Modelling of Hydro-Mechanical Coupling in Land Uplift Due to Groundwater Recharge

Abstract

Artificial groundwater recharge is used to increase groundwater in areas with water scarcity. After groundwater recharge, the water table rises, causing ground surface uplift from the increased pore water pressure in an aquifer. To manage groundwater resources effectively, understanding the hydro-mechanical features of aquifers during groundwater withdrawal and recharge is necessary. In practice, an artificial pool can be used to collect surface runoff so that it infiltrates the aquifer and recharges groundwater. Additional studies are required to understand the effect of various parameters on groundwater recharge and ground surface uplift. This study used the finite difference software FLAC 8.0 to examine the influence of the initial degree of saturation and soil type on the rate of groundwater recharge and ground surface uplift in an aquifer. Each aquifer was in an unsaturated state before groundwater recharging; therefore, groundwater recharge analyses were simulated by the two-phase flow in an unsaturated porous media. The results showed that the ground surface uplift was the largest when the initial degree of saturation was 70%, sequentially followed by a saturation of 60 and 50%. The influence of the initial degree of saturation was negligible on the cumulative groundwater recharge volume during the study period. Regarding the influence of soil types on ground surface uplift and the cumulative groundwater recharge volume, the results indicated that the sandy aquifer had the largest cumulative groundwater recharge volume during the study period. However, the ground surface uplift in the sandy aquifer was minimal.