Anthropogenic Aquifer Recharge: WSP Methods in Water Resources Evaluation Series No. 5

Abstract

Vadose zone hydraulic properties impact the performance of surface-spreading MAR systems by controlling the rate of flow of water from land surfaceto the water table. Single- or double-ring or basin (pilot) infiltration tests are typically performed to estimate infiltration rates. Vadose zone hydraulic properties obtained from infiltration tests at land surface may differ greatly from those at depth, especially where the vadose zone is very thick. Evaluation of vadose zone properties is complicated by the zone being two phase (air and water), as opposed to the single-phase system of the phreatic zone. Vadose zone testing programs needs to consider the spatial variability in properties and the volume and area of investigation of tests relative to aquifer heterogeneity. Where project budgets and time are limited, the use of safety factors in design can compensate for uncertainty.