Groundwater is the most important natural resource required for drinking and agricultural purposes, especially in arid and semi-arid areas. The main aim of this research is to evaluate the groundwater quality of krimat aquifer and to identify the places with the best quality for drinking based on Water Quality Index (WQI) by using Geographical Information System (GIS).
The results of physico-chemical were compared to the standard values as recommended by the World Health Organization for drinking. However, the analyzed parameters pH, NO3, Na and K are below the desirable limits of WHO and the parameters Ca, TDS, SO4, Cl, Mg and HCO3 are above the desirable limits of WHO.
The contouring methods by exploiting Arcview spatial distribution maps of almost parameters with an interpolation technique (ordinary Inverse Distance Weighted), was used to obtain the spatial distribution of groundwater quality in krimat aquifer (Essaouira Region). The spatial distribution of groundwater quality patterns in the study area shows that the TDS values decreases from north-west to south-east. The results obtained showed that the WQI values range from 45 to 327 over 62 of the water samples and therefore can be categorized into five groups: excellent water to water unsuitable for drinking. In global, 52% of groundwater sites sampled in the study area had poor water quality, while 24% were good water. Regrettably, 18% of the samples indicate very poor water quality, 5% represent water unsuitable for drinking and 1% is excellent water. The results indicate that the most water is not safe for drinking and needs further treatment.