The transboundary non-renewable Nubian Aquifer System of Chad, Egypt, Libya and Sudan: Classical groundwater questions and parsimonious hydrogeologic analysis and modeling

Clifford I. Voss; Safaa M. Soliman

doi:10.1007/s10040-013-1039-3

Home/Archive/USGS

USGS · 70046429

The transboundary non-renewable Nubian Aquifer System of Chad, Egypt, Libya and Sudan: Classical groundwater questions and parsimonious hydrogeologic analysis and modeling

Clifford I. Voss·Safaa M. Soliman

View original source ↗Export metadata ↓

Abstract

Parsimonious groundwater modeling provides insight into hydrogeologic functioning of the Nubian Aquifer System (NAS), the world’s largest non-renewable groundwater system (belonging to Chad, Egypt, Libya, and Sudan). Classical groundwater-resource issues exist (magnitude and lateral extent of drawdown near pumping centers) with joint international management questions regarding transboundary drawdown. Much of NAS is thick, containing a large volume of high-quality groundwater, but receives insignificant recharge, so water-resource availability is time-limited. Informative aquifer data are lacking regarding large-scale response, providing only local-scale information near pumps. Proxy data provide primary underpinning for understanding regional response: Holocene water-table decline from the previous pluvial period, after thousands of years, results in current oasis/sabkha locations where the water table still intersects the ground. Depletion is found to be controlled by two regional parameters, hydraulic diffusivity and vertical anisotropy of permeability. Secondary data that provide insight are drawdowns near pumps and isotope-groundwater ages (million-year-old groundwaters in Egypt). The resultant strong simply structured three-dimensional model representation captures the essence of NAS regional groundwater-flow behavior. Model forecasts inform resource management that transboundary drawdown will likely be minimal—a nonissue—whereas drawdown within pumping centers may become excessive, requiring alternative extraction schemes; correspondingly, significant water-table drawdown may occur in pumping centers co-located with oases, causing oasis loss and environmental impacts.

Explore related subjects

Hydrogeology Journal Article

Source-reported bounding extent: 7.44° to 33.29° latitude; 9.39° to 38.7° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Clifford I. Voss, Safaa M. Soliman. 2013-11-06. The transboundary non-renewable Nubian Aquifer System of Chad, Egypt, Libya and Sudan: Classical groundwater questions and parsimonious hydrogeologic analysis and modeling. https://doi.org/10.1007/s10040-013-1039-3

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Characterization of subsurface groundwater pathways from treated wastewater effluent infiltration along the South Rim of Grand Canyon National Park, Arizona, USA

Recharge of treated wastewater to the environment is increasingly becoming a component of water resources management, especially in water-limited areas such as the Grand Canyon. Treated wastewater from the Grand Canyon South Rim Wastewater Treatment Plant has been discharged to a dry wash located along the surface expression of a fault for decades, but the fate of the wastewater is unclear. Previous research suggested possible connections between the treated wastewater discharge sites and springs along the South Rim of Grand Canyon, particularly Monument spring. Additional investigations presented in this report add further evidence to the connection between the wastewater and Monument spring, utilizing per- and polyfluoroalkyl substances, artificial sweeteners, and stable isotopes of water. A dye trace established the first direct connection between wastewater and Monument spring where the dye added to treated wastewater took about 4–6 months to move through the subsurface and was detectable for 5 months. The persistence of wastewater tracers over time and the timing of dye movement suggests a fast subsurface flow pathway. On the basis of geologic observations of faults and jointing, groundwater flow follows a possible combination of karst and other structural pathways. The dye and wastewater tracers were monitored at other springs along the South Rim of Grand Canyon and the combination of repeated dye detections and multiple wastewater tracers were only found at Monument spring. Multiple lines of evidence provide a robust tracer suite to support evidence of structural/karst controls on preferential flowpaths; faults alone are unlikely to explain the flow pathway.

Arizona↗

USGS2026

Regional and local controls on groundwater salinity in California’s southwestern San Joaquin Valley, United States: Insights from airborne electromagnetic surveys

The San Joaquin Valley is one of the most intensive oil and gas and agricultural production regions of the United States, yet the regional groundwater salinity distribution is not well defined, particularly near the western margin of the valley where salinity is highly variable. Airborne electromagnetic (AEM) surveys were conducted to improve the understanding of the three-dimensional variations in groundwater salinity in the upper 300 m. A salinity mapping approach representing geophysical and interpretational uncertainty was used to predict the probability of the occurrence of three salinity categories commonly used in water resource management (fresh, total dissolved solids (TDS) < 3000 mg/L; brackish, TDS 3000–10,000 mg/L; saline, TDS > 10,000 mg/L). The salinity mapping identifies regions of fresh and brackish groundwater near oil fields, suggests potential gaps in groundwater monitoring, and supports improved fresh and brackish groundwater resource availability estimates. Shallow saline regions are common near historical lake beds and marsh areas, with abrupt transitions between saline and fresh/ brackish groundwater in both historical and modern hydrogeologic contexts. The common occurrence of a shallow saline groundwater inversion implies that reliance on single-depth salinity threshold maps may lead to overestimation of the availability of fresh and brackish groundwater. Some parts of these saline areas can be correlated to chemical indicators of oil-field water, likely resulting from historical surface disposal of produced water.

California↗

USGS2025

Review: The hydrogeology of critical mineral resources relevant to the energy transition

Attaining the goals of the international treaty on climate change (the Paris Agreement) will greatly increase the demand for the critical minerals required to implement clean-energy technologies. This poses both challenges and opportunities to the hydrogeologic community from several perspectives. Here, important insights that the hydrogeological sciences have to offer for mineral exploration, mineral production, and addressing environmental issues related to mining and mine decommissioning are summarized. This study focuses on copper, cobalt, lithium, and rare earths to represent the broad spectrum of critical minerals and illustrate their relevance by referring to projected demands and production rates. The current understanding of the hydrogeologic processes that form major deposits of these minerals are then summarized. Ore is defined as the naturally occurring material from which minerals of economic value can be extracted, where most ore deposits are the products of complex hydrogeologic couplings between fluid flow, heat transport, solute transport, chemical reactions, and mechanical deformation. Exploration models for the discovery of deeper, hidden deposits are potentially informed by hydrogeologic theory and hydrogeochemical processes. Hydrogeologic understanding and methods are also essential to production and recovery. Longstanding challenges are mine dewatering and (conversely) mine water supply, as well as mineral-extraction practices such as spoil heap leaching and in situ mining. New challenges arise from element extraction from subsurface brines. Finally, the quantity of water use and potential environmental impacts of mining on water quality are at the core of ‘social license’: the approval and acceptance of society to mining activities.

Hydrogeology Journal↗