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Mapping groundwater conditions in different geological environments in the northern area of UAE using 2D earth resistivity imaging survey 总被引：1，自引：1，他引：0
A. M. Ebraheem M. M. Al Mulla M. M. Sherif O. Awad S. F. Akram N. B. Al Suweidi A. Shetty 《Environmental Earth Sciences》2014,72(5):1599-1614
A water resources database was developed and used to characterize the geological and hydrogeological settings of groundwater aquifers in the northern part of the United Arab Emirates. An intensive 2D Earth Resistivity Imaging (ERI) survey was conducted in selected areas to assess the available groundwater resources and delineate the salt-water intrusion. Drilling information of the existing monitoring wells as well as their records of water table elevations and groundwater salinity were used to measure the horizontal and vertical variations in lithology, degree of saturation, and groundwater salinity and thus to improve the interpretation of ERI data. The results of the chemical analyses of water samples collected from the wells along with the 2D ERI survey profiles were used to obtain an empirical relationship between the inferred earth resistivity and the amount of total dissolved solids. This relationship was used along with the true resistivity sections resulting from the inversion of 2D ERI data to identify and map three zones of water-bearing formation (fresh, brackish, and salt-water zones) in the coastal areas. The results indicated that the depth to the fresh-brackish interface exceeded 50 m at the upstream of the wadies and was in the order of 10 m or less in the vicinity of shoreline. Because of the high resistivity contrast between dry and water saturated fractured rocks; this method was very successful in detecting water-filled fractures and cavities in the carbonate aquifer. The application of this method was unsuccessful in clayey aquifers as it was not possible to isolate lenses of gravel and/or saturated with saline or brackish water from the surrounding clayey materials. 相似文献
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M. M. Sherif A. M. Ebraheem M. M. Al Mulla A. V. Shetty 《Environmental Earth Sciences》2018,77(11):412
In this study, the first groundwater recharge map for United Arab Emirates (UAE) was developed using the recharge potential and water table fluctuation methods. Recharge potential estimates were made using information about infiltration rate, soil type, ground slope, geological and hydrogeological factors, and the availability of rainfall harvesting infrastructure and were validated by measurements of water table rise in alluvial aquifers in wadis. Based on this information, the total recharge in the UAE is estimated to be about 133 million cubic meters per year (MCM/year). Annual recharge rates are calculated to vary between 1 and 28% of precipitation in the different regions of UAE depending on several natural and manmade parameters including, among others, recharge enhancing infrastructure. Estimates from the two methods are 98% in agreement; which suggests that the recharge potential method is suitable for estimating aquifer’s recharge in UAE and arid regions. The water table fluctuation method was found to be more suitable for assessing recharge through gravel plains and wadis in mountainous areas. 相似文献
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This study was conducted to collect historical land use information that would help explain the historical patterns in accumulation
of sediment and phosphorus in Lake Pepin documented by Engstrom et al. (J Paleolimnol, this issue). A wide range of historical factors including cropping systems, phosphorus applications from fertilizer and manure, human
and animal populations, river flows and phosphorus discharges from waste water treatment plants were studied using statistical
methods. Results showed that sediment losses from the Minnesota River basin are significantly correlated with historical increases
in river flows, row crop production acreage and basin population. Total phosphorus accumulations in the sediments of Lake
Pepin are significantly correlated with increased phosphorus discharges from metropolitan area wastewater treatment plants,
and increases in row crop acreage and river flows. Total phosphorus inflows to Lake Pepin are significantly correlated with
increases in river flows, row crop acreage and phosphorus fertilizer applied to agricultural lands.
This is one of eight papers dedicated to the “Recent Environmental History of the Upper Mississippi River” published in this
special issue of the Journal of Paleolimnology. D. R. Engstrom served as guest editor of the special issue. 相似文献
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A. M. Ebraheem M. M. Sherif M. M. Al Mulla S. F. Akram A. V. Shetty 《Environmental Earth Sciences》2012,67(3):845-857
Drilling information, historical water table levels, groundwater salinity records of the existing water wells in Wadi Al Bih area, United Arab Emirates, were stored in a geodatabase and used to characterize the geological and hydrogeological settings of this area. A 2D earth resistivity imaging survey was conducted for the first time in the Northern UAE to determine the potential of the Quaternary aquifer and its groundwater quality in the areas where there are no monitoring wells. The results of the chemical analyses of the collected groundwater samples together with the inversion results of the resistivity data were used to draw a total salinity map and determine the spatial variations in groundwater quality. The inversion results of the 2D earth resistivity imaging data indicated that the Quaternary aquifer in the study area is in a good connection with the underlying carbonate aquifer. It also indicated that the carbonate aquifer is of major regional and vertical extension and it contains the fresh water in this area. The data stored in the developed database were used to produce different types of geopotential maps. 相似文献
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Soil and water conservation measures improve soil carbon sequestration and soil quality under cashews 总被引：2，自引：1，他引：1
Gopal Ramdas Mahajan Bappa Das Sandrasekaran Manivannan Begur Lakshminarasimha Manjunath Ram Ratan Verma Sujeet Desai Rahul Mukund Kulkarni Ashish Marotrao Latare Reshma Sale Dayesh Murgaonkar Kiran Puna Patel Shaiesh Morajkar Ashwini Desai Natasha Barnes Heena Mulla 《国际泥沙研究》2021,36(2):190-206
Land degradation is becoming a serious problem in the west coast region of India where one of the world's eight biodiversity hotspots,the‘Western Ghats’,is present.Poor land management practices and high rainfall have led to increasing problems associated with land degradation.A long-term(13-year)experiment was done to evaluate the impact of soil and water conservation measures on soil carbon sequestration and soil quality at three different depths under cashew nut cultivation on a 19%slope.Five soil and water conservation measures-continuous contour trenches,staggered contour trenches,halfmoon terraces,semi-elliptical trenches,and graded trenches all with vegetative barriers of Stylosanthes scabra and Vetiveria zizanoides and control were evaluated for their influence on soil properties,carbon sequestration,and soil quality under cashews.The soil and water conservation measures improved significantly the soil organic carbon,soil organic carbon stock,carbon sequestration rate and microbial activity compared to the control condition(without any measures).Among the measures tested,continuous contour trenches with vegetative barriers outperformed the others with respect to soil organic carbon stock,sequestration rate,and microbial activity.The lower metabolic quotient with the measures compared to the control indicated alleviation of environmental stress on microbes.Using principal component analysis and a correlation matrix,a minimum dataset was identified as the soil available nitrogen,bulk density,basal soil respiration,soil pH,acid phosphatase activity,and soil available boron and these were the most important soil properties controlling the soil quality.Four soil quality indices using two summation methods(additive and weighted)and two scoring methods(linear and non-linear)were developed using the minimum dataset.A linear weighted soil quality index was able to statistically differentiate the effect of soil and water conservation measures from that of the control.The highest value of the soil quality index of 0.98 was achieved with continuous contour trenches with a vegetative barrier.The results of the study indicate that soil and water conservation measures for cashews are a potential strategy to improve the soil carbon sequestration and soil quality along with improving crop productivity and reducing the erosion losses. 相似文献
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David J. Mulla 《地球表面变化过程与地形》1988,13(5):389-405
Topography for four areas in the Palouse region of southeastern Washington State having different patterns and encompassing areas of about 900 ha each were quantitatively compared and described using two-dimensional semi-variograms and periodograms. The four areas studied were from the Garfield, La Crosse, Thornton, and Wilcox quadrangle topographic maps. Semivariance of elevation residuals were modelled using a combination of spherical, periodic, or linear semivariogram models. The range of the spherical component was interpreted as a relatively short-range scale of correlation which was not periodic. For each of the study areas a model was developed to describe the variation in range with orientation. Values for the range from this model reached maximum values of from about 700 m to 800 m at an orientation of from 35° to 55° (approximately northeast) in each study area. This orientation was interpreted as the dominant direction of non-periodic small-scale landscape features. The wavelength and amplitude of the periodic semivariogram component, which were highly correlated, were interpreted in terms of parallel northeast-trending ridges having relatively long scales of periodic correlation varying in size from about 1350 m to 2100 m. This attempt to identify the dominant orientation of periodic landscape features using models for the wavelength and amplitude was, however, not completely definitive. Two-dimensional spectral analysis provided significantly more detail concerning orientation and wavelengths of the periodic topographic patterns than the semivariogram analysis. In the Garfield study area, spectral analysis identified north-trending ridge systems separated by a wavelength of 1494 m and northeast-trending systems with a wavelength of 747 m. In the La Crosse study area, both north and northeast-trending patterns were identified having periodic spacings of 980 and 735 m. North-trending ridges separated by wavelengths of 996 m and northeast-trending ridges separated by wavelengths of 747 or 996 m were the predominant periodic features of topography in the Thornton study area. In the Wilcox study area, northeast-trending ridge systems separated by wavelengths of 373, 498, or 996 m were detected. A comparison of the results from geostatistical and spectral analysis of these complex topographic surfaces shows that each approach had significant strengths and weaknesses. Two-dimensional analysis with semivariograms was the only method which could be used for identifying the correlation scale and orientation of relatively small non-periodic landscape features. Two-dimensional spectral analysis accurately identified the predominant orientation of relatively large periodic features in topography, whereas semivariogram analysis was somewhat inconclusive. Also, semivariograms were generally unable to detect the presence of multiple or harmonic periodicities operating at different wavelengths along a given orientation. 相似文献
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