Groundwater resources in coastal aquifers constitute a main source of freshwater in many regions around the globe. This is typically true in arid and semi-arid regions where rainfall is scarce and infrequent and the surface water resources are almost absent. The consequences of climate changes and global warming on the freshwater in coastal aquifers have been investigated by several researchers over the last two decades. Due to the expected increase in the global temperature and the associated expansion of water in

Understanding of the continuous dynamic relationship between water availability and land use /land cover change (LUCC) is an essential step in urban development planning. This is particularly crucial in dryland environments, where water and fertile soil are very limited and nonrenewable. Dakhla Oasis is located in the heart of the Western Desert of Egypt, 190 km to the west of Kharga Oasis, and is the oasis furthest from the main settlements of Egypt. Dakhla Oasis contains highly fertile lands and is rich in groundwater. It supports a relatively high population compared to Kharga Oasis with about 100,000 inhabitants. Groundwater is the only water source for irrigation and domestic use. The economy of Dakhla depends on several industries including agriculture, handicrafts and tourism. This paper presents the main results of an interdisciplinary research project in Dakhla Oasis with special emphasis on Rashda Village within the Oasis. The study is a model investigation of groundwater resources, land use/land cover and their link with demographic characteristics. One 1972 Landsat Multispectral Scanner System image, two 1984 Landsat Thematic Mapper images and Six 2011 SPOT4 satellite images were used for LUCC detection. In addition, a detailed database of groundwater extraction from 1960 to 2005 was available. Supervised image classification and visual interpretation were integrated to achieve more accurate LUCC maps. The results show that the study area has undergone very severe land cover changes with significant increases in urban settlements and in agricultural land. Local aquifer recharge and recovery fails to compensate for artificial groundwater extraction. The overall discharge increased between 1976 and 2006 by 54% to 62%, in different areas. This was associated with increases in population ranging from 8.5% to 150% in the same period. If extraction continues at current rates, pumping with current technology will become uneconomical in the next 90 years.

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Erosion hotspots within a drainage basin refer to an area that erodes more rapidly than anticipated or more rapidly than adjacent portions. Or, areas having high erosion rate as compared to the adjacent places. Since erosion can adversely affect ecosystems on-site as well as off-site, the estimation of runoff and soil loss in catchments is becoming more important. The main objective of this work is to: (1) delineate the hotspot areas (areas of erosion/sediment source) within the Abbay/Blue Nile Basin, (2) generate vulnerability maps to assess the risk possibilities at these areas as well as to support the watershed management approaches for the whole basin, (3) determine the environmental impact, and (4) evaluate sediment and water resources. The area under consideration is located to the northwestern of Ethiopia and to the East of Sudan, directly on the political boundary separating the two countries. The basin area is about 314458 km² and is fully dissected by streams that form the Blue Nile River. The majority of mentioned area is considered one of the most important highlands feeding the River Nile with both water and sediment. Therefore, Assessment of the erosion hotspots within this basin is essential for the management of the whole system. The Splash and sheet erosion are most widely observed within the highlands of the Blue Nile basin in Ethiopia, which generate noticeable amounts of sediments that induce and increase the erosion rate when the rills and gullies start to form. The slope, runoff intensity, and soil types are the most factors that play an essential rule in the erosion hotspots. The Digital Elevation Model (DEM) was used to derive the slope angels, shapes (concavity and convexity), profile curvature, as well as the flow direction vector. Approximately 65% of the area has a slope gradient less than 15%. However, very steep slopes (up to 65%) are also present, increasing the risk of erosion in these mountainous areas. Climate maps, runoff maps, soil maps, land use maps as well as satellite images were also used in the spatial calculations and modeling. For the modeling phase, the Water Erosion Prediction Project (WEPP) Model along with the Geo-Spatial Interface for WEPP (GeoWEPP), integrated with the GIS, were used. The potential reading of the resulted maps showed that the most affected areas with erosion lie within the highlands of Ethiopia where there are very steep slopes, soft soil cover, and intensive runoff. Also, down from the highlands in Sudan, there are several hotspots formed due to the erosion by mass movement which due to the existence of specific soil types.

Past discussions around water-resources management and development in the River Nile basin disregard groundwater resources from the equation. There is an increasing interest around factoring the groundwater resources as an integral part of the Nile Basin water resources. This is hampered by knowledge gap regarding the groundwater resources dynamics (recharge, storage, flow, quality, surface-water/groundwater interaction) at basin scale. This report provides a comprehensive analysis of the state of surface-water/groundwater interaction from the headwater to the Nile Delta region. Piezometric and isotopic(δ18O,δ2H) evidence reveal that the Nile changes from a gaining stream in the headwater regions to mostly a loosing stream in the arid lowlands of Sudan and Egypt. Specific zones of Nile water leakage to the adjacent aquifers is mapped using the two sources of evidence. Up to 50% of the surface-water flow in the equatorial region of the Nile comes from groundwater as base flow. The evidence also shows that the natural direction and rate of surface-water/groundwater interaction is largely perturbed by human activities (diversion, dam construction) particularly downstream of he Aswan High Dam in Egypt. The decrease in discharge of the Nile River along its course is attributed to leakage to the aquifers as well as to evaporative water loss from the river channel. The surface-water/groundwater interaction occurring along the Nile River and its sensitivity to infrastructure development calls for management strategies that account groundwater as an integral part of the Nile Basin resources.

The generation and processes of wadi flash floods are very complex and are not well understood. In this paper, we investigate the relationship between variations in geomorphometric and rainfall characteristics and the responses of wadi flash floods. An integrated approach was developed based on geomorphometric analysis and hydrological modeling. The Wadi Qena, which is located in the Eastern Desert of Egypt, was selected to validate the developed approach and was divided into 14 sub-basins with areas ranging from 315 to 1488 km2. The distributed Hydrological River Basin Environment Assessment Model (Hydro-BEAM) was used to obtain a good representation of the spatial variability of the rainfall and geomorphology in the basin. Thirty-eight geomorphometric parameters representing the topographic, scale, shape and drainage characteristics of the basins were considered and extracted using geographic information system (GIS) techniques. A series of flash flood events from 1994, 2010, 2013, and 2014, in addition to synthetic virtual storms with different durations and intensities, were selected for the application of this study. The results exhibit strong correlations between scale and topographic parameters and the hydrological indices of the wadi flash floods, while the shape and drainage network metrics have smaller impacts. The total rainfall amount and duration significantly impact the relationship between the hydrologic response of the wadi and its geomorphometry. For most of the parameters, we found that the impact of the wadi geomorphometry on the hydrologic response increases with increasing rainfall intensity.

The generation and processes of wadi flash floods are very complex and are not well understood. In this paper, we investigate the relationship between variations in geomorphometric and rainfall characteristics and the responses of wadi flash floods. An integrated approach was developed based on geomorphometric analysis and hydrological modeling. The Wadi Qena, which is located in the Eastern Desert of Egypt, was selected to validate the developed approach and was divided into 14 sub-basins with areas ranging from 315 to 1488 km2. The distributed Hydrological River Basin Environment Assessment Model (Hydro-BEAM) was used to obtain a good representation of the spatial variability of the rainfall and geomorphology in the basin. Thirty-eight geomorphometric parameters representing the topographic, scale, shape and drainage characteristics of the basins were considered and extracted using geographic information system (GIS) techniques. A series of flash flood events from 1994, 2010, 2013, and 2014, in addition to synthetic virtual storms with different durations and intensities, were selected for the application of this study. The results exhibit strong correlations between scale and topographic parameters and the hydrological indices of the wadi flash floods, while the shape and drainage network metrics have smaller impacts. The total rainfall amount and duration significantly impact the relationship between the hydrologic response of the wadi and its geomorphometry. For most of the parameters, we found that the impact of the wadi geomorphometry on the hydrologic response increases with increasing rainfall intensity.

The generation and processes of wadi flash floods are very complex and are not well understood. In this paper, we investigate the relationship between variations in geomorphometric and rainfall characteristics and the responses of wadi flash floods. An integrated approach was developed based on geomorphometric analysis and hydrological modeling. The Wadi Qena, which is located in the Eastern Desert of Egypt, was selected to validate the developed approach and was divided into 14 sub-basins with areas ranging from 315 to 1488 km2. The distributed Hydrological River Basin Environment Assessment Model (Hydro-BEAM) was used to obtain a good representation of the spatial variability of the rainfall and geomorphology in the basin. Thirty-eight geomorphometric parameters representing the topographic, scale, shape and drainage characteristics of the basins were considered and extracted using geographic information system (GIS) techniques. A series of flash flood events from 1994, 2010, 2013, and 2014, in addition to synthetic virtual storms with different durations and intensities, were selected for the application of this study. The results exhibit strong correlations between scale and topographic parameters and the hydrological indices of the wadi flash floods, while the shape and drainage network metrics have smaller impacts. The total rainfall amount and duration significantly impact the relationship between the hydrologic response of the wadi and its geomorphometry. For most of the parameters, we found that the impact of the wadi geomorphometry on the hydrologic response increases with increasing rainfall intensity.

In arid regions, people strive to have high drinking water quality resource. Limited water resources in arid regions present a critical factor that affects economic and societal development. The hydrogeological and hydrological conditions in such areas are extreme variable and affect largely the hydrochemical characteristics of the groundwater system. This study was carried out in Elhasya (Edfu, Aswan, Egypt) with an objective of understanding the suitability of local groundwater quality for domestic purposes in such arid climate region and to investigate the potential impact of untreated sewage discharges and irrigation canals on groundwater quality. In order to accomplish these targets, 250 water samples were collected from 4 groundwater wells and analyzed for physical, chemical and biological parameters in the period from Jan. 2007 to Dec. 2012. The hydrological characteristics of the region have been identified. Aquachem tool was used to define and characterize the hydrchemistry of the pumped water samples. Wells can be considered neutral to slightly alkaline, pH is around (6.5-8.5). Cations (Mg2+, Na+ and Ca2+) and anions (HCO3–, Cl–, and SO42–) were measured using ion chromatography instrument and it was clear that they did not exceed the recommended limits of world health organization (WHO) nor the Egyptian standards. However, bacteriological and biological results refer to that the wells are contaminated and a dose of disinfectant should be injected for drinking use. Stiff and piper diagrams were used to evaluate the hydrochemistry of groundwater of the study area. According to the plotting results, we can say that the majority of groundwater samples was characterized by the abundance alkaline earth metals (Ca2+, Mg2+) over of the alkalis (Na+, K+). In conclusion, it is apparent that the pumped water in El-Hasya city needs to be injected with dose of disinfectant to promote the biological activity so as to be suitable for drinking uses.