The chemical composition of groundwater is affected by many features, including the impact caused by surrounding rocks. The Nile aquifer is surrounded by the calcareous structural plateau along the Assiut governorate on both sides. This paper aims at studying the effect of surrounding rocks on the chemical composition of groundwater in the Nile aquifer along the Assiut governorate. Fifty-five samples were taken from drinking water stations and irrigation wells in 2015, and then analyzed chemically in water and soil fertility laboratory located in the irrigation ministry in Assiut. Aquachem software package was used to determine the groundwater type and rock source deduction. Piper-trilinear diagram was plotted to show the hydrochemical facies. Furthermore, Gibbs diagram was applied to determine the correlation between water composition and aquifer lithological characteristics. The results revealed that nearly all of the groundwater samples drop in the water-rock interaction field. The results of rock source deduction show that the ratio of Cl to the sum of anions is less than 0.8 for all samples, concluding that the rock weathering is dominant. According to the criterion of TDS values, 78% of all the samples indicated that the carbonate weathering is prevalent; in turn, the ratio of Mg to Ca plus Mg shows that limestone-dolomite weathering is predominant. These results confirm that the calcareous structural plateau surrounding the Nile aquifer along the Assiut governorate has an effect on the groundwater chemistry by interacting between groundwater and limestone rocks which are the main component of the calcareous plateau.
Understanding the rheology behavior of non-Newtonian mine paste backfill is critical to ensure its flowability in the pipeline distribution system. Several rheology measurements methods for paste backfill have been proposed in the literature to quantify the rheology properties. However, there is no definite conclusion on the best measurement method to correctly predict pressure loss in the paste backfill pipeline system with a high solid concentration. This study addresses the issue by comparing several rheology measurements techniques, i.e., coaxial rheometer with various configurations, vane viscometer, and slump and pipe loop tests, with regard to Bingham yield stress, Bingham plastic viscosity, and pressure loss using statistical analysis. The paste backfill samples are prepared from two different mine tailings: finer and coarser particles. The pressure loss from the pipe loop test along with Buckingham-Reiner transformation using the Darcy-Weisbach equation are used as reference properties. The results suggest that a simple slump test can accurately predict the Bingham yield stress for coarser tailing. At the same time, a coaxial rheometer with MVDIN cup is found to predict the Bingham paste properties accurately for finer tailing.
The effect of high temperatures on rock’s thermophysical and mechanical properties is critical to the design of underground geotechnical applications. The current work investigates the impact of temperature on rhyolitic turf rock’s physical and mechanical properties. Intact cylindrical core rock samples were heated to different temperatures (200, 400, 600, and 800 °C). The uniaxial compressive strength (UCS) and elastic modulus of unheated and heated samples were determined as important mechanical properties. In addition, the effect of temperature on the physical properties of rhyolite rock (density, color, and absorption) was investigated in conjunction with its microstructural properties. The hardening of the rhyolitic rock samples was observed below 600 °C, at which point the UCS and elastic modulus decreased to 78.0% and 75.9%, respectively, at 800 °C. The results also show that heating does not significantly affect the density and volume of permeable pore space, but a color change can be observed at 400 °C and above. A microscopic analysis shows the change in microstructural properties of rhyolite rock after heating to 600 °C. Furthermore, the SEM observations of heated materials show structural particle displacements and microcracking, leading to apparent surface cracks.
Two DRASTIC models have been used in this study, which are generic and pesticide to get the groundwater vulnerable levels to pollution in the Nile aquifer along Assiut governorate. Groundwater vulnerability maps were produced using Geographic Information Systems (GIS). It has been found in map of generic DRASTIC model that the most of the study area is covered by moderate vulnerable and high vulnerable; where 55.2 % of the area is moderately vulnerable and 35.4 % has high level of vulnerability. However in the vulnerability map generated by pesticide DRASTIC model, the results concluded that about 64% of the study area has an extreme to high vulnerability to contamination, 34.6% has a moderate vulnerability and small areas occupy about 1.4% and has a low vulnerability.
This paper aims to turn complex groundwater data into comprehensible information by indexing the different factors numerically comparative to the standards of World Health Organization (WHO) to produce Water Quality Index (WQI). Water Quality Index (WQI) has been used to assess groundwater quality and Geographic Information Systems (GIS) has been used to create maps representing the spatial distribution of groundwater categories in Assiut governorate, Egypt. Water Quality Index has been computed by Un-weighted Arithmetic Water Quality Index (WQIUA) method and applied on 796 wells over eight years from 2006 to 2013. The results showed that WQIUA values for drinking purposes were high and most of them reached higher or close to 100, which indicated that the groundwater was polluted and unsafe for drinking. On the other hand, the quality index of groundwater for irrigation purposes in most of the study area ranges between 55.78 and 78.38 (poor and very poor category); this means that groundwater is moderately polluted and rather suitable for irrigation.
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