Assessment of groundwater quality through hydrochemical and spatial analysis for domestic and agricultural uses

Abstract

Abstract Groundwater plays a crucial role in Southeastern Morocco, where arid climate conditions, recurrent droughts, and increasing agricultural demands make it the primary source of water for domestic and irrigation purposes. In the absence of previous studies on the Bouanane watershed (18,393 km²), this work represents the first scientific exploration aimed at providing reliable data on groundwater quality and paving the way for future research. The study evaluates groundwater suitability for drinking and irrigation through the application of water quality indices, particularly the Drinking Water Quality Index (DWQI) and the Irrigation Water Quality Index (IWQI). Fieldwork was conducted in April 2024 at nine strategically selected sampling stations. Results reveal considerable variability in groundwater quality across the region, shaped by both natural processes and human activities. While some sites meet the requirements for domestic and agricultural use, others show elevated mineralization that poses limitations for irrigation. Traditional indicators such as total hardness (TH), residual sodium carbonate (RSC), electrical conductivity (EC), and magnesium hazard (MH) did not fully capture these spatial variations. In contrast, the DWQI, adapted to regional conditions, effectively highlighted disparities, with values ranging from 64.06 to 242.23 (average 135.2). Based on this index, groundwater quality was classified into three equal categories (good, average, and poor), each representing 33.3% of the sampled wells (three wells per category out of nine). In terms of water usability, approximately one-third of the samples are suitable for direct human consumption, while the remaining two-thirds require treatment due to moderate to poor quality, mainly linked to salinity and mineralization. Overall, groundwater quality in the Bouanane watershed shows significant spatial variability and is not uniformly safe for drinking.