GIS-BASED EVALUATION OF WATER QUALITY INDEX FOR GROUNDWATER RESOURCES NEARBY WASTEWATER TREATMENT PLANTS, EGYPTHEBA FATHI1 AND MUSTAFA EL-RAWY
The current study was carried out in the area around the major two conventional wastewater treatment plants (El Gabal EL Asfar and El Berka) at Greater Cairo, Egypt. The study area is bounded between latitudes 31o18' to 31o25' and longitude 30o10' to 30o16'. The high adoption of people on groundwater for different uses such as irrigation, drinking, and domestic activities in the surrounding area raised the attentions and concerns about the environment in this area. So, the main objectives of this study are to assess the groundwater quality in this area and to locate the pollution points related to these wastewater treatment plants. Fifteen groundwater samples were collected from different wells in the study area. Some physicochemical parameters (pH, alkalinity, BOD5, COD, TSS, TDS, SO4+2, Cl-, NH4+, NO3-) in addition to faecal coliforms were measured using the standard methods and compared to both World Health Organization (WHO) permissible limits and the Egyptian standards. The results showed that BOD5, COD, TSS, and NH4+ exceeded the maximum permissible limits. Multivariate statistical analysis was applied first to calculate the water quality index (WQI) which showed the decrease of water quality during the last three decades, and second to examine the correlations among the physicochemical parameters. Finally, a two-factor model, including the concentrations of pH, BOD5, COD, faecal coliforms, TSS and TDS was suggested and explained over 74 % of the total groundwater quality variance. Groundwater quality information maps of the entire study area have been prepared using the GIS spatial interpolation technique for all the above-mentioned parameters. The results obtained in this study and the spatial database established in GIS can be helpful for monitoring and management of groundwater pollution in the study area.
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