquifer. The interaction parameter function developed was applied to investigate the flow in and out between river and aquifer in the study area. In the upper part of Saigon River, river gained water from inflow of groundwater through riverbed (river gain) and lost water to groundwater (river loss) by outflow through the riverbed in the lower part during 2000 to 2007 and the river recharge to the first aquifer supplies to the second aquifer to supplement the aquifer storage discharged from the pumping.