Use of Geophysical and Remote Sensing Data for Assessment of Aquifer Depletion and Related Land Deformation     

Abdullah Othman  Mohamed Sultan  Richard Becker  Saleh Alsefry  Talal Alharbi  Esayas Gebremichael  Hassan Alharbi  Karem Abdelmohsen 《Surveys in Geophysics》2018,39(3):543-566

An integrated approach [field, Interferometric Synthetic Aperture Radar (InSAR), hydrogeology, geodesy, and spatial analysis] was adopted to identify the nature, intensity, and spatial distribution of deformational features (sinkholes, fissures, differential settling) reported over fossil aquifers in arid lands, their controlling factors, and possible remedies. The Lower Mega Aquifer System (area 2 × 10⁶ km²) in central and northern Arabia was used as a test site. Findings suggest that excessive groundwater extraction from the fossil aquifer is the main cause of deformation: (1) deformational features correlated spatially and/or temporally with increased agricultural development and groundwater extraction, and with a decline in water levels and groundwater storage (? 3.7 ± 0.6 km³/year); (2) earthquake events (years 1985–2016; magnitude 1–5) are largely (65% of reported earthquakes) shallow (1–5 km) and increased from 1 event/year in the early 1980s (extraction 1 km³/year), up to 13 events/year in the 1990s (average annual extraction > 6.4 km³). Results indicate that faults played a role in localizing deformation given that deformational sites and InSAR-based high subsidence rates (? 4 to ? 15 mm/year) were largely found within, but not outside of, NW–SE-trending grabens bound by the Kahf fault system. Findings from the analysis of Gravity Recovery and Climate Experiment solutions indicate that sustainable extraction could be attained if groundwater extraction was reduced by 3.5–4 km³/year. This study provides replicable and cost-effective methodologies for optimum utilization of fossil aquifers and for minimizing deformation associated with their use.  相似文献   

Evaluation of phosphorus bioavailability in El Mex Bay and Lake Mariut sediments     

Naglaa F. Soliman  Gehan M. El Zokm  Mohamed A. Okbah 《国际泥沙研究》2017,32(3)

Phosphorus (P) fractions and their bioavailability in the sediments from El Mex Bay and Lake Mariut in Egypt were investigated using different chemical extraction methods. Sodium bicarbonate (NaHCO3) extractable P (Olsen-P) was the largest fraction (14.42%), followed by algal available P (AAP) (3.56%), water soluble P (WSP) (0.79%), and readily desorbable P (RDP) (0.06%) for El Mex Bay. While AAP con-tributed 9.94% to total P in sediments from Lake Mariut, Olsen-P 8.53%, WSP 4.11%, and RDP 0.92%. Summation of the bioavailable P fractions didn't exceed the sediment quality guidelines, and, therefore, P doesn't represent a danger to marine organisms. Correlation coefficients showed that no apparent relations between total P (TP) and iron (Fe), aluminum (Al), and calcium (Ca) in the sediments. Fur-thermore, Fe:P ratio was less than 15 indicting that there was not enough Fe in surface sediments to bind to P at most of the sampling sites. The positive correlation between TP and organic matter (OM) for Lake Mariut and El Mex Bay sediments indicated that the organic matter content of the sediment was a useful predictor of the total phosphorus content. Data from this study constitute a baseline of phosphorus bioavailability in sediments from El Mex Bay and Lake Mariut and could be used as a reference for future studies on the changes of bioavailable and residual phosphorus fractions over time.  相似文献   

Impacts of future land cover and climate change on the water balance in northern Iran     

Sharif Joorabian Shooshtari  Mehdi Gholamalifard  Mahmood Azari  Roberto Serrano-Notivoli  Juan Ignacio López-Moreno 《水文科学杂志》2017,62(16):2655-2673

We evaluated the potential impacts of future land cover change and climate variability on hydrological processes in the Neka River basin, northern Iran. This catchment is the main source of water for the intensively cultivated area of Neka County. Hydrological simulations were conducted using the Soil and Water Assessment Tool. An ensemble of 17 CMIP5 climate models was applied to assess changes in temperature and precipitation under the moderate and high emissions scenarios. To generate the business-as-usual scenario map for year 2050 we used the Land Change Modeler. With a combined change in land cover and climate, discharge is expected to decline in all seasons except the end of autumn and winter, based on the inter-model average and various climate models, which illustrated a high degree of uncertainty in discharge projections. Land cover change had a minor influence on discharge relative to that resulting from climate change.  相似文献   

Characterization of a carbonate reservoir using elastic full-waveform inversion of vertical seismic profile data     

Eric M. Takam Takougang  Mohammed Y. Ali  Youcef Bouzidi  Fateh Bouchaala  Akmal A. Sultan  Aala I. Mohamed 《Geophysical Prospecting》2020,68(6):1944-1957

Two-dimensional elastic full waveform inversion was applied to two lines extracted from a spiral three-dimensional vertical seismic profile data acquired in an oilfield offshore, Abu Dhabi, in the United Arab Emirates. The lines were selected to be parallel and perpendicular to the plane defined by the deviated borehole. The purpose of the inversion was to derive high-resolution elastic properties of the subsurface. After pre-processing, the data were band-pass filtered with a minimum frequency of 3.5 Hz and a maximum frequency of 30 Hz. A sequential inversion approach was used to mitigate non-linearity. The pre-processing of the data consisted in the removal of bad traces, followed by amplitude and phase corrections. High-resolution P- and S-wave velocity models that show good correlations with the available sonic logs were obtained. The results of the inversion suggest that the oilfield consists of a stack of layers with varying lithology, porosity and possibly fluid content.  相似文献   

Observed spectrum in the South China Sea during storms     

Latheef  Mohamed  Abdullah  Mohd Nasir  Jupri  Mohd Faieez Mohd 《Ocean Dynamics》2020,70(3):353-364

Ocean Dynamics - The present work focuses on the measured wave spectrum in the South China Sea (scs) during storms. The measured spectra have been obtained from surface elevation measurements...  相似文献   

Newspapers as a validation proxy for GIS modeling in Fujairah,United Arab Emirates: identifying flood-prone areas     

Yagoub  M. M.  Alsereidi  Aishah A.  Mohamed  Elfadil A.  Periyasamy  Punitha  Alameri  Reem  Aldarmaki  Salama  Alhashmi  Yaqein 《Natural Hazards》2020,100(1):111-132

Prediction and control of blast-induced ground vibration is a matter of concern in mining industry since long. Several approaches ranging from scaled distance regression, different numerical methods to wave superimposition theories have been tried by many researchers for better prediction and control of blast-induced ground vibration. Signature hole analysis is one of the popular simulation methods to predict the ground vibration generated due to production blast. It superimposes the recorded signature hole waveform using a computer program to predict the production blast-induced vibration. The technique inputs the designated time of detonation of each hole and superimposes the waves generated by each hole to predict the nearest value of peak particle velocity and frequency of blast-induced ground vibration. Although a very useful approach, it requires a computer program to simulate the linear superimposition of waveforms. The simulation is not possible for every blast as it takes time and also is difficult for field engineers to simulate every time, whereas it is always easy for blasting engineers to adapt and use an empirical equation/approach for prediction and control of blast-induced ground vibration than simulation. In this paper, an attempt has been made to develop an innovative and simplified analytical approach of signature hole analysis. The simplified sinusoidal wave equation is obtained from recorded signature hole ground vibration waveform properties and is superimposed mathematically according to the multi-hole blast design to predict the production blast-induced ground vibrations. The validation of the developed approach was done in three different sites, and up to 15% more accuracy in prediction of the blast, vibrations are achieved in comparison with signature hole analysis prediction.

  相似文献   

An LMI approach to H∞-control of time-delay systems for the benchmark problem     

Magdi S. Mahmoud  Mohamad J. Terro  Mohamed Abdel-Rohman 《地震工程与结构动力学》1998,27(9):957-976

In this paper, three H_∞-control design methods are developed and applied to a three-storey building with an active mass damper as a control mechanism. The system of equations of the structural system, including the actuator and sensors, has been developed directly from experimentally derived data which forms the basis of the benchmark study discussed in this paper. The building plus the damper are modelled as a nominally linear system with input as well as state delays. Feedback control synthesis are first performed by using either of the two forms; the first is a pure state feedback and the other is a static output feedback. The analytical results are cast into a Linear Matrix Inequality (LMI) framework which can be solved numerically by efficient interior-point methods. The developed system is subjected to two historical earthquake excitation inputs (ElCentro and Hachinohe) and to the Kanai–Tajimi filter. The response is given in the form of indices in order to compare with other solutions of the benchmark problem. In addition, simulation results pertinent to the developed techniques are presented. © 1998 John Wiley & Sons, Ltd.  相似文献   

Discussion of “Experimental study on the hydraulic conductivity of calcareous sand in South China Sea”     

Mohamed Khaled Salahou  Weihua Guo 《Marine Georesources & Geotechnology》2018,36(3):297-298

Hydraulic conductivity of the granular soils depends on many factors including the soil density and the particle size distribution. For internally unstable soils, the hydraulic conductivity could be changed beyond a critical value of hydraulic gradient. This discussion calls attention to the effect of the internal stability on the hydraulic conductivity, where the internal stability of the soils is assessed and the critical hydraulic gradient is computed using some theoretical methods, and such calculations could be used to plan the experimental tests.  相似文献   

Discussion of (anisotropic hydraulic conductivity and critical hydraulic gradient of a crushed sandstone–mudstone particle mixture)     

Mohamed Khaled Salahou  Yousif A. H. Dallo 《Marine Georesources & Geotechnology》2018,36(2):199-201

A discussion is presented here to the work of Wang and Qiu including some notes about the analysis and the correlations of the results. First, we show that there is no clear relationship between the critical hydraulic gradient and the uniformity coefficient. Also we show that the internal erosion mechanism of soils with bimodal structure is different from that for soils with no bimodal structure. Finally, we emphasis that the anisotropy in the hydraulic conductivity is not related to the uneven compaction only but also to the particle arrangements and connectivity between pores.  相似文献   

Automated morphological classification of galaxies based on projection gradient nonnegative matrix factorization algorithm     

I. M. Selim  Mohamed Abd El Aziz 《Experimental Astronomy》2017,43(2):131-144

The development of automated morphological classification schemes can successfully distinguish between morphological types of galaxies and can be used for studies of the formation and subsequent evolution of galaxies in our universe. In this paper, we present a new automated machine supervised learning astronomical classification scheme based on the Nonnegative Matrix Factorization algorithm. This scheme is making distinctions between all types roughly corresponding to Hubble types such as elliptical, lenticulars, spiral, and irregular galaxies. The proposed algorithm is performed on two examples with different number of image (small dataset contains 110 image and large dataset contains 700 images). The experimental results show that galaxy images from EFIGI catalog can be classified automatically with an accuracy of ～93% for small and ～92% for large number. These results are in good agreement when compared with the visual classifications.  相似文献