T.M. Missimer, W. Guo, R.G. Maliva, J. Rosas, K.Z. Jadoon
Environmental Earth Sciences, volume 73, issue 12, pp
Aquifer storage and recovery, Wadi aquifers, Dams, Recharge, Groundwater modeling
channel recharge to the underlying alluvial aquifer is
naturally limited by the flashy nature of flood events,
evapotranspiration losses of water from the vadose zone, and aquifer
heterogeneity, particularly low vertical hydraulic conductivity.
Anthropogenic lowering of the water table in many wadi aquifers has also
reduced the potential recharge by increasing the thickness of the
vadose zone, causing interflow water loss from surface emergence and
evaporation. A method to enhance recharge is to slow the flow within
wadi channels by placement of dam structures, thereby ponding water and
increasing the vertical head gradient to create a more rapid rate of
infiltration and percolation. Effectiveness of wadi dams to enhance
aquifer recharge reduces over time due to mud deposition within the
reservoir caused by storm events. Up to 80 % of the water in old wadi
reservoirs is lost to free-surface evaporation before infiltration and
recharge can occur. One method to maintain or increase the rate of
recharge is to convey clean water by gravity flow from the reservoir
down-gradient to artificially recharge the aquifer using existing wells.
This type of system is a low-cost and low-energy recharge method which
could greatly enhance groundwater storage in wadi aquifers. Modeling
results show that existing wells could store up to 1,000 m3/day under gravity-feed conditions and up to 3,900 m3/day with the shut-in of the well to produce a pressurized system.