Spatio-temporal characterization of the Pliocene aquifer conditions in Wadi El-Natrun area, Egypt

Abstract

Wadi El-Natrun area has recently undergone extensive urban and agricultural expansion. Due to the absence of natural surface irrigation supplies, the only source of water in the area is the Pliocene groundwater aquifer. As a result, secondary salinization from increased abstractions is the major threat to the groundwater aquifer. There is a dire need for efficient strategies to ensure longterm sustainability of the area's productive agriculture. These strategies should be based on scientific spatiotemporal monitoring and analysis of the groundwater conditions that is also lacking. To capture the spatiotemporal variability in groundwater conditions, field measurements of total dissolved solids, electrical conductivity, pH, temperature, and water level as well as lab-based ionic composition were performed on 47 groundwater samples collected during 2006 and 2007. Determinations of the hydrochemical characteristics, water types, salt assemblages, and the sodium adsorption ratio were carried out on the samples. Reference data sets recorded in 1973 and 1997 were available for the area and were used to monitor the changes occurred in these periods. Geographic information system (GIS) was appraised for mapping and for integrated analysis of the different layers. Remotely sensed change detection techniques were applied to the Landsat TM and the ETM ? imageries and used to highlight the extensive reclamation and urbanization and to find key trends for the alterations in the groundwater conditions and their spatial association with land covers. Results revealed a topographic depression-induced flow pattern, predominance of leaching and dissolution processes, the presence of saline lakes, over-pumping from the Pliocene aquifer, and temporal changes in land uses are the main factors combined to control the spatio-temporal variability in the groundwater. Results also clarified the presence of two: northwestern and southeastern zones that varied distinctively in their hydrodynamic and hydrochemical characteristics. The northwestern zone showed an average water level decline of 15 m, the water of which is brackish (av. 2,037 mg/l) with dominant Na ? , Cl -and SO 4 2-ions. The groundwater of this zone is characterized by high to very high salinity hazard and high to very high alkali hazard and is not recommended for irrigation on soils with poor drainage and without proper management for salinity control. The southeastern zone showed water level decline less than 2 m, the water of which is fresh (av. 424 mg/l) with major Na ? , HCO 3 -, Cl -, and SO 4 2-ions, and quality suitable for irrigation with medium to high salinity and low to medium alkali hazards. The article represents the first step towards an integrated management of Wadi El-Natrun groundwater resources within a GIS framework.

Identification of Hydraulic Parameters of Wadi El Natrun Pliocene Aquifer Using Artificial Neural Network

“…The Pliocene aquifer is local in extent, covers the entire Wadi El Natrun area, and is discontinuously covered by Quaternary deposits of the Pleistocene Aquifer. As a result, the Pliocene aquifer is considered to be partially confined [20]. The Pliocene Aquifer's thickness ranges from 150 to 300 m thick [20].…”

“…As a result, the Pliocene aquifer is considered to be partially confined [20]. The Pliocene Aquifer's thickness ranges from 150 to 300 m thick [20].…”

“…Nonetheless, multiple studies have observed both local and regional groundwater flow to be concentrated toward the base of the valley where it discharges to eleven saline lakes [20].…”

Assessing the Cost of Groundwater Degradation in the Urbanizing Desert Area of Wadi El Natrun

“…Groundwater resources have been extracted from the study area in excess of recharge, the water table has been falling and salinization has been observed (Ibrahim 2005 ;Masoud and Atwia 2011 ) .…”

Distribution and immobilization of heavy metals in Pliocene aquifer sediments in Wadi El Natrun depression, Western Desert

“…The largest lakes are Lake Al-Ja'ar in the northwest and Lake Umm Rishah in the southeast direction. The water evaporates in amounts of up to 70 × 10 6 m 3 /year (Masoud and Atwia 2011).…”