Seasonal groundwater quality analysis in a drought prone agricultural region using GIS and IWQI for nitrate contamination insights

Abstract

The Hennaya Plain’s groundwater resources, which are crucial for agricultural irrigation, face significant quality challenges driven by human-induced environmental transformations. This study comprehensively evaluated groundwater quality during both dry and wet seasons. The assessment used an integrated approach that synergistically combined the Irrigation Water Quality Index (IWQI) with high-resolution nitrate content analysis as complementary diagnostic tools. This combined methodology enabled a detailed evaluation of seasonal groundwater dynamics. Thirty-nine groundwater samples were collected from wells distributed across the plain. The research systematically evaluated physicochemical parameters and their seasonal variations. The investigation revealed contrasting seasonal patterns in groundwater quality parameters. NO3−–N contamination increased markedly from the dry to wet season, with the percentage of samples exceeding permissible levels rising from 12.82 to 69.23%. Conversely, chloride contamination decreased during the wet season, with exceedances dropping from 23.07 to 10.26% of samples. IWQI analysis indicated a marginal improvement in overall water quality during the wet season, which contrasted with a simultaneous escalation in nitrate pollution from moderate to severe levels. The integrated assessment categorized irrigation water quality as moderate to poor, highlighting the intricate interactions between agricultural practices, seasonal precipitation, and groundwater chemistry. These findings underscore the urgent need for comprehensive groundwater management strategies that address seasonal variability and anthropogenic influences on water resources.