Groundwater resource sustainability in the Wadi Watir delta, Gulf of Aqaba, Sinai, Egypt

The Wadi Watir delta, in the arid Sinai Peninsula, Egypt, contains an alluvial aquifer underlain by impermeable Precambrian basement rock. The scarcity of rainfall during the last decade, combined with high pumping rates, resulted in degradation of water quality in the main supply wells along the mountain front, which has resulted in reduced groundwater pumping. Additionally, seawater intrusion along the coast has increased salinity in some wells. A three-dimensional (3D) groundwater flow model (MODFLOW) was calibrated using groundwater-level changes and pumping rates from 1982 to 2009; the groundwater recharge rate was estimated to be 1.58?×?10⁶ m³/year. A variable-density flow model (SEAWAT) was used to evaluate seawater intrusion for different pumping rates and well-field locations. Water chemistry and stable isotope data were used to calculate seawater mixing with groundwater along the coast. Geochemical modeling (NETPATH) determined the sources and mixing of different groundwaters from the mountainous recharge areas and within the delta aquifers; results showed that the groundwater salinity is controlled by dissolution of minerals and salts in the aquifers along flow paths and mixing of chemically different waters, including upwelling of saline groundwater and seawater intrusion. Future groundwater pumping must be closely monitored to limit these effects.     

Faster 2-D representation of geotechnical characteristics using MASW method

This paper presents how faster two dimensional (2-D) tomography of soil layers is obtained in geotechnical characteristics through multi-channel analysis of surface wave (MASW) method. MASW is developed as a new technique incorporating multiple receivers and 2-D wave-field transformations to obtain better performance in surface wave analysis. Incorporating 2-D tomography technique with multi-channel analysis offers an efficient and cost effective technique in soil site investigations. In the previous research, the Geo-SW@T software was designed and developed with collecting a lot of records including programming array technique to show the 2-D tomography in near surface soil profiling. To make a 2-D tomography of soil profile based on the past planned MASW technique is time consuming for collecting large database through 2-D array of programming language. In this paper, a new idea is established to obtain faster performance in soil tomography profile using array and sub-array technique in MASW. The performance of newly developed tomography technique with MASW method is estimated as faster and important tomography system for using one single record in soil characterizations rather than arranging of multiple records.     

Groundwater resources assessment for irrigable agricultural lands in the Wadi Araba area, southern Jordan

The main target of this research paper was to the hydrogeological assessment of the groundwater resources to irrigate 600 ha of irrigable agricultural lands, distributed along the Dead Sea–Aqaba Highway in Umm, Methla, Wadi Musa, Qa’ Saideen and Rahma, southern Jordan. Therefore, a comprehensive groundwater study was commenced by drilling eight new wells which can be used to supply irrigable areas with the existing groundwater that would be enriched by the yield of three proposed recharge dams on Wadi Musa, Wadi Abu-Burqa, and Wadi Rahma. The evaluation of the pumping test data of the drilled was carried out using the standard methods of pumping test interpretation. This was based on the available water table measurements at well locations and knowledge of water flow in the general. The sustainable yield of each well was calculated based on the pumping test parameters. The obtained results indicate that pumping out of Beer Mathkor wells should not exceed 1,100 m³/day in the case of continuous pumping and 8,700 m³/day in the case of intermittent pumping. Since the water table did not significantly change with small changes in pumping (it took eightfolds of magnitude increase in pumping from approximately 1,100 to 8,700 m³/day to show a significant drop in the water table equivalent to about 5.5 MCM per year from the aquifer.     

Acoustic evidence for shallow gas accumulations in the sediments of the Eastern Black Sea*

ABSTRACT The Black Sea contains immense gas accumulations. Exploration of gas accumulations is geologically and economically important because migration of methane in sediments may cause massive slope failures and the methane seeps may indicate deeper hydrocarbon reservoirs. Human activity both in and on the seafloor (oil industry) and natural activity (earthquakes, cyclones) trigger mechanisms for seafloor failure and gas release that may have a local and possibly global environmental impact. Recently, sonar and high‐resolution seismic surveys were carried out to obtain information about the effects of gas and gas‐filled sediments throughout the Turkish margin of the Eastern Black Sea, and shallow gas was detected on the subbottom profiler records. It continues about 25–65 m below the sea floor and is marked by bright and cloudy spots, sometimes pockmarks and acoustic voids. The lower section of the Turkish shelf is an extensive pockmarked plateau. The pockmarks are seen as circular structures with high backscattering on the sonar records.     

Modelling strain localization in granular materials using micropolar theory: numerical implementation and verification

Implementation and applications for a constitutive numerical model on F‐75 silica sand, course silica sand and two sizes of glass beads compressed under plane strain conditions are presented in this work. The numerical model is used to predict the stress versus axial strain and volumetric strain versus axial strain relationships of those materials; moreover, comparisons between measured and predicted shear band thickness and inclination angles are discussed and the numerical results compare well with the experimental measurements. The numerical model is found to respond to the changes in confining pressure and the initial relative density of a given granular material. The mean particle size is used as an internal length scale. Increasing the confining pressure and the initial density is found to decrease the shear band thickness and increase the inclination angle. The micropolar or Cosserat theory is found to be effective in capturing strain localization in granular materials. The finite element formulations and the solution method for the boundary value problem in the updated Lagrangian frame (UP) are discussed in the companion paper. Copyright © 2006 John Wiley & Sons, Ltd.     

Modelling strain localization in granular materials using micropolar theory: mathematical formulations

It has been known that classical continuum mechanics laws fail to describe strain localization in granular materials due to the mathematical ill‐posedness and mesh dependency. Therefore, a non‐local theory with internal length scales is needed to overcome such problems. The micropolar and high‐order gradient theories can be considered as good examples to characterize the strain localization in granular materials. The fact that internal length scales are needed requires micromechanical models or laws; however, the classical constitutive models can be enhanced through the stress invariants to incorporate the Micropolar effects. In this paper, Lade's single hardening model is enhanced to account for the couple stress and Cosserat rotation and the internal length scales are incorporated accordingly. The enhanced Lade's model and its material properties are discussed in detail; then the finite element formulations in the Updated Lagrangian Frame (UL) are used. The finite element formulations were implemented into a user element subroutine for ABAQUS (UEL) and the solution method is discussed in the companion paper. The model was found to predict the strain localization in granular materials with low dependency on the finite element mesh size. The shear band was found to reflect on a certain angle when it hit a rigid boundary. Applications for the model on plane strain specimens tested in the laboratory are discussed in the companion paper. Copyright © 2006 John Wiley & Sons, Ltd.     

Energy-Momentum of a Stationary Beam of Light in Teleparallel Gravity

In this paper, we utilize the teleparallel gravity analogs of the energy and momentum definitions of Bergmann-Thomson and Landau-Lifshitz in order to explicitly evaluate the energy distribution (due to matter and fields including gravity) based on the Bonnor space-time, it is shown that for a stationary beam of light, these energy-momentum definitions give the same result. Furthermore, this result supports the viewpoint of Cooperstock and also agree with the previous works by Bringley and Gad.     

Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions

The present study reports the synthesis of a novel ionophore, calix[4]azacrown ( 5 ) bearing two amino groups at the lower rim along with its oligomeric analogue ( 6 ). The liquid‐liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that ( 5 ) and ( 6 ) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species ( 5 ) shows remarkable extraction properties at low pH, whereas species ( 6 ) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants.     

Formation of the Upper Pleistocene terraces of Lake Van (Turkey)

Sedimentological and geomorphological studies of terraces around Lake Van (1647 m) provided a preliminary framework for lake‐level variations. The elevations of terraces and past lake level were measured with a differential global positioning system. A chronology is developed using ²³⁴U/²³⁰Th dating of travertines, ³⁹Ar/⁴⁰Ar dating of pyroclastites and ¹⁴C dating of organic matter. Facies and stratigraphic correlations identify four transgressions (C1′, C1″, C2′ and C2″), each followed by a regression which ended with low lake levels that caused river incision and terrace formation. Evidence of the oldest transgression (C1′) is found in the uppermost reaches of valleys up to 1755 m, an altitude higher than the present lake threshold (1736 m). This C1′ transgression may be related to pyroclastic flows which dammed an outlet located in the western part of the lake basin and which is dated to before 105 ka. After 100 ka, a second transgression (C1″) reached 1730/1735 m, possibly related to a younger ignimbrite flow, in association with high water inflow (warm and/or wetter conditions). The two younger transgressions reached 1700–1705 m. The first one (C2′) is dated to 26–24.5 cal. ka BP and the second one (C2″) to 21–20 cal. ka BP. Available data suggest that the long‐term lake‐level changes responded mainly to climate oscillations. Additional events such as river captures caused by volcanic falls filling valleys, tectonism, erosion and karstic diversion may have impacted these long‐term lake‐level changes. Copyright © 2010 John Wiley & Sons, Ltd.