A new approach to study seawater intrusion problems in coastal aquifers is presented. The approach is demonstrated for the case of the Nile Delta aquifer in Egypt. FEFLOW, a 3D finite element variable density model, is employed, however, because of the lack of 3D data, and to demonstrate the proposed approach, the simulations are performed in 2D horizontal views. The concept of equivalent freshwater head (usually implemented in 2D vertical simulations) is adapted in the horizontal (areal) simulations. After calibration against field observations, the simulations are conducted at four horizontal sections located at different levels (100, 200, 300 and 400 m) below the mean seawater level. The depth of the horizontal section is identified through assigning an appropriate pressure ‘‘equivalent freshwater’’ head at the boundaries. The study domain is modified for the horizontal sections at 300 and 400 m, respectively, to account for the aquifer geometry at these depths. The effect of freshwater recharge from the Nile River on the seawater intrusion is observed in the upper layer around its two main branches. The results of the horizontal simulations clearly demonstrate the variation of water concentration in the vertical direction. As the depth increases, the transition zone (in which the concentration varies from the seawater to the freshwater concentration) is shifted toward the landside and become more extensive. At the lower levels of the Nile Delta aquifer, the seawater migrates much further inland as compared to the shallower levels. The concept of horizontal simulations at different levels is further developed to produce meaningful concentration distributions in the vertical sections. This approach allows for a better realization of seawater intrusion in coastal aquifers.

Several investigations have recently considered the possible impacts of climate change and seawater level rise on seawater intrusion in coastal aquifers. All have revealed the severity of the problem and the significance of the landward movement of the dispersion zone under the condition of seawater level rise. Most of the studies did not consider the possible effects of the seawater rise on the inland movement of the shoreline and the associate changes in the boundary conditions at the seaside and the domain geometry. Such effects become more evident in flat, low land, coastal alluvial plans where large areas might be submerged with seawater under a relatively small increase in the seawater level. None of the studies combined the effect of increased groundwater pumping, due to the possible decline in precipitation and shortage in surface water resources, with the expected landward shift of the shore line. In this article, the possible effects of seawater level rise in the Mediterranean Sea on the seawater intrusion problem in the Nile Delta Aquifer are investigated using FEFLOW. The simulations are conducted in horizontal view while considering the effect of the shoreline landward shift using digital elevation models. In addition to the basic run (current conditions), six different scenarios are considered. Scenarios one, two, and three assume a 0.5m seawater rise while the total pumping is reduced by 50%, maintained as per the current conditions and doubled, respectively. Scenarios four, five, and six assume a 1.0m seawater rise and the total pumping is changed as in the first three scenarios. The shoreline is moved to account for the seawater rise and hence the study domain and the seaside boundary are modified accordingly. It is concluded that, large areas in the coastal zone of the Nile Delta will be submerged by seawater and the coast line will shift landward by several kilometers in the eastern and western sides of the Delta. Scenario six represents the worst case under which the volume of freshwater will be reduced to about 513 km3 (billionm3).

A numerical groundwater model of the Nubian Aquifer System was established to prove the influence of rising seawater levels on the groundwater salinity in northern Egypt over the last 140,000years. In addition, the impact of a groundwater recharge scenario for these 140,000years, involving climatic change, on the saltwater/ freshwater interface was investigated. Saltwater intrusion induced by rising water levels of the Mediterranean Sea led to salinisation from the Mediterranean Sea to the Qattara depression. This modeling approach was supported by a density-driven model setup and calculation. The modelled saltwater/freshwater interfaces partially fitted the observed ones, especially in the southern half of the Qattara depression. In other parts of the northern Nubian Aquifer System, the ingression of salt water was modelled adequately, but in the west, small regions of the measured interface were not. The development in the Qattara depression (Egypt) and Sirte basin (Libya) were investigated in more detail. The different behaviour in the Sirte basin may be due to high evapotranspiration rates in some former periods, salt solutions from the pre- Quaternary layers or saltwater infiltration from sabkhalike recent salt-bearing sediments.

Corrosion inhibition of aluminum (Al) in hydrochloric acid by anionic polyeletrolyte pectates (PEC) as a water-soluble natural polymer polysaccharide has been studied using both gasometric and weight loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. The inhibition action of PEC on Al metal surface was found to obey the Freundlich isotherm. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the kinetic results is discussed in the paper.

We have determined the phase transition for the Co-20 and -30 at.% Cu alloys fabricated by arc melting technique, from the binodal to the two phases þL as well as the peritectic transitions, using differential thermal analysis (DTA). We equally studied the effects of aging treatment, ranging from 3 to 35 h, on the alloy samples using scanning electron microscopy (SEM) and Vickers hardness (HV). The activation energies of these alloys are equally determined using five established models. Our results show that for aging time up to 15 h, within the spinodal region at 773 K, the hardness value for Co-20 and -30 at.% Cu alloys oscillates reaching a local maximum at the aging time of 8.50.5 h. After 20 h of heat treatment, the HV for Co-20 at.% Cu alloy diminishes significantly while that of Co-30 at.% Cu effectively stabilizes at 241 MPa. The activation energies for the peritectic transformation based on Ozawa model are estimated to be 2465 and 2680 kJ mol1 for Co-20 and -30 at.% Cu, respectively.

The transmission and reflection spectra of the chalcogenide Te67.5 Ga2.5 As30 thin film with thickness of 150, 300 and 450 nm are measured. The formed crystalline phases due to the thermal annealing of the as-prepared film are identified by X-ray diffraction. The as-prepared films have absorption mechanism which is an indirect allowed transition with a decrease in the value of the optical energy gap (Eg) as the thickness increases. The films annealed at temperatures higher than the temperature of the onset of the crystallization have a direct allowed transition with an increase in Eg with annealing temperatures. The effect of the film thickness on the refractive index and the high-frequency dielectric constant are studied.