The hydrochemical characteristics and suitability to irrigation of spring waters of Mekelle area, Tigray, Ethiopia

Mekelle is the capital city of Tigray, located in Northern Ethiopia. Water samples collected from 18 springs, spatially covering the study area, were analyzed for their physical properties, and major cation and anion concentrations. Geologically, the study area is characterized by limestone, shale, limestone-shale-marl intercalation, and a dolerite rock unit. The fractured dolerite and fractured limestone are the main water-bearing geological formations. The objective of this research was to determine the groundwater type, from springwater chemistry, and evaluate its quality status for irrigation purposes. The total dissolved solids (TDS), chloride (Cl), and pH range from 330 to 1346 mg/l, 5.76 to 250.6 mg/l, and 7.01 to 8.13 respectively. A piper diagram showed the presence of three groundwater types in this area: calcium magnesium chloride, mixed type, and calcium magnesium bicarbonate hydrochemical facies. The dominant of the three, with about 70 %, was the calcium magnesium bicarbonate type. The sodium adsorption ratio (SAR) and sodium percentage (Na %) were calculated to determine the suitability of the water for irrigation. The SAR and Na % values ranged from 1.71 to 5.36 and 10.69 to 20.54, respectively. As per the international water quality permissible limit for irrigation, both values fall under suitable status. Therefore, based on the outputs of this research, all of the spring waters found in this thematic area can be directly used for irrigation without any prior treatment.&nbsp
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)