Multi-objective assessment of groundwater quality in Madinah City, Saudi Arabia

Abstract

In this research, a comprehensive assessment of groundwater quality in the city of Madinah, Saudi Arabia was carried out. The main objective was to evaluate whether the groundwater in the city is contaminated by leakage from different sources which will, in turn, give insight into the sources contributing to the shallow groundwater table rise (SWTR) that is observed in many locations in the city. In addition, the assessed groundwater quality helps in determining the most appropriate reuse of the excess water. Out of the 23 wells that were drilled in the study area for the purposes of this study, 20 wells were sampled for water quality analyses. Results showed that the groundwater in the study area is not contaminated by waste water or organic and inorganic compounds or by pesticides and herbicides from excess irrigation of agricultural areas. This suggests that the recent accelerated urban development in the city did not negatively impact the quality of groundwater and did not significantly contribute to SWTR in the city. Lithological description based on soil samples collected from drilled wells revealed the presence of impervious aquitard that extends over the aquifer in the city. This impervious aquitard has most likely played a role in protecting groundwater quality in the study area. Piper and Schoeller diagrams showed that the water type in the study area is a sodium-chloride type with a significant presence of sulfate. Results of this research give useful information about groundwater quality in Madinah city and will help authorities in planning the most appropriate reuse of excess water that may be pumped out to control SWTR.