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Dive into the research topics where Antoifi Abdoulhalik is active.

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Featured researches published by Antoifi Abdoulhalik.


Journal of Environmental Management | 2017

The effectiveness of cutoff walls to control saltwater intrusion in multi-layered coastal aquifers: Experimental and numerical study

Antoifi Abdoulhalik; Ashraf Ahmed

The objective of this study was to examine the performance of cutoff walls in controlling saltwater intrusion in stratified heterogeneous coastal aquifers. Numerical and laboratory experiments were completed in laboratory-scale aquifer where the effectiveness of cutoff walls was assessed in three different configurations, including a homogeneous scenario, a stratified aquifer with high K-low K-high K pattern (case HLH) and another stratified aquifer with low K-high K-low K pattern (case LHL). The results show that the cutoff wall was effective in reducing the saltwater wedge in all the investigated cases of layered-aquifers with toe length reduction of up to 43%. The wall exhibited more wedge reduction in shallower than steeper hydraulic gradients. However, the soil stratification appeared to lessen the overall performance of the wall compared to the homogeneous case. The aquifer stratification disrupted the flow dynamics, and thus affected the freshwater velocity at the wall opening to various degrees, depending on the layering pattern. The presence of an interlayer of low k (case HLH) inhibited the downward movement of the freshwater towards the wall opening, and thus decreasing the repulsion ability of the wall. Moreover, the presence of an underlying low permeability layer (case LHL) was found to obstruct the freshwater flow in the lower part of the aquifer, thereby slowing down the velocity through the wall opening. Numerical analysis of other layering patterns of monotonically increasing/decreasing permeability from top to bottom showed that the cutoff wall remained effective in repulsing the seawater wedge.


Water Resources Management | 2018

Transient Investigation of the Critical Abstraction Rates in Coastal Aquifers: Numerical and Experimental Study

Abdelrahman M. Abdelgawad; Antoifi Abdoulhalik; Ashraf Ahmed; Salissou Moutari; Gerard Hamill

This research investigated the transient saltwater upconing in response to pumping from a well in a laboratory-scale coastal aquifer. Laboratory experiments were completed in a 2D flow tank for a homogeneous aquifer where the time evolution of the saltwater wedge was analysed during the upconing and the receding phase. The SEAWAT code was used for validation purposes and to thereafter examine the sensitivity of the critical pumping rate and the critical time (the time needed for the saltwater to reach the well) to the well design and hydrogeological parameters. Results showed that the critical pumping rate and the critical time were more sensitive to the variations of the well location than the well depth. The critical time increased with increasing the location and depth ratios following a relatively linear equation. For all the configurations tested, the lowest critical pumping rate was found for the lower hydraulic conductivity, which reflects the vulnerability of low permeability aquifers to salinization of pumping wells. In addition, higher saltwater densities led to smaller critical pumping rate and shorter critical time. The influence of the saltwater density on the critical time was more significant for wells located farther away from the initial position of the interface. Moreover, increasing the dispersivity induced negligible effects on the critical pumping rate, but reduced the critical time for a fixed pumping rate.


Hydrological Processes | 2018

Transience of seawater intrusion and retreat in response to incremental water-level variations

Antoifi Abdoulhalik; Ashraf Ahmed

Hydrological Processes. 2018;32:2721–2733. Abstract This paper provides for the first time an experimental study where the impact of sea‐ level fluctuations and inland boundary head‐level variations on freshwater–saltwater interface toe motion and transition zone dynamics was quantitatively analysed under transient conditions. The experiments were conducted in a laboratory flow tank where various (inland and coastal) head changes were imposed to the system and the response of the key seawater intrusion parameters was analysed with high spatial and temporal resolution. Two homogeneous aquifer systems of different grain size were tested. The numerical code SEAWAT was used for the validation. The results show that in cases of sea‐level variations, the intruding wedge required up to twice longer time to reach a new steady‐state condition than the receding wedge, which thereby extend the theory of timescale asymmetry between saltwater intrusion and retreat processes in scenarios involving sea‐level fluctuations. The intruding and receding rates of the saltwater wedge were respectively similar in the scenario involving sea‐level and the freshwater‐level changes, despite change in transmissivity. The results show that, during the intrusion phase, the transition zone remains relatively insensitive, regardless of where the boundary head change occurs (i.e., freshwater drop or sea‐level rise) or its magnitude. By contrast, a substantial widening of the transition zone was observed during the receding phase, with almost similar amplitude in the scenario involving a rise of the freshwater level compared with that caused by a drop of the saltwater level, provided that an equivalent absolute head change magnitude was used. This transition zone widening (occurring during saltwater retreat) was greater and extended over longer period in the low hydraulic conductivity aquifer, for both freshwater‐level rise and sea‐level drop scenarios. The concentration maps revealed that the widening mechanism was also enhanced by the presence of some freshwater sliding and into the wedge during saltwater retreat, which was thereafter sucked upward towards the interface because of density difference effects.


Journal of Hydrology | 2017

A new physical barrier system for seawater intrusion control

Antoifi Abdoulhalik; Ashraf Ahmed; Gerard Hamill


Journal of Hydrology | 2017

How does layered heterogeneity affect the ability of subsurface dams to clean up coastal aquifers contaminated with seawater intrusion

Antoifi Abdoulhalik; Ashraf Ahmed


Estuarine Coastal and Shelf Science | 2018

Transient investigation of saltwater upconing in laboratory-scale coastal aquifer

Antoifi Abdoulhalik; Ashraf Ahmed


World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering | 2017

The Effect of Subsurface Dam on Saltwater Intrusion in Heterogeneous Coastal Aquifers

Antoifi Abdoulhalik; Ashraf Ahmed


World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering | 2017

Transient Freshwater-saltwater Transition-zone Dynamics in Heterogeneous Coastal Aquifers

Antoifi Abdoulhalik; Ashraf Ahmed


24th Salt Water Intrusion Meeting and the 4th Asia-Pacific Coastal Aquifer Management Meeting, Cairns, Australia, July 4-8, 2016. | 2016

Transient analysis of saltwater intrusion dynamic

Antoifi Abdoulhalik; Ashraf Ahmed


24th Salt Water Intrusion Meeting and the 4th Asia-Pacific Coastal Aquifer Management Meeting, Cairns, Australia, July 2016. | 2016

The effect of cutoff walls on saltwater intrusion in stratified coastal aquifers: Experimental and Numerical stud

Ashraf Ahmed; Antoifi Abdoulhalik; Robert Gantley

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Ashraf Ahmed

Queen's University Belfast

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Gerard Hamill

Queen's University Belfast

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Gareth Robinson

Queen's University Belfast

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Salissou Moutari

Queen's University Belfast

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Abdelrahman M. Abdelgawad

Applied Science Private University

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