Recharge Dynamics

Recharge investigations have focused primarily on estimating recharge rates in ephemeral channels, known locally as wadis, in response to infrequent flash flood events.  In collaboration with Drs. Alan Fryar of The University of Kentucky and Farouk Soliman of Suez Canal University, the WRRS group deployed an array of soil temperature probes to monitor and characterize the magnitude and timing of recharge in Egypt and Morocco.  This research provides a framework for determining recharge rates, identifying flooding events, and understanding the groundwater-surface water interactions in arid environments. The recent research applies thermal satellite remote sensing techniques to place the localized field results into a larger regional context.

WRRS research also investigates regional estimates of groundwater abstraction and the subsequent effect of land subsidence using GRACE satellite data and persistent scatterer radar interferometry.  Radar interferometry uses multiple satellite radar scenes to dampen the noise components (e.g., atmosphere, vegetation) and results in a strengthened signal of land deformation.  In collaboration with Dr. Lhouissane Bouchaou of University Ibn Zohr in Morocco, we determined the magnitude and spatial distribution of land subsidence caused by excessive groundwater pumping in Souss Basin, Morocco.  These results have allowed them to develop better long-term water management strategies and apply this technique to other basins in Morocco.

Understanding recharge mechanisms and subsurface flow paths are integral to  understanding factors that govern the timing and distribution of recharge.  In collaboration with Dr. Ahmed Al-Dousari of the Kuwait Institute for Scientific Research in Kuwait, we determined the primary recharge mechanism in Kuwait is focused or localized recharge which collects in drainage depressions where rapid infiltration occurs.  These results were combined with other hydrogeologic parameters (e.g. infiltration tests, groundwater head) and satellite remote sensing to develop a methodology for identifying freshwater lenses in areas underlain by saline aquifers.

In collaboration with Drs. Mohamed Sultan of Western Michigan University and Abdou El Magd of KAUST in Saudi Arabia, we helped to prove the hypothesis that modern recharge to the Nubian Aquifer is occurring in Egypt.  Field investigations and water sample collection and analysis in Wadis Baraga and Zalaga positively identified the presence of subsurface water using near-surface geophysics (electrical resistivity and VLF) and stable isotope (O18, D2) systematics.  The flow paths and timing of recharge events over the past 50,000 years were identified and the timing of previous recharge events during previous wet climatic periods (African Humid Period in the Holocene) to the historically fossil aquifer was constrained using paleo recharge temperatures derived from nobles gases (He, Xe, Kr) and radioactive isotopes (C14).

Projects & Research

Insight into Wadi Properties, Dynamics, and Interconnectedness During Flash-Flood Events using TRMM Satellite Data and Soil Temperature Probes in Sinai Peninsula, Egypt:

Geologic and Hydrologic Settings for Development of Freshwater Lenses in Arid Lands:

Toward a better understanding of palaeoclimatic regimes that recharged the fossil aquifers in North Africa: Inferences from stable isotope and remote sensing data:

Modern Recharge to Fossil Aquifers: Geochemical, Geophysical, and Modeling Constraints: