Spatial mapping of irrigation groundwater quality of the High Mekerra watershed (Northern Algeria)

The spatial assessment of water quality for irrigation is of great importance for agricultural issues. Assessing the suitability of groundwater for irrigation is carried out for the first time in the High Mekerra watershed. Groundwater samples were collected during the wet season (March 2013) and the dry season (July 2013) and analyzed for determining the physicochemical properties. The indices used in the quality assessment were the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), sodium percentage (%Na + ), permeability index (PI), magnesium hazard (MH), Kelly’s ratio (KR), and irrigation water quality index (IWQI), incorporating the spatial variation using the GIS-based multi-criteria system. Result showed that most of groundwater samples have low sodium hazard and high to very high salinity hazard and could be used for irrigation on almost all types of soil with little risk of exchangeable sodium. The GIS-based multi-criteria system highlighted the spatial variation of groundwater quality for irrigation in the study area. This spatial distribution indicated that groundwater is generally of moderate quality and that the Ras el Ma aquifer quality is better than for Mouley Slissen aquifer.