Watershed morphometric analysis of Wadi Baish Dam catchment area using integrated GIS-based approach

The integration of Remote Sensing (RS) and Geographic Information Systems (GIS) constitutes a powerful tool for the evaluation of watershed morphometric parameters. The benefits of this integration include saving time and effort as well as improving the accuracy of the analysis. Moreover, this technique is appropriate for describing the watershed and its streams. In this study, a detailed morphometric analysis of the Wadi Baish catchment area has been performed using the Shuttle Radar Topography Mission (SRTM). The performed morphometric analysis includes linear, areal, and relief aspects. The results of the morphometric analysis reveal that the catchment can be described as of eighth stream order and consists of an area of 4741.07 km². Additionally, the basin is characterized by a relatively high mean value of bifurcation (4.012), indicative of the scarcity of permeable rocks with high slope in the area. This value of bifurcation ratio is consistent with the high drainage density value of 2.064 km/km² and confirms the impermeability of the subsurface material and mountainous relief. The hypsometric integral of the catchment is 47.4%, and the erosion integral of the catchment is 52.6%, both were indications of a mature catchment area.     

Modeling of limestone aquifer in the western part of the River Nile between Beni Suef and El Minia

A robust classification scheme for partitioning groundwater chemistry into homogeneous groups was an important tool for the characterization of Eocene limestone aquifer. The aquifer locally is composed of chalky limestone with thin clay intercalated (Samalut Fm.), the fissures, the joints, and the fractures are represented the conduits of the aquifer system. The flow patterns are conditioned by karstification processes which develop a conduit network and preserve low permeability microfractured blocks. The aquifer is mainly recharged by surrounding aquifers and agricultural wastewaters. The groundwater flows in the eastern part (due the Bahr Yossef and River Nile), which is a discharge area rather than a recharge. Twenty-eight groundwater samples was collected from the Eocene limestone aquifer and analyzed for isotopes, major, and trace elements. δD and δ¹⁸O concentrations ranged widely due to geology, infiltration of different surface waters, evaporation, and hydrogeology. The concentration of δD and δ¹⁸O isotopes is depleted in the northern zone of the northern part and western zone of the central and southern part of the study area. They are enriched due the eastern area of the central and southern part of the study area. δD vs. δ¹⁸O delineate the Pleistocene aquifer and has a strong influence than other waters on aquifer hydrogeochemistry. It is confirmed by the AquaChem outputs of the mixing proportions of different water types included in the aquifer system. Cl-δD and Cl-δ¹⁸O relationships indicate the role of evaporation especially due the eastern area of the central and southern part of the study area. This research tests the performance of the many available graphical and statistical methodologies used to classify water samples. R-mode clustering, correlation analysis, and principal component analysis were investigated. All the methods were discussed and compared as to their ability to cluster, ease of use, and ease of interpretation. Nearly most low-salinity waters are in equilibrium to supersaturate with respect to both carbonate minerals, while it is shifted to undersaturate with salinity. The inverse modeling findings clarify that the calcite, gypsum, and anhydrite dissolution increased due the northeastern area, middle zone, and southern corner of the northern, central, and southern part of the study area, respectively. The latter areas also were characterized by the lowest precipitation of the dolomite. Such areas are distinguished by much more enhancement for aquifer permeability and therefore transmissivity. The latter areas can be use as injection zone by fresh water. It can be a triple function; firstly, it recharges the saline Eocene limestone aquifer through the enhancement hydraulic conductivity and dilutes it. Secondly, it enhances much more the aquifer permeability and therefore the transmissivity. The Eocene limestone aquifer can be improved in quality and quantity by using such a model and exploits it as an alternative water resource with Quaternary aquifer and Nile water. Thirdly, it irrigates more areas to increase the income/capita. The dedolomitization represents the main hydrogeochemical process in the aquifer system. The geomedia (limestone, clay, marl, shale, and sand deposits) are in contact with water, therefore, the rock/water interaction, mixing, and ion exchange were estimated by the geochemical evolution of the groundwater systems.     

Katol meteorite shower, Maharashtra: A preliminary study

A meteorite shower occurred in Katol (21° 15′ 30″ N; 78° 35′ 00″ E; at an elevation of 415 m above msl), Nagpur district of Maharashtra state, India on May 22, 2012 between 14:00 to 14:30 hrs (Indian Standard Time) with a presently observed strewn field of ～5.0 sq km area. The event was experienced by the hundreds of inhabitants with a loud noise and fire ball between Akola in the west to Nagpur in the east. The Geological Survey of India has so far collected 27 meteorite pieces with a total weight of 3500 gm. The locations, size, shape and surface features of the individual meteorite pieces have been recorded. Based on their physical properties, mineralogy, mineral chemical mapping and REE chemistry, the Katol meteorites have been classified as olivine-rich H5 type differentiated stony meteorite with reconstituted chondrules. The preliminary evidence suggests the presence of pre-solar grains in Katol meteorite.     

Nature of serpentinization and carbonation of ophiolitic peridotites (Eastern Desert,Egypt): constrains from stable isotopes and whole-rock geochemistry

Serpentinites are widespread in the Arabian-Nubian Shield (ANS) of the Eastern Desert of Egypt and usually enclose a tremendous carbonate alteration. Combined investigation of the stable isotope compositions of both O-H in serpentines and O-C in the whole-rock and the chemistry of the fluid-mobile elements (FMEs) in whole-rock serpentinites from Wadi (W.) Alam, Gabal (G.) El-Maiyit, and W. Atalla (Eastern Desert of Egypt) allowed to better understand the subsequent fluid sources of serpentinization and carbonation, as well as impact of these processes on the geochemistry of protolith ultramafic rocks. δ ¹⁸O values of W. Alam and W. Atalla serpentine minerals are close to the unaltered mantle and propose a lower temperature serpentinization if compared with those of G. El-Maiyit rocks. Moreover, δD values of W. Alam and W. Atalla serpentines (? 94 to ? 65‰) correspond to an igneous source that might be hydrothermal solutions mixed with the seawater in the mid-ocean ridge-arc transition setting. On the other hand, G. El-Maiyit serpentine is more depleted in ¹⁸O (with lower δ ¹⁸O values = 4.08–4.85‰), and its δD values (? 73 to 56 ‰) are most probably caused by an interaction with metamorphic fluids, acquired during on-land emplacement of oceanic peridotites or during burial in fore-arc setting. In addition, the oceanic oxygen isotope composition of most studied ophiolitic serpentinites points to the preservation of the pre-obduction δ ¹⁸O signatures and thus local-scale fluid flow at low water/rock ratios. Serpentinization fluids were CO₂-poor and the carbonation of the serpentinites resulted from infiltration of externally derived fluids. δ ¹⁸O_VSMOW values of carbonates in the studied serpentinites vary between heavier oxygen isotope composition in G. El-Maiyit samples (av. = 25.32‰) to lighter composition in W. Alam samples (av. = 19.43‰). However, δ ¹³C values of all serpentinites point mantle source of carbon. This source might have been evolved in mid-ocean ridge (W. Atalla) and subduction zone (W. Alam and G. El-Maiyit) settings. The studied serpentinites are usually enriched in FMEs, particularly Pb, Sr, Cs, and U. These enrichments were most probably the result of serpentinization and/or carbonation.     

Adsorption of Congo red and crystal violet dyes onto cellulose extracted from Egyptian water hyacinth

Natural Hazards - The present investigation has highlighted the utility of floating aquatic Egyptian hyacinth, which is considered as a significant reason for environmental problems in Nile River,...     

A new record and a new ichnospecies of Arachnostega from the Middle Miocene of Egypt

The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral-rich, Middle Miocene limestone bed in the middle Siwa Escarpment Member (Marmarica Formation) at Siwa Oasis, northern Western Desert of Egypt. These burrowing traces are preserved on the surface of a few internal moulds of bivalves and gastropods. Until now, the ichnogenus Arachnostega included a single ichnospecies, A. gastrochaenae Bertling, 1992. In the material studied herein, two ichnospecies are identified, described, illustrated and compared with other, similar traces. One of these is a new ichnospecies of Arachnostega; this is here named A. siwaensis ichnosp. nov. It is distinguished from A. gastrochaenae in the possession of tunnels that usually branch in a V-pattern; intervals of ramification are longest in the main branch and decrease in second- and third-order branches. Arachnostega traces were produced in a warm, low-energy, shallow-marine (<10?m water depth) environment. Polychaetes are the most likely producers of marine Arachnostega, which are commonly occurred in the same studied bed. This new occurrence is significant in extending the known stratigraphical and geographical ranges of Arachnostega into the Middle Miocene of Egypt.     

Mapping coastal erosion at the Nile Delta western promontory using Landsat imagery

A set of six Landsat satellite images with 5–9 years apart was used in a post-classification analysis to map changes occurred at Rosetta promontory between 1973 and 2008 due to coastal erosion. Spectral information were extracted from two multi-spectral scanner (MSS) images (1973 and 1978), three thematic mapper (TM) images (1984, 1990, and 1999), and one enhanced thematic mapper plus (ETM+) image (2008). To estimate the quantity of land loss in terms of coastal erosion, a supervised classification scheme was applied to each image to highlight only two classes: seawater and land. The area of each class was then estimated from the number of pixels pertaining to this class in every image. In addition, the shoreline position was digitized to address retreat/advance pattern throughout the study period. Results showed that Rosetta promontory had lost 12.29 km² of land between 1973 and 2008 and the shoreline withdrew southward about 3.5 km due to coastal erosion. Most land loss and shoreline retreat occurred between 1973 and 1978 (0.55 km²/year and 132 m/year, respectively). Coastal protection structures were constructed successively at the promontory. These structures have considerably contributed to reduce coastal erosion; however, they promoted downdrift erosion.     

Hydrogeological investigation of an oasis-system aquifer in arid southeastern Morocco by development of a groundwater flow model

Groundwater of the Tafilalet oasis system (TOS) is an important water resource in the lower Ziz and Rheris valleys of arid southeastern Morocco. The unconfined aquifer is exploited for domestic consumption and irrigation. A groundwater flow model was developed to assess the impact of climatic variations and development, including the construction of hydraulic structures, on the hydrodynamic behavior of the aquifer. Numerical simulations were performed by implementing a spatial database within a geographic information system and using the Arc Hydro Groundwater tool with the code MODFLOW-2000. The results of steady-state and transient simulations between 1960 and 2011 show that the water table is at equilibrium between recharge, which is mainly by surface-water infiltration, and discharge by evapotranspiration. After the commissioning of the Hassan Addakhil dam in 1971, hydraulic heads became more sensitive to annual variations than to seasonal variations. Heads are also influenced by recurrent droughts and the highest water-level changes are recorded in irrigated areas. The model provides a way of managing groundwater resources in the TOS. It can be used as a tool to predict the impact of different management plans for the protection of groundwater against overexploitation and deterioration of water quality.