Study of the quality index of groundwater (GWQI) and its use for irrigation purposes using the techniques of the geographic information system (GIS) of the plain Nekor-Ghiss (Morocco)

Abstract

Groundwater is an indispensable source of water for drinking water supply, agriculture and industry worldwide. In arid and semi-arid regions, groundwater has seriously deteriorated in recent decades due to environmental changes, anthropogenic activities and marine intrusion. A total of 79 groundwater samples from the Nekor-Ghiss plain were sampled for major chemical ion analysis. These analyzes showed that the water samples were highly mineralized (>1,500 mg/L), with hardness (83.5% of the samples were very hard) and high concentrations of chemical elements, such as Cl−, Mg2+, Na+ and SO42-. To assess the quality of water in the study area for irrigation and consumption purposes, we used the quality index (GWQI) as well as a multi-criteria analysis based on “geographic information system” by assigning a weight to the different water quality parameters. Also, Piper and Durov diagram was investigated. The results of the study were focused on the water quality parameters of the collected groundwater samples, such as the sodium adsorption rate (SAR), the percentage of soluble sodium (Na%), the Residual Sodium Carbonate (RSC) and Permeability Index (PI) Majority of water samples in the study area are suitable to be used for irrigation. Magnesium Risk (MH) and Kelley’s Ratio Kelly ratio. 51.9% unsuitable samples to 59.49% good samples for irrigation purposes. Monitoring the quality and quantity of groundwater is crucial for the effective and sustainable management of this valuable resource. According to the results obtained, it appears that 92% of all the samples are located in the domain of frequent recharge waters of limestone and dolomitic aquifers, namely, Ca-Mg-HCO3. About 8% of the samples measured have a composition of the Ca-Na-Mg-HCO3 type.