Field experiment of artificial recharge through a well with reference to land subsidence control

Land subsidence due to groundwater overdraft is one of the most urgent environmental dilemmas facing Bangkok Metropolis and its vicinities. Prolonged flooding, salt water encroachment, groundwater quality deterioration, damage to building foundations, roads, bridges etc. are some of the adverse consequences of the groundwater over-exploitation and the resulting land subsidence. Because the control of groundwater pumping within a safe limit is not likely to be achieved in the near future due to the poor town planning and rapid economic growth of the city, artificial recharge has been proposed as one supplemental means to help restore the declined piezometric levels and mitigate land subsidence. As the first step of recharging the Bangkok aquifer system, a field experiment aimed at investigating particular features of recharge into its uppermost aquifer, that is, the First Sand Layer, has been recently performed. The recharge operation was successfully carried out from October 1993 to June 1994, and some rebound in the recharged aquifer was recorded. The experiment provided useful guidance with reference to setting up of a field test, data monitoring and analysis which can be applied to other sites with similar conditions.