Khafagy, M. M., M. A. Abd-Elmegeed, and A. E. Hassan, "Simulation of reactive transport in fractured geologic media using random-walk particle tracking method", Arabian Journal of Geosciences, vol. 13, issue 34 , 2020.
Hedia, A. M., M. A. Abd-Elmegeed, and A. E. Hassan, Using particle tracking to simulate contaminant transport in the presence of colloids and bacteria, , vol. 14, issue 19, pp. 2024, 2021. AbstractWebsite

The presence of colloids and bacteria in groundwater affects contaminant migration either by facilitation or retardation. The co-transport of contaminant and colloidal particles had been simulated using various finite difference schemes which may suffer from the known and common numerical dispersion problem. In this study, a random walk particle tracking (RWPT) scheme is developed to simulate the co-transport of contaminants, colloids, and bacteria in porous media. Processes modeled include colloidal deposition to and release from solid matrix, bacterial attachment to and detachment from solid matrix, and contaminant sorption onto and desorption from mobile and immobile colloidal particles and bacterial cells as well as solid matrix. Also, the biological processes between contaminant and bacterial cells including bacterial growth, decay, and contaminant utilization are simulated. The developed model is verified against MT3D-MS for reactive contaminant transport with solid matrix, and reaction processes have been verified with solution of a developed analytical solution of mass balance equations. The biological processes are incorporated into the developed RWPT model which is verified against TVD finite difference model developed by (El-Kordy 2008). The results show good performance of RWPT technique in simulating contaminant transport in the presence of colloids and bacteria. The effects of various physical and biological parameters on contaminant transport are investigated. The results show that at least 50,000 particles are required to simulate each constituent mass in case of consideration of biological processes in contaminant transport simulation. On the other hand, 10,000 particles are found to be sufficient to simulate each constituent mass for case of contaminant transport undergoing physical and chemical processes only. The results indicate that contaminant utilization increases by increasing the ratio of initial concentrations of bacterial cells and contaminant, the ratio of the half-saturation constant to initial contaminant concentration, and the ratio of the maximum growth rate to the yield coefficient. It is also found from the results that higher contaminant utilization occurs at early time and decreases as time progresses.

El-Kharakany, M. M., M. A. Abd-Elmegeed, and A. E. Hassan, Modeling radial groundwater flow in fractured media using fracture continuum approach, , vol. 15, issue 4, pp. 354, 2022. AbstractWebsite

Two modeling approaches are commonly utilized for simulating flow in fractured formations: the discrete fracture network (DFN) approach and the stochastic continuum (SC) approach. Although the DFN approach is the most accurate, it has computational and memory constraints. The SC approach ensures fast processing but results in system over-homogenization. The fracture continuum (FC) approach arises as an integrated technique that incorporates the merits of both approaches. The main objective of this research is to develop a computationally efficient technique based on the FC approach to simulate the radial groundwater flow towards wells through two-dimensional fractured media under both steady and transient conditions. A stochastic generation of the DFN is performed in a Monte Carlo framework taking into account wells positioning. The DFN flow system is solved by applying the mass balance equation at fracture intersections. Fracture segments are mapped onto grids of 1 × 1 m and 5 × 5 m resolution as conductivity and specific storage cells. The grid flow problem is solved via MODFLOW. Flow and head discrepancies between the proposed technique and the DFN approach (reference solution) are assessed in steady and transient conditions. A grid-conductivity correction is needed to preserve the DFN flow in the presence of wells. A porosity estimation is proposed to identify the grid-pressure transient response. Promising flow and head results are observed for fine and coarse grid models. Some of the studied cases show large discrepancies in the maximum drawdown obtained on the coarse grid model. Accordingly, a new technique is proposed to handle such discrepancies and is found efficient in transient simulations (e.g., 11% and 26.12% discrepancies are minimized to − 0.93% and − 1.03% for two studied cases). The adopted mapping technique is found efficient when the interest is to estimate the average drawdown over an aquifer as correlation coefficients of 0.89 and 0.97 are found for the coarse and fine grid models, respectively when compared to the DFN model. However, the technique has limitations in estimating the drawdown at locations of wells.

Ibrahim, H. A., M. A. Abd-Elmegeed, A. M. Ghanem, and A. E. Hassan, Assessment of groundwater development potential in Upper Cretaceous aquifer in Sinai, Egypt, , vol. 14, issue 19, pp. 2058, 2021. AbstractWebsite

Regular assessment of groundwater potential is vital especially in arid regions that depend mainly on groundwater. Sinai Peninsula is one of the strategic arid regions in Egypt where any future development plans would mainly depend on groundwater. In this research, the sustainability of the Upper Cretaceous Aquifer in Sinai is evaluated considering the effect of three types of abstractions. First, 54 currently working abstraction wells with total extraction of about 300 m3/day. Second, 24 newly drilled wells that serve 2000 feddan in a new developmental settlement to the west of the study area with expected total extraction of 23,000 m3/day. The third component is the current abstraction of about 20 Mm3/year from the El-Naqb area.. The objective of this study was achieved by analyzing the available geological, lithological, and hydrogeological data and then using these analyzed data to simulate the aquifer using MODFLOW code in the GMS software. The constructed model was calibrated in a transient mode with the aid of parameter estimation program (PEST). A forward run then took place to predict water levels after 30 years considering a new developmental settlement constructed in El-Nehayat (Ras Sudr). Results show that the estimated spatial maximum and average drawdown rates at El-Nehayat are 2.57 and 0.4 m/year which are small values due to the limited present development on the UCA. Based on the obtained results, further exploration for the UCA is recommended.

Ahmed, M. I., M. A. Abd-Elmgeed, and A. E. Hassan, "Modelling transport in fractured media using the fracture continuum approach", Arabian Journal of Geosciences, vol. 12, issue 5, 2019.
Nasr, A. A., M. A. Abd-Elmgeed, and A. E. Hassan, "USING POWER AVERAGING TECHNIQUE TO UPSCALE CONTAMINANT TRANSPORT IN HETROGENEOUS POROUS MEDIA", Journal of Engineering and Applied Science - Faculty of Engineering - Cairo University , vol. 65, issue 4, pp. 283-305, 2018.
Ahmed, S. S., M. A. Abd-Elmgeed, and A. W. Abd-Eldayem, "NONLINEAR CROPPING PATTERN OPTIMIZATION IN EGYPT UNDER DIFFERENT RELEASE SCENARIOS FROM HIGH ASWAN DAM", Journal of Engineering and Applied Science - Faculty of Engineering - Cairo University , vol. 64, issue 6, pp. 443-463, 2018.
Bekhit, H. M., A. E. Hassan, and M. A. Abd-Elmegeed, "Effects of Urban Development, Limestone Dissolution and Preventive Mechanisms on the Groundwater Levels at the Sphinx Archaeological Area, Egypt", The 6th International Groundwater Symposium, International Association for Hydro-Environment Engineering and Research (IAHR), KISR, Kuwait, 19-21 November, 2012.
Abd-Elmegeed, M. A., H. M. Bekhit, and A. E. Hassan, "Stochastic Modeling of Conservative Transport in dual Porosity Media using Finite Cell Method", The 6th International Groundwater Symposium, International Association for Hydro-Environment Engineering and Research (IAHR), KISR, Kuwait, 19-21 November, 2012.
Yosri, A. M., M. A. Abd-Elmegeed, and A. E. Hassan, "Assessing Groundwater Storage Changes in the Nubian Aquifer Using GRACE Data", Arabian Journal of Geosciences , vol. 9, issue 10, 2016.
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