Evaluation of spatiotemporal variations in groundwater physicochemical parameters and hydrochemical evolution in the Gidabo Watershed, Ethiopia

ABSTRACT Evaluating groundwater quality reveals its condition, supports water resource management, and minimizes health risks; yet, such studies in the Gidabo watershed remain limited. This study analyzes 30 groundwater samples from 15 sampling stations collected in the wet (October 2024) and dry (January 2025) seasons to assess spatiotemporal variations in physicochemical parameters and hydrochemical evolution. The parameters analyzed include temperature (T), pH, total dissolved solids (TDS), electrical conductivity (EC), and all major ions measured: Na+, Ca2+, Mg2+, K+, Fe2+, HCO3−, SO42−, Cl−, NO3−, CO32−, F−, and total hardness (TH). Results showed that most parameters met the WHO drinking water standards. Ion concentrations were lower in the wet season, and TDS levels were lower in the northern and southeastern parts of the watershed. Groundwater in the study area was largely of the Ca–Na–HCO3 type but exhibited a gradual shift toward more chemically evolved mixed types, including Ca–Na–Mg–HCO3 and Na–Ca–Mg–Cl–HCO3, with its chemistry primarily governed by rock–water interactions. This study provides valuable information for environmentalists and decision-makers in developing strategies for sustainable groundwater management.