Ground Water Quality Evaluation using WQI and GIS Technique in the Al-Samawa City -Iraq

Ground water quality evaluation is the first step toward a good management of water resources to limit impacts on irrigation and drinking water. The objective of this study is to propose a technique to assess the groundwater quality and to generate a spatial variation map in terms of suitability for irrigation and drinking water in Al-Samawa city-Iraq. Groundwater samples were collected from 45 wells at different locations during (2013). The physical and chemical parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), K+, Na+, Mg2+, Ca2+, Cl1- , SO42-, HCO3- , NO3- have been analyzed to determine geological and non-geological source of contamination. The results were evaluated in detail and compared with WHO guidelines for irrigation water (2004) and drinking water standard by Iraqi and WHO (2011).Overall chemical analytical study using Sodium Adsorption Ratio (SAR) and Sodium percentage (Na%) values reveals that 93% of the ground water samples fall into the unsuitable for drinking and irrigation purposes when SAR is used and 86.6 % of samples fall into the permissible when Sodium percentage (Na%) is used. The most effective way to describe the quality of water is Water Quality Index (WQI). Correlation matrix for the studied parameters and (WQI) are significantly correlated among each other and for the most 11 parameters (high correlation coefficients). There is no relation between (WQI) and the parameters (pH, K and NO3) .The results demonstrate that seven water tests fall into the poor WQI. A large portion of the specimens (28) fall into the extremely poor water WQI class. Ten samples fall into the unsuitable WQI classification. TDS and SO4 were highly interrelated with WQI. The coefficients of determination were 0.90 and 0.94 respectively. The parameters NO3 and PH have a minimum negative correlation with WQI. Multiple linear regression equation correlating the highly interrelated parameters (TDS and SO4) and WQI are simulated with (R2 =0.952).MLR equation is very important in prediction the future WQI with knowing of some parameters like the TDS which is an important physicochemical parameter of drinking water quality. The present investigation exhibits high effectiveness for GIS to analyze complex spatial information and groundwater quality mapping. It shows higher concentration of groundwater salts in northeastern part of the study area. The overall ground water quality is not suitable for drinking water and irrigation water. It may be used for drinking after treatment process. It is currently so easier for a decision