الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
For several reasons, groundwater is a major water supply in Egypt. For the assessment of groundwater content and aquifer insecurity in Faiyum depression, Western desert, Egypt, physiochemical parameters and DRASTIC model were used. Twenty four surface samples representing the main irrigation water and Thirty eight ground water samples representing the Quaternary aquifer. The pH, TDS, EC, Al, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Sb and Se physiochemical parameters of the samples collected were determined using normal analytical methods. For analyzing the obtained data, analysis and GIS techniques were used. The findings of the vulnerability index (VI), determined by the DRASTIC model showed that the vulnerability of the groundwater aquifer increases radially from the depression core to the peripheries of the study region. The integration of the water contamination indexes and the DRASTIC model is a valuable and applicable method for determining the consistency of groundwater using groundwater and aquifer physiochemical parameters.
Groundwater in Faiyum governorate has a particular importance where it is the source for fresh water used for drinking, agricultural, domestic, and industrial purposes. Thirty eight groundwater wells were available during summer 2017 and were analysis for physiochemical characteristics. These data has been used to evaluate groundwater for drinking and irrigation purposes by comparing physiochemical parameters with world health organization (WHO) standards. Results show that 60.5% of Na+ concentrations in groundwater samples are above this limit. 86.84% of K+ concentrations in groundwater samples are above this limit. The desirable limit for Ca2+ for drinking water is specified as 75 mg/l WHO (2011). About 84.2% of groundwater samples in study area exceed the permissible limit according to WHO standards. Most of the Mg2+ concentrations 84.2% are above the desirable limit of 50 mg/l. About 97.36% of total wells over the permissible limit of HCO3- which is120 mg/l. About 14 wells 36.84% are within the desirable limit of 250 mg/l. The desirable limit of Cl- for drinking water is specified as 250 mg/l according to WHO and 30 wells 78.94% are above this limit. Groundwater wells were classified according TDS as about 89.47 % of tested samples have contents ranging from >1000 mg/l.
These data has been used to preliminary evaluation of suitability of groundwater for irrigation purposes using groundwater quality indices which are TDS, RSC, TH, PI, MH, CAI and CR (Appendix XI). The TDS in groundwater varied between 614.3 and 8950 with an average value of 4782.15. The RSC in groundwater varied between -37.74 mg/l and -1.41 mg/l with an average value of -19.57 mg/l. The TH values of the study area varied between 256.4 and 2658.8 with an average value of 1457.6. The PI of the groundwater samples varied between 42.46 and 92.83 mg/l with an average value of 67.645 mg/l. The MH values of the study area varied between 28.42 and 73.42 mg/l with an average value of 50.92 mg/l. The CAI values of the study area varied between -1.49 and 0.3 with an average value of -0.595. The C.R values of the study area varied between 3.08 and 335.08 with an average value of 169.08.
DRASTIC index results showed that the vulnerability index values in the study area ranged from 111 to 149. DRASTIC index results indicated that the vulnerability levels of the groundwater aquifer varied from low to high, where the low vulnerability levels are found in the central part of the study area, and the vulnerability increases radially towards the peripheries of the study area as indicated by the vulnerability map.
The main groundwater aquifer in El Faiyum region is a Quaternary aquifer. It shows increasing signs of groundwater quality deterioration. Therefore, a comprehensive assessment of groundwater quality has been performed for determining the geochemical processes affecting the groundwater quality evolution and assessing groundwater quality for drinking and irrigation uses.
Physicochemical parameters, geochemical model (DRASTIC), and water quality indices (WQIs) are applied to improve water quality assessment and controlling mechanisms with help of statistical analysis and GIS techniques. Thirty eight groundwater samples from the Quaternary aquifer at depths less than 60 m. Thirteen physicochemical parameters including temperature (°C), TDS, pH, EC, K+, Na+, Ca+2, Mg2+, HCO3−, Cl−, SO42−, CO32−, and NO3− were measured by standard analytical techniques. The analytical findings reveal that the groundwater facies are Na-Cl, mixed Ca-Mg-Cl, and Na-Ca-HCO3 water types. The drinking water quality index (DWQI) results revealed that 58% of the groundwater samples are very poor quality, while 42% of samples are unsuitable for drinking uses. The irrigation water quality index (IWQI) results revealed that all groundwater samples range from 26.1 to 36.1, indicating a medium class of quality for irrigation purposes. These results reflect the influences of the high mineralization processes, cumulative effect of cation exchange, leaching processes from aquifer materials, contamination by irrigation return flow, and seepage from drains on the groundwater quality. In conclusion, utilization of physicochemical parameters, geochemical model, and WQIs can be considered as a promising and applicable approach to determine the controlling geochemical mechanisms and for assessing of groundwater quality in El Faiyum depression, Egypt.