PREDICTING INFILTRATION AND GROUND-WATER MOUNDS FOR ARTIFICIAL RECHARGE

Planning systems for the artificial recharge of ground water via surface infiltration requires site investigations to predict infiltration rates and land requirements. Also, the ability of the vadose zone to transmit water to the underlying aquifer must be assessed, and aquifer conditions must be evaluated to predict the rise of ground-water mounds and to determine where ground water must eventually be pumped up again to prevent ground-water mounds below recharge areas from rising too high. A simple technique is presented to convert data from short-duration single-cylinder infiltrometer tests to final infiltration rates for large areas. Also, simple equations are developed to estimate heights of perched ground-water mounds above restricting layers in the vadose zone, to estimate how far from the recharge area ground water must be pumped, and to what depth to create a steady-state system with constant height of the ground-water mound in the recharge area. The procedures are useful for feasibility studies and the preliminary design of recharge projects, including long-term underground storage or water banking.