Mostafa Mohamed

Rainfall-Runoff Modeling of Three Wadis in the Northern Area of UAE

Hydrologic Engineering Center-Hydrologic Modeling System model is used to estimate the water storage in the lakes of three dams due to rainfall events in three wadis located in the northern area of the United Arab Emirates (UAE). Like other arid and semiarid regions, rainfall events in the three wadis are limited, scattered, and random. For model calibration, the simulated results were compared with the observed water storage data for several storm events. A family of rainfall-runoff/storage curves was developed based on the duration and intensity of rainfall events. These curves can be used for prediction of surface water runoff in the three wadis and water storage in the dams in response to different rainfall events. The same rainfall event in wadi Bih generates almost twice as much of the surface water runoff generated in each of wadi Ham and wadi Tawiyean. This is mainly attributed to the large catchment area of wadi Bih as compared to the other two wadis. The sensitivity analysis revealed that the am...

Relationship between geological structures and groundwater flow and groundwater salinity in Al Jaaw Plain, United Arab Emirates; mapping and analysis by means of remote sensing and GIS

Geological structures can be of great influence groundwater movement and accumulation in the surface and subsurface, and should therefore be taken into consideration in studies related to groundwater contamination impact. This study attempts to investigate the influence of geological structures on groundwater flow and groundwater salinity in Al Jaaw Plain, United Arab Emirates. A set of thematic maps derived from digital elevation model (DEM), LANDSAT, and Spaceborn Imagine Radar-C/X-Band Synthetic Aperture Radar were enhanced by applying Soble filter with 10xa0% threshold and equalization enhancement to reveal and map geological structures crosscut the entire region. Drainage pattern was derived from DEM automatically using D8 algorithm. The algorithm determines in which neighboring pixel any water in a central pixel will flow naturally. The trends of geological structures and drainage pattern extracted from remote sensing data were correlated with the spatial variation of hydraulic head, thickness aquifer, and groundwater salinity in the region. The results of the study reveal that the wadi courses, thickness of the aquifer, and topography are structural controlled by NNW–SSE, NE–SW, and ENE–WSW trending fault zones, significantly influencing the groundwater flow and groundwater contamination in Al Jaaw Plain.

Remote sensing and GIS applications of surface and near-surface hydromorphological features in Darfur region, Sudan

Groundwater modelling and mapping in a region partly inaccessible using traditional techniques is practically very difficult, and time and cost consuming. However, integration of remote sensing and GIS enables more reliable mapping and analysis of hydromorphological elements such as palaeolakes. In the present study, a set of automated morphometric techniques of fitting a bivariate quadratic surface in a moving window of size 3 × 3 was used and modified to map and analyse hydromorphological elements in northwestern Sudan. Geomorphometry results indicate that the palaeodrainage network incision and depressions may have received most of the rainwater during late Quaternary wet phases. The results revealed that of the total 2000 km2 coverage of the unnamed depression, about 49.6% was classified as accumulation zone with a recharge area of about 992 km2, while the Wadi Fesh Fesh and Oyo depressions were shown to have the smallest areas of accumulation zone, approximately 31.3% and 37.3%, respectively. Validation of the methods was made by comparing trends and textural features from a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) with 30 m spatial resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM and 0.6 m spatial resolution Quickbird images and geological maps of the study area. The maps obtained showed a strong correlation, indicating that the proposed methods are very efficient tools for regional mapping and analysing hydromorphological elements in arid regions and remote and inaccessible regions.

Probabilistic frequency ratio model for groundwater potential mapping in Al Jaww plain, UAE

The United Arab Emirates, as a part of the Arabian Peninsula, is among the driest countries on earth. This study aims to map and explore new groundwater reservoirs in Al Jaaw Plain, UAE. To map new groundwater reservoirs, a probability frequency ration model was modified. Two sets of remote sensing data were used to generate hydrological, topographical and geological parameters. There are six parameters were chosen based on their level of contribution toward groundwater potentiality. These parameters are lithological unites, lineaments, drainage network, topographic slope, altitude and topographic curvature. Groundwater potentiality was spatially analyzed using groundwater well locations employing the probability frequency ratio model by superimposing groundwater wells over the computed map in GIS. The results shows that the very high potential zones of groundwater are occupied by 96.72xa0km2 (7.46xa0%) of the total area. Hydrological map and groundwater wells locations were used to validate the resultant map. The accuracy of the map was 87.67xa0%. The obtained map can be used in groundwater exportation and land development.

Sensitivity of benzene natural attenuation to variations in kinetic and transport parameters in Liwa aquifer, UAE.

Dissolved benzene was detected in the shallow unconfined Liwa aquifer (UAE). This aquifer represents the main freshwater source for a nearby residence camp area. A finite element model is used to simulate the fate, transport, and attenuation of the dissolved benzene plume to help decision makers assess natural attenuation as a viable remediation option. Sensitivity of benzene attenuation to uncertainties in the estimation of some of the kinetic and transport parameters is studied. It was found that natural attenuation is more sensitive to microbial growth rate and half saturation coefficients of both benzene and oxygen than initial biomass concentration and dispersivity coefficients. Increasing microbial growth rate by fourfold increased natural attenuation effectiveness after 40xa0years by 10%; while decreasing it by fourfold decreased natural attenuation effectiveness by 77%. On the other hand, increasing half saturation coefficient by fourfold decreased natural attenuation effectiveness by 46% in 40xa0years. Decreasing the same parameter fourfold caused natural attenuation effectiveness to increase by 9%.

Automatic Feature Extraction Module for Change Detection in Al Ain, UAE: Analysis by Means of Multi-temporal Remote Sensing Data

Monitoring new changes in cities adjacent to dynamic sand dunes requires precise classifier technique. Unlike traditional techniques of supervised classification which use training sites, the integration of image transformation tasseled cap and automatic feature extraction module based on spectral signatures has provided to be sensitive and realistic techniques with time and cost effective. The proposed module was applied to Al Ain district, United Arab Emirates (UAE). The module consists of four steps in terms of segmentation, thresholding and clustering and computing attributes. The obtained greenness and classified maps were then enhanced by applying a 3u2009×u20093 Sobel filter. The new changes were detected by combining the multi-temporal greenness and classification maps. Accuracy assessment and quantitative analysis were performed using confusion matrix and ground truthing. The results showed significant increasing in urban and agricultural areas from the year from 1990 to 2000 compared with the period of time from the year 2000 to 2006. The image difference showed that the vegetation and building classes had increased 7.58 and 20.28xa0km2 respectively. This study showed that image difference and fuzzy logic approach are the most sensitive techniques for detecting new changes in areas adjacent to dynamic sand dunes.

Groundwater of Abu Dhabi Emirate: a regional assessment by means of remote sensing and geographic information system

Mapping of geological, topographical, and hydrological elements is critical for understanding and assessing the regional hydrological setting in an arid region. In this study, a synergistic approach has been developed, which uses a combination of remote sensing data and geographic information system (GIS) to map factors controlling groundwater recharge, discharge, and quality across the Abu Dhabi Emirate. The Spectral Angel Mapper (SAM) algorithm, which uses a n-D angle to match the pixels to reference spectra, was used to map new water-bearing rocks, and the deterministic eight-node (D8) algorithm, which allows flow to only one of the eight neighbors based on the direction of steepest descent, was used to map paleochannels. The terrain category was applied to simulate seawater intrusion from digital elevation model (DEM). New maps of lithology, normalized difference vegetation index (NDVI), and paleochannels were derived and interpreted from multi-sources of remote sensing data. The study indicated that the area was produced by a fluvial and eolian process and recharged by local, intermediate, and regional flows. The results showed that the Oman and Hafeet Mountains are the natural sources of groundwater recharge as well as HCO3, Ca, Na, and Mg in groundwater. The mapped factors were spatially correlated with hydrologic anomalies observed in groundwater wells. The integrated approach is timely, cost-effective, and can be used in arid regions for numerical modeling as well as water balance analysis.

Hydrochemistry assessment of groundwater quality in Al-Ain city, UAE

Groundwater is the main source for irrigation purposes in Al-Ain city. Urbanization and agricultural activities are considered potential sources of groundwater pollution in this area. Therefore, assessment of groundwater quality is very important to detect and prevent contamination for effective groundwater management. This paper focuses on the impact of urbanization on the groundwater resources of the gravel alluvial aquifer in the vicinity of Al-Ain city (northeast of Abu Dhabi Emirate). Groundwater samples were collected from 28 wells in Al-Ain city. The chemical monitoring revealed high spatial variability in chemical parameters as influenced by climate, matrix aquifer changes in geological formations, and water table depth. Results show that changes in groundwater chemistry in the aquifer are mainly controlled by evaporation, silicate mineral dissolution, evaporite dissolution, cation exchange, and mixing by upward leakage from Jabal Hafit limestone aquifer. The concentration increases were accounted for primarily by dissolved sodium, chloride, and sulfate. The high total dissolved solids (TDS) of shallow groundwater beneath the city of Al-Ain (up to 5640xa0mg/L) are mainly controlled by evaporation. Groundwater quality was better in the northeast and the east areas (near Oman Mountains) compared to the south area (northern edge of Jabal Hafit).

Natural and anthropogenic factors affecting groundwater quality in the eastern region of the United Arab Emirates

Groundwater contamination is a serious health and environmental problem in the eastern region of the United Arab Emirates. Factors affecting groundwater quality are known to be natural and anthropogenic, but the process through which it is being released is poorly understood. In this study, an attempt has been made to map and spatially correlate factors controlling groundwater quality using a combination of remote sensing and geographic information system technology. Factors, which might have spatial relation with groundwater quality, namely flow direction, host rock, land use and topographic slope, were selected as essential factors. Factor thematic maps were extracted from remote sensing data using deterministic eight-node and fuzzy logic algorithms. The obtained maps were correlated with groundwater data collected from groundwater wells. The results show that pollutants resulting from intensive agriculture and human activities and carbonate rocks in the Al Ain area are likely to contribute significantly to the degradation of groundwater quality. The results also show that the salinity in groundwater ranges from 100xa0mg/L at the foot of the Oman Mountain to 5,343xa0mg/L at Al Ain city.

Land use/land cover change impact on groundwater quantity and quality: a case study of Ajman Emirate, the United Arab Emirates, using remote sensing and GIS

Ajman is a rapidly urbanizing emirate with land development succeeding at a fast pace. This study aims to monitor land use/land cover changes and assesses the impact of these changes on groundwater quality and quantity of the shallow aquifer using multitemporal remote sensing data and geographic information system (GIS). To monitor the land use/land cover changes, the Spectral Angle Mapper (SAM) and the Normalized Difference Vegetation Index (NDVI) algorithms were utilized. The obtained maps were correlated against a set of total dissolved solid (TDS); Mg, Cl, and NO3 groundwater quality index; and depth to the groundwater table maps constructed from groundwater data. The spatial analysis revealed a sharp depletion in groundwater quality and quantity related to the increase in the land use/land cover classes. The mean total TDS is from 21,971 to 26,450xa0mg/L and depth to groundwater level from −12.33 to −17.2xa0m over a period of 15xa0years. Maps of normalized difference and groundwater quality sustainability showed that the eastern side of the study area has a high value of groundwater quality sustainability and normalized difference, while the western side of the study area has a minimal value of groundwater quality sustainability and normalized difference. This study is of great assistance for decision makers and land developers to relate to municipal land allotment in rapidly developing regions such as Ajman.