El-Qaa Plain Research Articles

Estimating natural groundwater recharge taking into consideration temporal and spatial variability for arid unconfined aquifer

ABSTRACT Water scarcity is one of the major critical affecting arid climate countries. In addition, population growth and climate change are threatening the sustainable development of water resources in the upcoming decades. Therefore, managing groundwater can solve water scarcity such that sustainable development is ensured for future generations. Hence, it is crucial to assess the current quantity of groundwater by analyzing groundwater variables. Thus, natural groundwater recharge could be utilized as an indicator to assess groundwater quantity conditions. This study aims to estimate natural groundwater recharge in an arid unconfined aquifer. El-Qaa plain in Sinai, Egypt was chosen as a case study. Recharge was estimated taking into consideration spatial and temporal variability. To accomplish this, the WetSpass (Water and Energy Transfer between Soil, Plants, and Atmosphere under quasi-Steady State) model was applied. The model was run using morphological, landuse – land cover and climate data from 1986 to 2015 with a monthly time step. To calibrate the model, the isotope signature of δ18O and δ2 H of water was analyzed to determine the natural groundwater recharge of the aquifer. The obtained recharge value was utilized as a reference value for the calibration process. The results were validated using a finite-difference groundwater flow model (MODFLOW). The recharge values were imported to MODFLOW followed via a transient run from 2000 to 2011. The validation was conducted by comparing the simulated groundwater level with the observed ones. After validation process, the inter-annual and seasonal variability of recharge were determined, and a relationship between recharge and other hydrological parameters was deduced. In addition, the recharge distribution was mapped to depict the recharge spatial variability. The results show that the current recharge rate ranges from approximately 8.10 to 16.62 mm/yr, with a mean annual recharge rate of nearly 12.36 mm/yr. The study might be useful for hydrogeologists for determining potential recharge in the study area, groundwater modelers for developing a reliable groundwater flow model, and decision-makers for planning appropriate future sustainable development through water resources management.

Enhanced groundwater availability through rainwater harvesting and managed aquifer recharge in arid regions

Climate change in desert areas and semi-arid watersheds may offer a promising solution for the water scarcity problem that Bedouins and local inhabitants face. This study investigated the integrated water resources management in arid and semi-arid regions using rainwater harvesting in combination with the managed aquifer recharge (RWH-MAR) technique. The study also used recharge wells and storage dams to achieve the sustainability of groundwater supplies in the context of climate change and management of the flow to the Gulf of Suez. Therefore, different return periods of 10, 25, 50, and 100 years were considered for the annual flood volume resulting from those watersheds. Moreover, hydrologic modeling was carried out for the El Qaa plain area, South Sinai, Egypt, using the Watershed Modeling System (WMS) and the groundwater modeling of SEAWAT code. Our findings show that for different scenarios of climate change based on return periods of 10, 25, 50, and 100 years, the aquifer potentiality reached 24.3 MCM (million cubic meters) per year, 28.8 MCM, 36.7 MCM, and 49.4 MCM compared to 21.7 MCM at 2014 with storage of groundwater ranges 11.8%, 32.1%, 69%, and 127.4%, respectively. These findings have significant implications for the system of RWH-MAR and groundwater sustainability in El Qaa Plain, South Sinai. The RWH-MAR proved to be an effective approach that can be applied in different water-stressed and arid regions to support freshwater resources for sustainable future development and food security, as well as protect communities from extreme flash flood events.

Geo-environmental factors controlling groundwater hydrogeochemistry, salinization and quality in El Qaa plain coastal aquifer, Southwest Sinai, Egypt

El Qaa plain is one of the promising areas for agriculture projects, owing to its soil and groundwater resources. So, 14 groundwater samples were collected, chemically analyzed, hydrochemical (ratios, models and plots) and GIS techniques were applied, to evaluate the factors governing this water chemistry and suitability for irrigation. The results indicated the expansion of the agricultural area 8 times in the last 2 decades. The water can be divided into two groups; (A) freshwater (TDS ≤ 1000) in the eastern part of the study area within the clastic weathered basement rocks part of the aquifer, and (B) saline water (TDS > 1000) in the western part within the carbonates and evaporites rich sediments and close to the Gulf of Suez. The deduced factors controlling groundwater chemistry were precipitation, evaporites dissolution, seawater intrusion and ion exchange process. The calculated sodium absorption ratio (SAR) was < 10 indicating the good quality of this water for irrigation without sodicity hazard. Water of Group (A) (electric conductivity < 2250µS/cm) can be used safely for irrigation without any impact of salinity on all types of soil and plants. Group (B) water (electric conductivity > 2250µS/cm) has salinity hazard and can be used for irrigation on well-permeable soils and salt-tolerant plants. The concentrations of the studied potentially toxic elements (PTEs) were within the permissible limit for irrigation. Expansion in agricultural activities has adverse impact on groundwater quality. So, eco-friendly fertilizers should be applied in this promising area with the application of hydrologic pumping advises to safe aquifer quality from the degradation.

Environmental Sustainability of Water Resources in Coastal Aquifers, Case Study: El-Qaa Plain, South Sinai, Egypt

Water resources management is a vital need in arid and semi-arid regions such as Sinai Peninsula, Egypt. Accordingly, the sustainability of water resources in this arid environment should be examined in terms of the possibility of groundwater recharge, particularly through runoff water, while identifying the most appropriate potential sites for drilling new water wells to cover current and future needs. The aquifer system of El-Qaa Plain in South Sinai is considered one of the structural basins associated with the tectonic setting of the Gulf of Suez. It is the main source of high-quality water in South Sinai. The present work provided an integration of mathematical flow modeling, hydrochemical composition, environmental isotopic signature, watershed modeling system (WMS), and remote sensing (RS) tools to determine the aquifer sustainability and recharge mechanisms. The obtained results indicated the following: (a) the salinity of the water ranged between 326.4 and 2261 ppm, while the environmental isotope values ranged between −6.28 to −4.48‰ for δ18O and −29.87 to −21.7‰ for δ2H, which reveals the phase of recharge and mixing between ancient water and recent rainwater; (b) sites for three dams in three sub-watersheds were proposed to harvest approximately 790,000 m3/y of runoff water to enhance groundwater recharge of the aquifer system; (c) and five scenarios using MODFLOW indicated that water drawdown is acceptable by adding 10 new production wells (discharge rate increased by 3600 m3/day). Moreover, increasing the recharge rate by 2% from the base case, leads to an increase in the piezometric water level with an average value of 0.13 masl, which reflects the positive effects of the proposed runoff water harvesting facilities. The integration applied in this work represents an integrated management system for water resources (surface and groundwater) which is suitable for application in arid or semi-arid coastal and similar areas.

Monitoring and Integrating the Changes in Vegetated Areas with the Rate of Groundwater Use in Arid Regions

Frequent water table measurements are crucial for sustainable groundwater management in arid regions. Such monitoring is more important in areas that are already facing an acute problem with excessive groundwater withdrawal. In the majority of these locations, continuous readings of groundwater levels are lacking. Therefore, an approximate estimate of the rate of increase or decrease in water consumption over time may serve as a proxy for the missing data. This could be achieved by tracking the changes in vegetated areas that generally correlate with changes in the rate of water use. The technique proposed in this paper is based on two remote sensing datasets: Landsat 7 and 8 from 2001 to 2021, and Sentinel 2A from 2015 to 2021, as well as five vegetation indices: Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI), Soil Adjusted Vegetation Index (SAVI), Enhanced Vegetation Index (EVI), and Transformed Vegetation Index (TVI). The findings have shown that the datasets chosen performed best for small-scale land farms at the research location, which was chosen to be the El-Qaa plain, in the southwestern corner of the Sinai Peninsula in Egypt. Landsat 7 data with a resolution of 30 m revealed a substantial increase in land farms from 2.9 km2 in 2001 to 23.3 km2 in 2021. By using the five indices based on Sentinel 2A data, vegetated areas were categorized as heavy, moderate, or light. In addition, the expansion of each class area from 2015 to 2021 was tracked. Additionally, the NDVI index was modified to better reflect the arid environment (subsequently naming this new index as the Arid Vegetation Index: AVI). Rough scenarios of the increase in water consumption rate at the research site were generated by observing the increase in vegetated areas and collecting rough information from the farmers regarding the crop types.

Specifying the hydrogeological parameters range for a groundwater flow model in El-Qaa Plain aquifer, Sinai, Egypt

Hydrogeological parameters are very uncertain to specify in the groundwater flow models. Hence, it is important to specify a range for these parameters to be further utilized by the groundwater model users. In El-Qaa Plain, previous researchers have determined the hydrogeological parameters such as transmissivity, hydraulic conductivity, and mean annual recharge rate using geophysical methods, pumping tests, hydrological models, and groundwater flow models. However, they are also limited to specific locations and do not spatially distribute. In this paper, an effort has been accomplished to specify a specific range for the aquifer hydrogeological parameters using inverse groundwater modeling taking into account the spatial heterogeneity. These ranges could be taken into consideration during modeling groundwater flow. Hence, a finite-difference groundwater flow model has been applied using the ModFLOW model. Regularized pilot points method (RPPM) has been chosen as an inverse modeling technique to specify the accurate values of the aquifer parameters. Model-independent parameter estimation and uncertainty analysis (PEST) has been utilized to estimate the parameters. The results show that the geometric mean of the hydraulic conductivity in the study area ranges from proximity 1 to 2 m/day. Additionally, the geometric mean of the transmissivity ranges from nearly 200 to 500 m2/day. A relationship between the mean annual recharge rate and hydrogeological parameters has been determined. Besides, maps have been generated showing the spatial heterogeneity of the hydraulic conductivity. These maps could be further utilized by groundwater flow modelers to predict the potential of groundwater flow and pollution in the future.

Forecasting of Flash Floods Peak Flow for Environmental Hazards and Water Harvesting in Desert Area of El-Qaa Plain, Sinai.

Water resources in arid and semi-arid regions are limited where the demands of agriculture, drinking and industry are increasing, especially in drought areas. These regions are subjected to climate changes (CC) that affect the watershed duration and water supplies. Estimations of flash flooding (FF) volume and discharge are required for future development to meet the water demands in these water scarcity regions. Moreover, FF in hot deserts is characterized by low duration, high velocity and peak discharge with a large volume of sediment. Today, the trends of flash flooding due to CC have become very dangerous and affect water harvesting volume and human life due to flooding hazards. The current study forecasts the peak discharges and volumes in the desert of El-Qaa plain in Southwestern Sinai, Egypt, for drought and wet seasons by studying the influence of recurrence intervals for 2, 5, 10, 25, 50 and 100 years. Watershed modeling system software (WMS) is used and applied for the current study area delineation. The results show that the predictions of peak discharges reached 0, 0.44, 45.72, 195.45, 365.91 and 575.30 cubic meters per s (m3 s−1) while the volumes reached 0, 23, 149.80, 2,896,241.40, 12,664,963.80 and 36,681,492.60 cubic meters (m3) for 2, 5, 10, 25, 50 and 100 years, respectively, which are precipitation depths of 15.20, 35.30, 50.60, 70.70, 85.90 and 101 mm, respectively. Additionally, the average annual precipitation reached 13.37 mm, with peak flow and volume reaching 0 m3 s−1 where all of water harvesting returned losses. Moreover, future charts and equations were developed to estimate the peak flow and volume, which are useful for future rainwater harvesting and the design of protection against flooding hazards in drought regions due to CC for dry and wet seasons. This study provides relevant information for hazard and risk assessment for FF in hot desert regions. The study recommends investigating the impact of recurrence intervals on sediment transport in these regions.

Comparative Analysis of TMPA and IMERG Precipitation Datasets in the Arid Environment of El-Qaa Plain, Sinai

The replenishment of aquifers depends mainly on precipitation rates, which is of vital importance for determining water budgets in arid and semi-arid regions. El-Qaa Plain in the Sinai Peninsula is a region that experiences constant population growth. This study compares the performance of two sets of satellite-based data of precipitation and in situ rainfall measurements. The dates selected refer to rainfall events between 2015 and 2018. For this purpose, 0.1° and 0.25° spatial resolution TMPA (Tropical Rainfall Measurement Mission Multi-satellite Precipitation Analysis) and IMERG (Integrated Multi-satellite Retrievals for Global Precipitation Measurement) data were retrieved and analyzed, employing appropriate statistical metrics. The best-performing data set was determined as the data source capable to most accurately bridge gaps in the limited rain gauge records, embracing both frequent light-intensity rain events and more rare heavy-intensity events. With light-intensity events, the corresponding satellite-based data sets differ the least and correlate more, while the greatest differences and weakest correlations are noted for the heavy-intensity events. The satellite-based records best match those of the rain gauges during light-intensity events, when compared to the heaviest ones. IMERG data exhibit a superior performance than TMPA in all rainfall intensities.

Contribution of ASTER-TIR indices with geophysical and geospatial data for groundwater prospecting in El-Qaa plain area, Southern Sinai, Egypt

El-Qaa plain in the South Sinai is one of Egypt’s promising regions for sustainable development. The groundwater forms the primary sources of development in this region. The present study aims to identify the groundwater resources in El-Qaa plain area, Southern Sinai, Egypt. ASTER-TIR indices (Carbonate Index, Quartz Index, and Mafic Index) combined for the first ones with geophysical and geospatial data using fuzzy overlay spatial model (FOSM) to define the potential zones of groundwater in the area of study. The resultant model was tested and validated using the available well data of groundwater in the area of study. The results revealed that over 65% of EL-Qaa area is high to moderate with groundwater potentiality. The favorable areas for groundwater storing are nearly situated in the areas of high infiltration (high pixel values of carbonate and quartz indices) in the northwestern part of EL-Qaa area. Also, the regions in the central western, mid, and northeastern portions of the area of study where fractured rocks are dominant and reasonably higher rainfall. The results demonstrated the potential capacity of ASTER-TIR indices to assess groundwater potential in arid and semi-arid regions when integrated with other geospatial data as a reconnaissance tool.

The respective roles of modern and paleo recharge to alluvium aquifers in continental rift basins: A case study from El Qaa plain, Sinai, Egypt

Even though assessment of aquifer characterization and recharge mechanisms in rift-related basins, especially in arid environments, is essential for developing sustainable management strategies and food security assurance, a little attention has been paid to understand these parameters. In this manuscript, we utilize an integrated remote sensing, hydrological and isotopic approach together with previously published data to better understand the aquifer characteristics and the respective roles of modern and paleo recharge to the post-Miocene alluvium aquifer in El Qaa plain, which represents the eastern margin of the Gulf of Suez continental rift basin. Our findings indicate that: (1) the alluvium aquifer is largely formed of sand and gravels intercalated with silt and clay lenses and exceeds 500 m thick, (2) the groundwater salinity gradually increases towards the Gulf of Suez (from 402 to 5613 mg/l) with increasing the distance from the crystalline rocks bounding the alluvium-dominated plain, (3) isotopic analysis reveals that all of the groundwater samples show mixed isotopic signature between modern and paleo waters (δ18O: −6.79 to −4.433‰, and δ2H: −46.36 to −21.99‰). Basin-scale hydrological parameters show that the aquifer receives an annual modern recharge of 39 × 106 m3 and isotopic mass balance calculations indicate that the modern water ranges between 20 and 70% of the total volume of water in the aquifer. We suggest three dam locations along the southernmost basins in El Qaa plain to enhance the modern recharge to the aquifer and to harvest surface runoff of an annual volume of 737 × 103 m3 sufficient to supply freshwater to 13 thousands of the residents of south Sinai. The present study suggests that topographically-driven modern recharge to rift-related basins is taking place with significant amounts even under hyper-arid conditions and calls for paying special attention to investigate the response of these aquifers to climate variability.

THE ECONOMIC AND FINANCIAL EVALUATION OF UTILIZATION A NON-CONVENTIONAL WATER RESOURCES FOR JOJOBA PLANT CULTIVATION IN EL-QAA PLAIN AREA, TUR SINAI

According to the global attention of conserving the environment and exploiting of its natural resources efficiently, and our limited share of River Nile water that estimated as 55 billion m3 annually, we must find alternative solutions to meet our needs of water resources, and to achieve the strategy of Egypt for sustainable development 2030. Therefore, this research concerns the examination of the potentiality of the benefit from non-conventional water resources in the development process in Sinai, especially at El-Qaa Plain area in Tur Sinai region, also aimed to evaluate the economic and financial dimension of use water resources in the cultivation of Jojoba plant due to its high economic and environmental value. Also, use the indicative and descriptive methods, as well as the analytical method of the collected data from different references and interviews, and calculate the economic feasibility of using these water in the cultivation of Jojoba by using some standards of economic and financial such as (NPV) and others. In addition to, conducting analyze the inflation impact on the results of the economic and financial analysis to determine the sensitivity of the proposed project's profits to price changes that may happen in the costs and revenues components through project life. The research shows that the project has an ability to withstand market fluctuations and prices change on costs and returns, and it proved that the cultivation of jojoba would achieve the expected economic and environmental benefits, which would contribute to achieving sustainable development according to the available water resources in the region. Keywords: Economic Evaluation, Financial Analysis, Feasibility, Jojoba, Sustainable Development, Tur Sinai.

Gamma-ray spectrometric investigation of north El-Tor area, southwestern Sinai, Egypt

Interpretation was executed on the airborne and ground spectrometric data of Abu-Zeneima/Al-Tor area for verifying the significant anomalies as it contains important targets for prospective nuclear materials. Airborne spectrometric survey revealed that younger granites, are characterized by increase in the three main radioactive elements up to 5.4% K, 10 ppm eU and 33 ppm eTh. The western part of the study area includes sedimentary section which contains uranium-bearing phosphate beds. They are characterized by increase of airborne uranium concentration up to 14.2 ppm without potassium or thorium enrichment. The airborne image maps for eU/eTh and eU/K as well as ternary composite map revealed also that there is a promising U-anomaly, associated with the sedimentary section.Detailed ground spectrometric survey for the Cretaceous Nubian sandstone in Wadi Araba indicated that it is characterized by eU content reaches about 34 ppm, while eTh attains only about 9.8 ppm and potassium is 1.2%. Therefore, the eU/eTh ratio, reaches to a value of 3.4. The same sandstone bed in Abu - Durba Formation possesses eU values reach 67 ppm, whereas eTh values attain 38 ppm and average of potassium is 0.5%. The eU/eTh ratio is about 2, indicates also enrichment of uranium. The eU reaches a concentration of about 40 ppm in limestone of Matulla Formation whereas, the eTh values attains about 3 ppm and average K is 0.1%. Therefore, the eU/eTh ratio reached 13, due to the limestone is phosphatic. High eU value reaching to 80 ppm is recorded in the limestone facies of Sudr Formation, while the eTh values up to 11 ppm and potassium of about 0.9% are recorded. The eU/eTh ratio value reaching 7.3 indicates the high P2O5 content. A high uranium content is recorded at the northeastern part of El-Qaa plain area in the Sudr Formation reaching 47 ppm, while low eTh values attaining 7.5 ppm and potassium of 0.1% are recorded.

The impact of the geologic setting on the Quaternary aquifer, El-Tur area, Southwest Sinai, Egypt

The groundwater extracted from the unconfined Quaternary aquifer is the main source of water supply in El-Tur area. The area is bounded from the east by the elevated basement complex of Southern Sinai and from the west by El-Qabaliyat Ridge. The wadis dissecting these highlands form effective watersheds of the Quaternary aquifer. These wadis form areas of focused recharge. Recharge also occurs directly via the Quaternary sediments covering El-Qaa Plain. Subsurface lateral groundwater flow from the fractured basement contributes significant recharge to the aquifer as well. The aquifer sediment facies affect the type and quality of groundwater. In the eastern part where the aquifer is composed mainly of gravel and coarse sand with fragments of weathered basement, the Na-Cl-SO4 water dominates. In the west where the facies change is rapid and complex, many water types arise. The base exchange index (BEX) is positive in this part reflecting the role of clay minerals in changing the water types via cation exchange. In the east where clays are insignificant in the aquifer, the BEX is negative. In the western part next to El-Qabaliyat Ridge, the wells discharging from the calcareous sand zone have low groundwater salinities compared to the wells discharging from the alluvium. In general, the groundwater salinity increases in the direction of groundwater flow from the northeast to the southwest which reflects the dissolution of aquifer sediments. The concentration relationships between the major ions on one hand and chloride on the other reflect the dissolution of calcium carbonates, precipitation of K- and Mg-bearing minerals, and cation exchange of Ca for Na on clay minerals. The hydrochemical models support these reactions. In addition, they show that the effect of evaporation on the recharge water in the western catchment is about four times its effect on the eastern recharge water which reflects the rapid recharge through the wadis draining the fractured basement. Moreover, the contribution from the eastern catchment in sample No. 23 is more than four-folds the contribution from the western recharge area. The stable isotopes (2H and 18O) show that the Quaternary aquifer is recharging from recent rainfall. However, upward leakage of Paleogene groundwater (depleted in 18O) also occurs. The groundwater level map shows strong overpumping impact especially in the areas close to El-Tur city.

Mapping of groundwater prospective zones integrating remote sensing, geographic information systems and geophysical techniques in El-Qaà Plain area, Egypt

The geospatial mapping of groundwater prospective zones is essential to support the needs of local inhabitants and agricultural activities in arid regions such as El-Qaa area, Sinai Peninsula, Egypt. The study aims to locate new wells that can serve to cope with water scarcity. The integration of remote sensing, geographic information systems (GIS) and geophysical techniques is a breakthrough for groundwater prospecting. Based on these techniques, several factors contributing to groundwater potential in El-Qaa Plain were determined. Geophysical data were supported by information derived from a digital elevation model, and from geologic, geomorphologic and hydrologic data, to reveal the promising sites. All the spatial data that represent the contributing factors were integrated and analyzed in a GIS framework to develop a groundwater prospective model. An appropriate weightage was specified to each factor based on its relative contribution towards groundwater potential, and the resulting map delineates the study area into five classes, from very poor to very good potential. The very good potential zones are located in the Quaternary deposits, with flat to gentle topography, dense lineaments and structurally controlled drainage channels. The groundwater potential map was tested against the distribution of groundwater wells and cultivated land. The integrated methodology provides a powerful tool to design a suitable groundwater management plan in arid regions.

Implementation of magnetic, gravity and resistivity data in identifying groundwater occurrences in El Qaa Plain area, Southern Sinai, Egypt

El Qaa plain is one of the areas that have been proved to be promising as to its soil and groundwater resources in the southwestern part of Sinai. This study was carried out to study the lateral and vertical variations in the subsurface lithologic properties in El Qaa plain area and delineating the subsurface structure that affecting El Qaa plain depression. Gravity, magnetic data, fifty-one (51) vertical electrical sounding (Ves’s) and Digital Elevation Model (DEM) map were used. Two-dimensional density modeling, analytical signal, tilt derivatives, Euler deconvolution techniques and interpretation of the resistivity data were applied on potential data. This study concluded that, El Qaa plain is a NE-SW depression confined by two normal faults and subdivided into five sedimentary units. Rock fragments and boulders derived to the plain from the surrounding highlands are the main components of the first surface unit that characterized by high resistivity values. This layer is overly another unit composed of gravelly sand with thickness ranging between 10 and 140m. The third unit is composed mainly of sand with intercalations of clay with thickness ranging from 2 to 152m. A Reefal limestone unit is a fourth unit interpreted from this study. The fifth unit is composed of clay. The water bearing formations in El Qaa Plain area are located principally in the second and the third layers. Finally, the depth to the basement surface ranges from 400m to more than 1.5km below sea level. Also, there are many minor structural trends interpreted from this study and affecting the El Qaa plain are striking in N–S, E–W and NE-SW directions.

Assessment of scaling formation during solar desalination using PHREEQC modeling in El Gebail and El Qaa plain areas: southwest Sinai

The fresh water needs of mankind in regions under severe stress due to scarcity of water and energy can be satisfied if saline water which is available is converted to potable water by solar desalination. Beside salinity, scaling formation is one of the major problems that slow down heat transfer and cause system failures. Prevention and minimizing scale formation is highly important in the thermal solar desalination. So, the present study aims to studying individually the chemical characteristics affecting groundwater quality in inland and coastal regions of El Gebail and El Qaa plain areas southwest Sinai to evaluate and map them as feed water for thermal desalination plants. In addition, preparation of scale prediction modeling to estimate deposits on heat exchanger surfaces in distillation units has also been covered. Twenty-four water samples were collected from the study area and chemically analyzed. Water samples in El Qaa plain are of good water quality and can be used for different purposes. Water samples in El Gebail have excess salts for major wells and cannot be used without desalination. Saturation indices for different minerals are carefully studied. The scale prediction based on PHREEQC modeling was employed. In addition, laboratory experimental for evaluation scale precipitation after different recovery percentages of pure water from saline water was used. Results indicate that about 31 % of water samples in El Gebail region are faint coating, 38 % are mild scale forming, and 31 % are mild corrosion. Also, using PHREEQC for simulated evaporation with continuous water feeding of water sample can be used as a technique to quantitatively estimate the impending scale formation in solar desalination systems, which is very important to discover the best location for carrying out solar desalination. Also, the best operating procedure conditions and the best system designs were identified.

Geophysical Constraints on the Hydrogeologic and Structural Settings of the Gulf of Suez Rift-Related Basins: Case Study from the El Qaa Plain, Sinai, Egypt

Groundwater has been identified as one of the major freshwater sources that can potentially meet the growing demands of Egypt’s population. Gravity data (from 381 ground gravity stations) were collected, processed, and analyzed together with the available aeromagnetic (800 line-km) data to investigate the hydrogeologic and structural settings, areal distribution, geometry, and water storage of the aquifers in El Qaa coastal plain in the southwest Sinai Peninsula, and to assess their longevity given projected extraction rates. Findings include (1) complete Bouguer anomaly and total magnetic intensity maps show two connected sub-basins separated by a narrow saddle with an average basin length of 43 km and an average width of 12 km; (2) two-dimensional modeling of both gravity and magnetic data indicates basin fill with a maximum thickness of 3.5 km; (3) using anomalous residual gravity, the volume of water in storage was estimated at 40–56 km3; and (4) progressive increases in extraction rates over time will deplete up to 40 % of the aquifers’ volume in 200–230 years and will cause the water quality to deteriorate due to seawater intrusion in 45 years. Similar geophysical exploration campaigns, if conducted over the entire coastal plains of the Red Sea and the Gulfs of Suez and Aqaba, could assist in the development of sound and sustainable management schemes for the freshwater resources in these areas. The adopted techniques could pave the way toward the establishment of sustainable utilization schemes for a much larger suite of similar aquifers worldwide.

LAND SUITABILITY ASSESSMENT FOR SOME SPECIFIC CROPS USING REMOTE SENESING AND GIS IN EL-QAA PLAIN, SOUTH SINAI, EGYPT.

In Egypt, the excessive population growth and the lack of food security were the guide to increase production in unit area, expand the cultivated land horizontally, and to utilize the land with respect to its potentiality in an appropriate way. Therefore, this study aims to integrate soil qualities (or characteristics) with remote sensing data and Digital Elevation Model (DEM) into a Geographic Information System (GIS) to produce a database for the land resources and the soil map, and assess the current and potential suitability of some specific crops in El-Qaa plain, South Sinai, Egypt. Two SPOT5 images were classified using unsupervised classification technique. The base map of the study area was used in the field to check, confirm, correct and modify the physiographic mapping unit boundaries. Four sample areas were selected. 26 soil profiles were taken to represent the different mapping units in the study area. Morphological description and soil sampling were collected for laboratory analyses. The physiographic units were classified into subgroup level on the basis of the key to soil taxonomy. the results show that soils in the study area include: sand sheet (Low, moderate, and high) classified as Typic Torripsamments and Typic Haplosalids, Bajada classified as Typic Torripsamments and Sodic Haplocalcids, Basin classified as Typic Torriorthents, Wadi classified as Typic Torripsamments and Sodic Haplocalcids, Dry sabkhas classified as Typic Aquisalids, and Wet sabkhas classified as Sodic Psammaquents. The main land qualities of the different mapping units were selected and crop requirements of 21 crops were rated and matched to obtain the current and potential land suitability. The suitability of the selected crops currently not suitable in the different mapping units. The main limiting factors are texture, salinity and alkalinity, nutrient availability and calcium carbonate content, only in sabkhas added flooding, drainage, and soil depth. The potential suitability in the different mapping units refers that soils can be highly (S1), moderately (S2), and marginally (S3) suitable with a proper management practices and fertilization, and can not be suitable due to soil texture in all mapping units except in sabkhas where the limiting factors are texture, salinity and alkalinity, flooding, drainage, and soil depth which can not be enhanced in the near future. The results obtained can be employed by landuse planners (decision makers) to select areas suitable for the selected crops production.

Identification of the shallow subsurface succession and investigation of the seawater invasion to the Quaternary aquifer at the northern part of El Qaa plain, Southern Sinai, Egypt by transient electromagnetic data

ABSTRACTThe phenomenon of seawater invasion is a very common and widespread environmental problem that is present in the majority of Egyptian coastal aquifers. Saltwater intrusion may occur due to human activities and by natural events such as climate change and sea level rise. El Qaa plain is a structural depression trending NNW‐SSE, parallel to the main rift system of the Gulf of Suez. The Quaternary aquifer in El Qaa plain is the main source for water supply in this region. So, this study has been conducted to shed more light on the description of the subsurface section and marking out the invasion of seawater to this aquifer at the northern part of El Qaa plain. In this concern, transient electromagnetic data were measured at 52 stations arranged along 2 parallel profiles, 10 km apart, trending NE‐SW to cross the major course of the plain and to be approximately perpendicular to the coast line of the Suez Gulf. In addition, information from a nearby borehole was used to confirm the results of transient electromagnetic data interpretation. Two apparent resistivity pseudosections and two geoelectrical cross‐sections were constructed along the selected profiles. Investigation of these sections revealed that four geoelectrical layers could be detected in the shallow subsurface medium at the studied area and the Quaternary aquifer has been affected by seawater invasion at the western and middle parts. Besides, three faults striking approximately NW‐SE parallel to the major track of the plain were inferred from this study. These faults may be controlling the groundwater accumulation and flow in this area.

Hydrogeophysical study of the El Qaa Plain, Sinai, Egypt

The paper reports a study of the Quaternary aquifer in the El Qaa Plain using gravity, magnetic and geoelectric surveys. One hundred and twelve gravity and magnetic stations were measured and interpreted. The area is dissected by faults with orientations consistent with the Gulfs of Suez and Aqaba and the Nile valley. Groundwater data indicated an E–W flow and an increase in salinity toward the Gulf of Suez. The Piper diagram indicates that the water type of the El Qaa plain is Na–Ca–Cl–SO4 and the hydraulic conductivity of the aquifer 50 m/day. The calculated effective porosity is about 43.1%.