Hydrogeochemical processes regulating groundwater quality and its suitability for drinking purposes in the recent alluvial plain, Blue Nile Region, Sudan.

Abstract

Groundwater is becoming a critical freshwater source in the Blue Nile Region, Sudan. However, overexploitation and contamination increasingly threaten its sustainability. This study evaluates the hydrogeochemical processes influencing groundwater and its suitability for drinking purposes in the recent alluvial plain. A total of 342 groundwater samples were collected from domestic wells and monitoring boreholes in 2022 for hydrochemical and multivariate statistical analysis. The results revealed that the groundwater is predominantly of HCO₃-Ca·Mg and HCO₃-Ca·Na facies, reflecting the influences of natural processes like mineral dissolution and ion exchange. The key factors affecting groundwater quality include rock-water interactions and anthropogenic influences. Most groundwater samples complied with the World Health Organization (WHO, WHO. (2022). Fourth edition incorporating the first and second addenda Guidelines for drinking-water quality) and Sudanese drinking water standards. However, F^- concentrations exceeding permissible levels were detected in northeastern and southwestern boreholes, posing potential health risks. Elevated total dissolved solids (TDS) were linked to mineral dissolution and agricultural runoff. The Water Quality Index (WQI) categorized 39.42% of samples as excellent, 50.72% as good, and 9.57% as poor to very poor, with 0.29% unsuitable for drinking. Areas with low human activities exhibited better water quality, while compromised samples correlated with nitrate contamination, salinity, and poor waste management practices. This study provides a robust foundation for developing sustainable groundwater management strategies to mitigate contamination risks and secure safe drinking water access.