Groundwater in the Nile Delta

Egypt’s renewable water resources are limited to its share from the Nile River as well as some minor rainfall along the coastal areas. The Delta and the narrow valley of the Nile comprise 5.5% of the total area of Egypt. The Nile Delta aquifer, Egypt, which is replenished directly by the Nile water, is considered another renewable resource. However, this aquifer system is in direct contact with the Mediterranean Sea from the north and the Suez Canal from the east. Groundwater resources in Nile Delta are an essential source of freshwater due to increasing water demand and shortage in supply as a result of increasing agriculture, domestic, and industrial consumption. It provides about 85% of total groundwater abstractions in Egypt by 6.1 BCM per year. It is obvious that since 1981 the groundwater potentiality is decreasing annually in a linear fashion by 0.1 billion cubic meters. On the other hand, water quality in the irrigation and drainage canals is deteriorating as we move downstream due to the increased pollution load from the heavy agricultural activities and high population density. Agriculture, domestic, and industrial effluents are the main sources of contamination of the Nile Delta aquifer. The water quality of the Nile Delta aquifer has been assessed through testing some groundwater samples, surface canal water, and drainage water. All the studies showed that the concentration of most water quality parameters and heavy metals exceeded the WHO standards for drinking water, and some studies indicated the areas where the groundwater is not suitable for irrigation. There are damage and shortage in aquifer water quantity and degradation in the quality due to the gradual increase of groundwater pumping especially in the delta fringes. Also, problems were reported as a result of the continuous decline of the piezometric surface and the increase of the water salinities. This chapter gives an overview of groundwater resources in the Nile Delta aquifer. Detailed investigation of groundwater in the Nile Delta aquifer was presented.

The current Egyptian situation is framed by land and water scarcity, which are under severe pressure. The Nile Delta is one of the most densely populated deltas in the world. Soil and water resources are at the center of sustainable development and are critical for socio-economic development.

Nile Delta branches gain water from the aquifer in some reaches and lose water to the aquifer in other reaches. The flow directions between groundwater and surface water can change seasonally with variations of the water table level with respect to the level in nearby waterways. Available data on the evolution of the salinity of groundwater in the Delta indicate that the construction of the High Aswan dam resulted in a shift of salinity isolines towards the seashore, and that current pumping rates have not yet critically affected this balance. Possible localized over-pumping, however, results in “up-coning” of salinity from deeper layers. Contamination of groundwater by agriculture and more prominently by seepage from domestic and industrial effluents had already attained worrying levels. This may jeopardize the quality of the Nile Delta aquifer in the end. The increasing use of groundwater for irrigation poses a serious threat to food security and could lead to unaffordable prices of staple foods. Therefore, groundwater overuse rising could hit food prices. Aquifer depletion can induce significant environmental degradation, such as land subsidence and seawater intrusion. The amount of non-renewable groundwater used for irrigation was doubled in Nile Valley and Delta. The annual groundwater abstraction in the Nile aquifer system and fringes is about 4.6 billion m³. Another 0.5 billion m³ is abstracted from the desert aquifers and the coastal areas. Groundwater abstraction is expected to increase to 11.4 billion m³. Model output revealed that groundwater recharge has not changed significantly over time, while pumping has. Because of these trends, groundwater was estimated to be in a deficit of approximately 24 billion m³ (±15%) in year 2011, compared to year 1957.

Most of the Nile Delta soils are recent alluvial soils. The soils generally have a light to heavy clay texture. The clay content varies from 40% in the south to nearly 70% in the north. The soils located near the north coast and lakes are of marine and alluvial deposits. Close to the desert fringe on both sides of the Delta occurs the desert sandy plains, which are flat to undulating topography. The soils of the coastal plains and beaches are sandy with some low to medium longitudinal sand dunes. The salinity problem becomes more severe in the Delta as we approach the seacoast and lakes, due to the effect of the shallow, saline groundwater and the brackish water intrusion from the sea and lake. The old and young terraces of both western and eastern sides of the Nile Delta are of alluvial origin and non-uniform in nature. Most of the soils are originated from the ancient Nile sediments, which are mostly derived from igneous and metamorphic rocks of the Abyssinian Plateau. The soils are alluvial deposits of the Nile Delta (Qatabeya) and valley (Qena), swamps and fluviomarine-lacustrine deposits (El-Manzala), beach sands (Edku). The old alluvial soil is more developed than other soils.

Groundwater reportedly provides drinking water to at least 50% of the global population and accounts for 43% of all water used for irrigation. Food production requires the largest quantities of water, with groundwater resources providing more than 40% of all water used globally for irrigated agriculture. According to the Egyptian Ministry of Irrigation and Public Works the annual water resources in Egypt depend mainly on the Nile water (55.5 BCM), 5.5 BCM groundwater, and 1.3 BCM of rain water that falls on the agricultural land in the Delta. Most of the groundwater in Egypt is non-renewable except for the shallow groundwater in the Nile valley and Delta lands and its fringes in addition to some depression sources and oasis like Wadi El-Natrun in the west Delta (the Valley of Sodium salts) and Siwa oasis south of the northwest coast of Mediterranean. The main aquifers are generally formed of granular rocks (sand and gravel) or fissured limestone and rocks. The deep-lying aquifers systems is comprised of the regional Nubian Sandstone aquifer System, occupying much of the area of Egypt. The thickness of the sediments varies from a few hundred meters in the south, to 4,000 m west of Abu Mongar. Carbonate Aquifers occupy at least 50% of Egypt. The Moghra aquifer system has a broad geographical distribution in the region west of the Nile Delta and south of the Qattara depression. The Nile valley and Delta aquifer are the most productive, containing around 200 × 103 million m³ of water that is renewable by seepage from the Nile river irrigation systems. The thickness of this aquifer decreases from 300 m at Sohag Governorate in Upper Egypt to few meters near Great Cairo (Cairo, Giza, and Qalyubia governorates) and also in the south near Aswan. The coastal aquifer lies 35 km from the seashore, 45 km north of Cairo and is recharged mainly from rainwater and from high-pressure water in the Nubian Sandstone aquifer. Rose basement rock has the same characteristics as the Carbonate aquifer but is difficult to explore since it is very deep (1,200–2,000 m depth). The main problem of the Siwa oasis depression is the poor drainage and lack of a drainage outlet, thus causing water logging. The second problem is the shallow and under pressure groundwater that pops up to the ground creating wetlands. In Wadi-El-Natrun depression, the water table depth is almost of 3–5 m but has a high concentration in sodium carbonates and bi-carbonates. This type of composition is completely different in other delta fringes such as in Nubaria (west delta) or in Salhia (east delta) in which it ranges between 30 and 60 m with a medium quality of maximum salinity of 2,000 ppm. Most of these areas in Nubaria or Salhia are irrigated with Nile water through El-Nasr canal in Nubaria and Salhia canal in the east Delta, but the wells of groundwater are stationed as stand-by or alternative resources when Nile irrigation water is not sufficient or in case of a delay in its delivery.

Egypt is located in the arid and semiarid region, where the limited availability of renewable freshwater is the main challenge in future agriculture and urban development. The main water resource in Egypt is the River Nile; Nile water alone is no longer sufficient for the increasing water requirements for the different developmental activities in Egypt due to a rapid increase in population and expected impacts of climate change especially on the agriculture sector. The agriculture sector in Egypt is the main consumption of freshwater; it consumes more than 80% of the total water resources in Egypt. The role of groundwater is steadily increasing especially in the newly reclaimed areas along the desert fringes of the Nile Delta and Valley. Abstraction from groundwater in Egypt is dynamic in nature as it grows rapidly with the expansion of irrigation activities, industrialization and urbanization.

The quality of the groundwater in this area may be strongly affected by the impact of the sea level rise combined with changes of Nile River flows, leading to an increase in the salinity levels of groundwater. In addition, the current and future human activities, especially extensive and unplanned groundwater abstraction, are resulting in deterioration of the available groundwater resources. Serious negative socioeconomic impacts can follow as a consequence. In the Nile Delta, extensive groundwater abstraction is also a very significant factor that increases seawater intrusion. Groundwater wells which were beyond salinization zones in the past are consequently showing upconing of saline or brackish water.

There are many efforts from researchers to control groundwater level on farm via controlled drainage which contributes to water requirements for some crops like rice. On the other hand, shallow groundwater may cause soil salinization, waterlogging and damage to crop roots. Agriculture activity may cause pollution of groundwater with fertilizers and pesticides through seepage so integrated management for sustainable use of groundwater is a very important issue in the Nile Delta, so in this chapter the author will provide an overview of the exchangeable relationships between groundwater and agriculture in the Nile Delta region.

A total of 110 sediment samples were collected at various levels during the well drilling. Mechanical analysis of 70 sediment samples was done in order to study the sedimentological and depositional environments of the studied aquifer. Another 40 samples were subjected to X-ray diffraction (XRD) analysis to detect the mineralogical composition of the aquifer sediments. The sedimentary work revealed that the majority of the samples are medium to coarse clayey sand, moderately sorted and coarse skewed. This may support the multi-directional depositional currents. The present-day, wind action influences skin of the sediments. The samples lie within the field of river processes. Mineralogical analysis by X-ray diffractometry revealed that smectite is the most abundant clay mineral, followed by kaolinite, whereas illite is the less abundant clay mineral. The essential carbonate minerals are calcite and dolomite whereas non-carbonate minerals include quartz, feldspar, and hematite.

The present study is carried out in Nile Delta aquifer, where the data of electrical resistivity and gamma ray logs of the 34 well ranging in depth between 80 and 140 m were used to calculate the aquifer parameters. It is aimed to estimate the spatial variability of the formation lithology, porosity, permeability, groundwater salinity, and the hydraulic conductivity. Bilqas Formation showed an increase in the thickness, porosity, and water salinity to the north and northeast directions. Permeability and hydraulic conductivity values decrease in the same direction. Bilqas Formation ranges in thickness from 3 m in the southwest direction to 31 m in the northeast direction. The shale content and porosity ranges are 54% to 97% and 21% to 55%, respectively. This layer has low values of permeability (16 × 10⁻⁹ to 78 × 10⁻⁹ mD) and hydraulic conductivity (<2 × 10⁻⁹ cm/s). The water salinity of this layer ranges from 200 mg to 1,600 mg/l.

In Mit Ghamr Formation, average shale content ranges from 4.5 to 22%. Numbers of scattered clay lenses are detected in different places with high intensity in the northeastern direction. Porosity ranges from 19 to 39%. High permeability values are recorded in this formation and ranged from 0.1 × 10⁻² to 8.7 × 10⁻² mD. The water salinity average values in this aquifer range from 220 mg to 2,100 mg/l. The calculated hydraulic conductivity values for this formation are of range 5.082 × 10⁻¹⁰ to 2.134 × 10⁻⁸ cm/s. In this layer, the increase in the shale content, the increase in porosity, decrease in the permeability and hydraulic conductivity, as well as the increase in salinity, are to the northern and northeastern directions.

In coastal and semiarid regions, the scientific interest lies in imaging the saltwater intrusion and delineating freshwater aquifer zones, respectively. Direct current resistivity (DCR) and induced polarization (IP) geophysical methods are commonly used to assess hydraulic characteristics of the aquifer. Particularly, the main reason for hydrogeophysical application of both DCR and IP is that the electrical characteristics of aquifers depend mainly on the geometry of the pore space and the porosity controlling the soil and rock effective transport properties. For preliminary hydrogeological investigations, these methods are applied at a wide range of field and laboratory scales. Accordingly, the vulnerable zone to the saltwater intrusion and/or contamination can be characterized by high accuracy. Furthermore, empirical and semiempirical relationships are widely used to predict the aquifer petrophysical characteristics, e.g., hydraulic conductivity, using the inversion results of such electrical methods. Equally, conventional and nonconventional DCR inversion algorithms are developed to reduce the nonuniqueness problem of actual resistivity interpretation and, consequently, to obtain more meaningful models than previously reported. As case histories, this chapter demonstrates the efficiency of DCR method for hydrogeological assessment in Nile Delta, Egypt, emphasizing on technical constraints to achieve sustainable development in coastal and semiarid areas.

Establishing new communities is one of the strategic plans of the Egyptian government during the last decades. One of the targeted localities for such plan is the West Nile Delta area where it is considered as a promising area for creating new settlements. The area under investigation is located to the west of Nile Delta on both sides of the Cairo-Alexandria desert road, between latitudes 30° 17′ and 30° 42′ N and longitudes 30° 00′ and 30° 30′ E. It covers an area of about 1,825 km². To help such national plan, the present study aims to delineate the hydrogeological regime of the study area through qualitative and quantitative interpretation of the available electrical and electromagnetic data.

The geoelectric resistivity survey includes 93 vertical electrical soundings (VES) carried out using Schlumberger array with AB/2 ranging from 1.5 m up to 700 m in successive steps. The time domain electromagnetic (TEM) survey was executed near selected VESes where 26 TEM stations with loop spreading 50 × 50 m were measured.

The quantitative interpretation was conducted through one-dimensional resistivity inversion for both VES and TEM data using the software IX1D from Interpex Ltd. Ten cross sections (from VES data) and three cross sections (from TEM data) were constructed and well correlated with the available boreholes. The cross sections reveal that the depth to the main aquifer ranges from 6 m at the northern part near El-Nubariya city to about 90 m at the southern part. On the other hand, the aquifer system in the area is divided into Pleistocene and Pliocene aquifers. The Pleistocene aquifer which is the shallower aquifer is consisted of gravelly to clayey sand deposits. The Pliocene aquifer, deeper, is the main aquifer and composed of sand to gravelly sand deposits where in some places, it can be divided into two aquifers. Based on the inferred structural map, it is worth to mention that Wadi El-Natrun and its lakes are structurally controlled by faulting systems trending NW direction.

Serious salinization problem is affecting the northern Nile Delta basin and its groundwater aquifers. The hydrochemistry of major ions (K⁺, Na⁺, Mg⁺, Ca²⁺, Cl⁻, SO₄ ²⁻, HCO₃ ⁻, CO₃ ²⁻) and the trace elements (Fe, Mn, Zn, Pb, Cd, Cr, Cu, Ni) have been used to constrain the hydrochemical characteristics, source, and salinization processes of the shallow coastal aquifer, northwestern Nile Delta. Twenty groundwater wells, varying in depth from 17 to 40 m, had been examined and sampled to carry out the physicochemical parameters and chemical compositions of the groundwater and to obtain additional information on the possible contamination with major elements, trace elements (heavy metals), and nutrients (NH₄ ⁺, NO₃ ⁻, PO₄ ²⁻).

The hydrochemical data indicated that the groundwater of the coastal aquifer, northwestern Nile Delta, is meteoric in origin and is mixed with marine water. The coastal plain aquifer is recognized to be at high risk of increasing salinization. The salinity of the groundwater as a total dissolved solid (TDS) ranges from 1,288 to 4,907 mg/l with an average of 3,155 mg/l. The electric conductivity (EC) of the groundwater ranges from 1,900 to 9,790 μS/cm with an average of 4,620 μS/cm. It is directly related to TDS and the geographical position of each well. The groundwater is slightly alkaline with pH ranges from 7.01 to 8.2. The high salinity, pH, and EC values support the conclusion of seawater intrusion.

The nutrient content such as nitrates is higher than the standard values, which mainly resulted from rural sources. The concentrations of the trace elements are lower than the standard values except for iron, manganese, and nickel. This groundwater can be used for crop irrigation but must be treated before using for drinking.

Rapid population growth and mass migration from rural to urban centers have contributed to a new era of water sacristy, and a significant drop in per capita freshwater availability, resulting in the reuse of wastewater emerging as a viable alternative. The reuse of wastewater after treatment using the soil aquifer treatment (SAT) has recently gained popularity due to low operating/maintenance cost of the method. However, the presence of organic micropollutants (OMPs) may present a health risk if the SAT is not adequately designed to ensure required attenuation of the OMPs. An important aspect of the design of the SAT system is the large degree of natural variability in the OMP concentrations/loads in the wastewater and the uncertainty associated with the current methods for calculation of the removal efficiency of the SAT for the OMPs. This study presents a novel model for more accurate prediction of the removal efficiency of the SAT system for the OMPs and the fate of the OMPs trapped within the vadose zone. A large data set is compiled covering a broad range of aquifer conditions, and the SAT system parameters, including hydraulic loading rate and dry/wet ratio. This study suggests that removal of OMPs in SAT systems is most affected by biodegradation rate and soil saturated hydraulic conductivity, in addition to dry to wet ratio. This conclusion is reached by the application of the developed prediction model using data sets from the case study SAT systems in Egypt.

Groundwater is considered the main source of water in many coastal areas. The increase of water demands increases the abstraction from aquifers which has resulted in lowering water tables and caused saltwater intrusion. Coastal aquifers lie within some of the most intensively exploited areas of the world. Saltwater intrusion is one of the main causes of groundwater quality degradation and a major challenge in the management of groundwater resources in coastal regions. Saltwater intrusion causes an increase of salt concentration in groundwater which places limitations on its uses. Excessive pumping always leads to a dramatic increase in saltwater intrusion. In coastal aquifers, the hydraulic gradient exists towards the sea which leads to flow of the excess freshwater to the sea. Seawater intrusion is a special category of groundwater contamination that threatens the health and possibly lives of the people living in coastal areas. The problems of saltwater intrusion into groundwater had become a considerable concern in many countries particularly in coastal areas. Seawater intrusion leads to the depletion of groundwater resources and should be prevented or controlled to protect water resources in coastal regions. The intrusion of saltwater in coastal aquifers has been investigated by several methods including geophysical methods, geochemical methods, experimental studies and mathematical models. This chapter presents a brief history of saltwater intrusion in coastal aquifers. The Nile Delta aquifer is one of the largest underground freshwater reservoirs in the world that attacked by saltwater intrusion. Large amounts of freshwater were damaged by salinization. Extensive studies were carried out to investigate saltwater intrusion in Nile Delta aquifer using numerical and field studies. Most of these investigations revealed that the seawater intrusion in the Nile Delta aquifer has extended to a distance of more than 100 km from the Mediterranean coast. The effect of climatic changes including the rise in the sea level has a significant effect on the position of the transition zone, and the groundwater quality would deteriorate in large areas of the Nile Delta aquifer.

Seawater intrusion occurs in many coastal and deltaic areas around the world. When saltwater travels inland to production wells, underground water supplies become useless. Intrusion of saltwater is the most common contamination occurrence in coastal aquifers. A number of several methods have been used to control seawater intrusion to protect groundwater reserves in coastal aquifers. Extensive research has been carried out to investigate saltwater intrusion in coastal aquifers. Although some research has been done to investigate saltwater intrusion, however, only a limited amount of work has concentrated on the control of saltwater intrusion to protect groundwater resources in coastal areas which represent the most densely populated areas in the world, where 70% of the world’s population live. The coastal aquifers’ management requires careful planning of withdrawal strategies for control of saltwater intrusion. Therefore, efficient control of seawater intrusion is very important to protect groundwater resources from depletion. New methods to control saltwater intrusion in coastal aquifers are presented and discussed in details; also the advantages and disadvantages of each method were highlighted. Finally, control of saltwater intrusion in Egypt, especially in the Nile Delta aquifer, is discussed. The possibility of applying new methods to control saltwater intrusion in Egypt is presented.

The temperature-depth profiles of 47 boreholes were investigated to characterize the groundwater flow system in the northwestern part of the Nile Delta, Egypt (hereafter referred to as the study area). A vertical subsurface thermal system was used for the investigation.

The groundwater was recharged in the reclaimed area located in the southwestern direction of the study area, where high subsurface temperatures were recorded. The discharge regions were located in the old agricultural lands (northern and northeastern areas) and were characterized by low subsurface temperatures compared with those in the recharge area. This abnormal thermal system was attributed to contrasts in the surface air temperature, where higher values were recorded in the recharge area (Wadi El-Natrun station; annual average temperature 23.15°C) and lower values were detected in the old agricultural lands (Damanhour station; annual average temperature 20.37°C). Regardless of this unusual framework, the geothermal gradient was low in the recharge territory (average 0.0198°C/m) and high in the discharge area (average 0.0343°C/m).

The effect of irrigation canals on the thermal system was detected from the constructed vertical two-dimensional (2D) cross-sections, where the gaining streams were underlined by a warm zone, while the losing streams were underlined by a cooler zone. Vertical groundwater fluxes in the study area were assessed from a comparison between measured and simulated one-dimensional (1D) temperature profiles. All temperature profiles related to wells in the Wadi El-Natrun station area were of the recharge type, with groundwater flux (U) values ranging from 0.3 to 1.5 m/year, except for well 21, which was the discharge type (U range −0.1 to −0.5 m/year). The temperature profiles related to Damanhour station were of the discharge type (U range −0.1 to −1.5 m/year), except for wells 22, 47, and 39, which were the recharge type (U range 0.1 to 0.5 m/year).

We concluded that the geothermal gradient is superior to the thermal system for following the groundwater stream framework in regions such as those we examined.

Mapping of the boundaries between freshwater and saltwater was helpful in surface resistivity surveys because of the high electric conductivity of saltwater relative to freshwater. A total of 30 electrical soundings were measured to configurate the seawater intrusion. Accordingly, two zones of groundwater quality were delineated: the slightly freshwater zone in the southern part, with resistivity range of 15–90 Ω m, and the brackish water to saltwater zone, with a very low resistivity of <2 Ω m in the northwestern parts. In addition to tracing the freshwater-seawater contact zone, three geoelectric layers were detected. The surface layer composed of sand, clay, and silt. Its resistivity ranges from 5 to 512 Ω, and the thickness varies from 1 to 25 m. The aquifer layer is composed of sand with intercalations of clay with resistivity ranging from 15 to 90 Ω m and thickness from 25 to 120 m. The clay layer resistivity ranges from 2 to 15 Ω m and thickness from 2 to 69 m.

Several aquifers around the world are situated in the coastal zones and influenced by seawater intrusion. The development of populace in coastal territories and the conjugate increment in human, farming, and industrial activities have forced an increase in the needs for freshwater. The Quaternary aquifer in the Nile Delta is among the biggest groundwater aquifers in the world. Along its northern side, the aquifer is highly affected by the Mediterranean Sea. Because of the inordinate pumping in the course of the most recent couple of decades, the groundwater quality in the northern parts of the Nile Delta has been decreased extensively. Therefore, this chapter aims to trace the groundwater flow system and seawater intrusion in the study area using the multi-tracing technique. The integration between borehole temperatures and groundwater chemistry was good to conduct the aim of this study. Borehole temperature was measured in eight boreholes, and the groundwater was sampled from the same wells but sometimes from the shallow and deep zones. Tala well located to the south of the study area indicated the recharged fresh groundwater with downward flux of 0.8 m/year. The fresh groundwater started to discharge from south Tanta City till south Kafr Elsheikh City where the calculated upward fluxes were −0.1 to −0.5, − 0.35, and −0.23 m/year for Kafelarab, Nawag, and Elkarada wells. Hydrochemically, the groundwater in the area northern Kafr Elsheikh City is highly affected by seawater intrusion, and the measured temperature profiles are of discharge type, and their calculated upward fluxes were −0.6, −1.2, and −2.8 m/year for Kafr Mesaaed, Elhadady, and Motobes wells, respectively.

In comparison, temperature profile (Motobes well) affected by seawater intrusion has higher upward flux, while the freshwater recharge-type profile (Tala well) has lower downward flux. Hydrochemically, the seawater intrusion highly affected the wells from ElKarada wells to Motobes wells (northern Kafr Elsheikh City) and close to the Mediterranean Sea. Two types of saline water were recognized. The shallow groundwater is highly affected by seawater intrusion (TDS around 20 g/l), and the deeper groundwater is of hypersaline characters (80 g/l). These two types of saline water could deteriorate the groundwater quality in the Nile Delta in case of unresponsible severe pumping rates.

Groundwater in the Nile Delta aquifer is considered one of the most important water resources of Egypt. In the last 30 years, the abstraction rates from groundwater wells in the Nile Delta increased dramatically. The Nile Delta region is considered very vulnerable to the sea level rise in the Mediterranean Sea due to climate change. The main objective of this study is to build an integrated 3D groundwater model of the Nile Delta aquifer to simulate the saltwater intrusion under different climate change scenarios using the MODFLOW and SEAWAT programs with the actual irrigation canal network in the Nile Delta region. Also, it proposed different scenarios for management and control of saltwater intrusion in the Nile Delta aquifer. Google Earth Pro software was used to estimate the bank levels and top width of the irrigation canals within the Nile Delta region. The spatial and temporal variation of groundwater recharge from rainfall in the Nile Delta aquifer was estimated by using WetSpass hydrological model. ENVI software was used to come up with land use classification based on available land cover images of the Nile Delta for 1972, 1984, 1990, 2000, and 2009. The WetSpass model was calibrated by comparing the simulated groundwater recharge with the calculated one by using the water balance equation method. The results indicated close agreement in groundwater recharge between the two methods’ outputs. The WetSpass model was then applied in respect of 1970, 1980, 1990, and 2010 for the purpose of validation. The SEAWAT program was used to build an integrated groundwater model for the Nile Delta aquifer to simulate the saltwater intrusion where three scenarios are proposed: sea level rise, decreasing the south groundwater head due to additional groundwater pumping and combination of the two scenarios previously mentioned. The third scenario (combination between sea level rise and decreasing the groundwater head due to additional pumping) is the worst scenario. Finally, seven scenarios based on the built model results were proposed through decreasing the pumping discharges for management and control of saltwater intrusion in the Nile Delta aquifer. Reduction of the pumping discharges from all areas of the Nile Delta has a significant impact more than regional reduction and redistribution of pumping discharges in order to control the saltwater intrusion.

Lack of hydrogeological data is the main reason for the difficulty of groundwater management, especially in arid zones. Egypt’s Sahara Desert is located in Western Egypt and is lacking hydrogeological data. Recent development of the Egyptian Sahara is mainly due to the Nubian Sandstone Aquifer System (NSAS) as a unique source of water there. NSAS covers a great part of Egypt, Sudan, Chad and Libya and is considered as a main source of freshwater. During the last two decades, excess pumping of groundwater at the Egyptian Sahara brought about a significant drawdown of the groundwater table. This chapter will discuss a new technique that was developed to overcome the uncertainty from data gaps to facilitate the implementation of numerical models to improve strategies for optimal groundwater management. The core of this developed method is to understand the temporal and spatial variation of groundwater table. In the Egyptian Sahara, the hydrogeological data needed for groundwater simulation are lacking, thereby introducing a problem for numerical models calibration and validation. A newly developed model named the modified grey model (MGM) was proposed to analyse groundwater flow. At its core it is a finite element method (FEM) with a new developed modified genetic algorithm (MGA) to obtain the goodness of fit with observations. The MGM is an attempt to determine a selection process of the best input models’ trends with the appropriate values of input parameters for achieving acceptable fitting to the measured data. Kharga Oasis was selected as a case study for application of the developed MGM in groundwater flow analysis. The MGM simulation results clearly show that the future groundwater table will face a severe drawdown in the northeastern part of the study area compared with that in the southwestern part. On the other hand, by 2060, the hydraulic head difference between these two parts will reach 140 m. Considering the uncertainty and lack of available data, the MGM produced more realistic results compared with those obtained from only FEM. Three development scenarios of groundwater withdrawal were proposed. These scenarios include either expanding the current extraction rate or redistributing the groundwater withdrawal over the recent working production wells (RWPWs). The results concluded that, for the northern part of the oasis, the groundwater table could be temporally recovered to an economical piezometric level; however, the table in the southern part is severely decreased. Conclusively, the MGM could be applied to other cases with similar data limitations.

Egypt is continuously facing a decrease in water share per capita due to a decline in available water resources.

The objective of the present study is to evaluate and manage the groundwater resources of the Nubian Sandstone Aquifer System (NSAS) in the New Valley area. It is located in the middle part of Egypt’s Western Desert. It lies between latitudes of 24°–28° N and longitudes of 27°–31.5° E. It covers an area of 440 km long by 460 km wide where the total area is about (202,400 km²). A detailed review of the Nubian Sandstone Aquifer in the western desert is also introduced.

A finite difference model using “Visual MODFLOW” was applied on the Nubian Sandstone Aquifer of Dakhla Basin. It was adapted to simulate groundwater flow in such aquifer. The simulation was calibrated with available groundwater head data from CEDARE Report (2002). An optimum solution is established for the safe groundwater mining in the study area.

The scenario applications could allow for an increase in reclamation at Dakhla Oasis by 15%, with the condition of safe drawdown values less than 60 m for the period of 100 years.

The study provides the benefits of applying the modeling techniques. Numerous valuable inputs for the national development plan in Egypt are presented. The study found that it is important to seek an alternative water resource to compensate for the groundwater depletion.

The target of this work is to assess the impact of the human activities on the hydrochemistry and quality of the groundwater under Nile Delta villages. Sixteen groundwater samples were collected during 2016. Hydrochemical analyses including major and trace elements were done. Spatial distribution of the element concentrations according to WHO guidelines, WQI (drinking water quality index), and statistical analysis was used for assessment. The sampled groundwater showed variable quality from one village to another and was classified into three clusters. Cluster A is characterized by higher concentrations of total dissolved solids (TDS), electrical conductivity (EC), potassium, magnesium, sodium, calcium, sulfate, chloride, bicarbonate, Mn, Zn, P, NH₄, Ba, and unfit WQI values. Low water quality of this sample is related to the effect of El-Gharbia main drain and seawater intrusion. Cluster B included samples 4, 8, 11, and 15 and had the moderately mean ion concentrations and higher concentrations of Fe, Sr, and Si compared to the other two clusters. The latter cluster major ion concentration arrangement is sodium > calcium and chloride > bicarbonate. WQI of this cluster varies from poor, very poor to unfit.

Samples 1, 2, 3, 5, 6, 7, 9, 10, 12, 13, and 14 belong to cluster C which had the lowest ion concentrations and dominated by Ca > Na > Mg and HCO₃ > Cl ion concentration arrangement. WQI of most of these samples is good. Undesirable concentrations of arsenic and ammonia are indications of direct infiltration from septic tanks and/or seepage from the drains. Finally, water treatment should be done before usage of groundwater from under the Nile Delta villages because of human-induced contamination.

One hundred sixty-nine groundwater samples were collected, chemically analyzed, and classified into shallow, intermediate, and deep zones to evaluate the vertical and lateral change in groundwater quality in the central part of the middle Nile Delta. To estimate the groundwater suitability for drinking, parameter’s concentrations were evaluated according to WHO drinking water guidelines to delineate the samples of desirable and undesirable range in every zone. According to the computed WQI, most part of the shallow groundwater is unsuitable for drinking [unfit (8 wells, 14.55%), very poor (3 wells, 5.45%), and poor drinking quality (26 wells, 47.3%)]. Intermediate groundwater zone is mostly suitable [excellent (4 wells, 8.9%) and good (24 wells, 53.3%)]. The deep groundwater quality is classified into unfit (3 wells, 4%), very poor (5 wells, 7%), poor water (27 wells, 40%), good quality (30 wells, 45%), and excellent (2 wells, 3%).

Groundwater suitability was also evaluated using TDS, Na%, SAR, RSC, Cl, KI, PI, MH, CAI, and CR. Irrigation water quality index (IQW) was also used as an integrated method. The studied groundwater is mostly of medium suitability where a number of samples which fall within this class are 36 (65.5%), 29 (64%), and 34 (51%) for the shallow, intermediate, and deep groundwater. Water samples have good irrigation quality which increases downward where 15 (27.2%), 13 (29%), and 32 (48%) samples are recorded in this class, respectively. Samples belonging to the poor quality class are mostly located in the northern part, and its sample numbers are 4 (7.3%), 3 (7%), and 1 (1%), respectively.

Due to the progressive increase in land reclamation projects in Egypt, especially east on Nile Delta, efficient water resources management plans and accurate land cover maps are highly vital. In this chapter, the hydrogeological characteristics of the Quaternary groundwater aquifer east of the Nile Delta are presented. This description includes the geomorphology, lithostratigraphy, geological Structure, surface hydrogeology, and the recharge and discharge of the aquifer. The change in land use maps between 1990 and 2004 shows a significant increase in land reclamation which is critical for informing efficient and sustainable policies for groundwater management. MODFLOW software was used to model groundwater flow in three dimensions based on integration with ArcGIS dataset. The stratigraphy of the aquifer was mapped using the solids approach. The groundwater head distribution was calculated in 1990 and between 1990 and 2004 after model calibration for steady and transient states, respectively. The land use for the year 2004 was used to run the predictive transient model to simulate the groundwater flow and budget analysis for the upcoming 8 years (until 2025). Budget analysis results showed that Ismailia Canal and Damietta Branch are the primary recharge components of the aquifer, while the production wells are the main discharge element. Different strategies for well operation can be implemented to control the withdrawal based on the storage capacity and aquifer yield as well as the rising water table in the low elevated lands.

Egypt is considered an arid country and the primary water resource is the River Nile. The limited availability of renewable freshwater for agriculture and urban development is a major constraint. The role of groundwater is steadily increasing and will cover 20% of the total water supply in the coming decades especially in the reclaimed areas of the Western Nile Delta. Serious environmental problems are emerging in the groundwater aquifer in Western Nile Delta such as waterlogging, soil salinity, and the risk of saline water intrusion to the north aquifer. An efficient integrated and sustainable management plan for groundwater resources is needed to avoid the deterioration of the groundwater aquifer in Western Nile Delta. In this chapter, a brief description of the groundwater aquifer in Western Nile Delta and a review of previous studies on groundwater hydrology were presented. GIS and MODFLOW models were integrated to simulate the groundwater flow in the studied Quaternary aquifer. The developed model was calibrated for steady-state and transient conditions for groundwater heads till 2002. The groundwater potentiality was evaluated, and different management scenarios were analyzed for groundwater prediction. The results of the current situation of groundwater showed that groundwater aquifer in Western Nile Delta is susceptible to significant water table reduction especially in the unconfined parts for the case of overstress discharge. The net aquifer recharge was increased for the case of reducing the surface water inflow while increasing the annual abstraction and improving the irrigation system. The annual aquifer potentiality was increased by the construction of a new canal to feed the aquifer towards the northwest direction. Therefore, efficient integrated and sustainable management of groundwater resources relies on a comprehensive database that represents the characteristics of the aquifer and modeling software to achieve the impacts of decision alternatives.

The current Egyptian situation is framed by land and water scarcity, which are under severe stress. The Nile Delta is well known as one of the most densely populated deltas in the world. On the one hand, soil and water resources are at the center of sustainable development and are critical for socioeconomic development. On the other hand, groundwater is considered the second main source of water supply in Egypt after the Nile River, although it represents less than 3% of the total water supply. The Nile Delta aquifer is among the largest underground freshwater reservoirs in the world, and it has been extensively utilized and conjunctively used with the Nile water to cope with the increased demands due to implementing economic development plan in Egypt. The major challenge facing the Nile Delta aquifer is it receives its water (recharging) from the Nile River which is threatened nowadays by the construction and most probably the improper operation of the GERD particularly over the long term. This chapter encapsulates the key groundwater sustainability (in terms of conclusions and recommendations) of the existing main agri-food system and presents insights derived from the cases in the volume. Also, some (update) findings from a few recently published research related to the sustainability covered themes. This chapter presents the main current challenges facing the groundwater aquifer with the set of recommendation to protect the Nile Delta aquifer to its sustainability to supply water to the Nile Delta populations and farmers.