Hydrochemical and GIS-based evaluation of groundwater suitability for irrigation using IWQI in the desert hinterland of western Nile Delta Egypt

Abstract

Groundwater is an essential resource for irrigation in the newly reclaimed regions of the New Delta in Egypt, where the sustainable advancement of agriculture heavily depends on its quality. This study aimed to assess the suitability of the water for both drinking and irrigation purposes in the western hinterland of the Nile Delta, and to aid water resource managers and policymakers in recognizing the potential risks linked to the utilization of this water. A total of 41 groundwater samples were analyzed for major cations and anions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃⁻, Cl⁻, SO₄²⁻), and key irrigation indices, such as SAR, Na%, RSC, PI, KR, MAR, and IWQI were calculated. The primary findings revealed that the Irrigation Water Quality Index (IWQI) classified 7.32% of the samples as having moderate restrictions, 34.15% as having high restrictions, and 58.54% as having severe restrictions, underscoring the widespread issues of salinity and sodium hazards across different zones. The results indicated that most samples fall within acceptable to permissible limits; however, high levels of Na⁺ and Cl⁻ in certain areas suggest potential challenges related to sodicity and salinity. Spatial distribution maps confirmed that these risks are localized and closely linked to soil texture and irrigation practices. Principal Component Analysis (PCA) illustrated that the first two components account for nearly 70% of the total variance, with salinity-related variables (EC, TDS, Na⁺, Cl⁻, SAR) being the dominant factors, followed by sodium–chloride enrichment, carbonate equilibria (HCO₃⁻, RSC, pH), and evaporation effects. In conclusion, the findings highlight that while a considerable portion of the groundwater is still suitable for irrigation, ongoing use without proper management could result in decreased permeability and heightened soil sodicity. Therefore, it is advisable to adopt adaptive management strategies, including crop selection, blending of water sources, and regular monitoring.