Evaluation of Groundwater Quality for Irrigation Purposes and Impact of Irrigation on Water in Golina River Basin, Northern Ethiopia

Abstract

Groundwater is a natural freshwater resource and very important for multipurpose use in the Golina River basin. The determination of groundwater resource sustainability depends on the groundwater quality evaluation for specific uses. The objectives of this research work are: (1) to evaluate the groundwater quality and suitability for irrigation purposes and (2) to study the impact of irrigation activities on groundwater quality in the Golina River Basin. Alluvial deposits, basalts, granite, and rhyolite are the main stratigraphic units in the area. 34 groundwater and 3 river water samples were collected from the study area for water quality analysis purposes. Parameters of pH and EC were measured using WTW Multi 3430 and HCO3- was measured using Hach digital titrator in the field while parameters of Na+, K+, Ca2+, Mg2+, Cl-, SO42-, NO3-, PO4, and F-, were analyzed in the lab using Ion Chromatography (IC) in the Technical University of Darmstadt. Besides these, total dissolved solids (TDS), total hardness (TH), sodium absorption ratio (SAR), magnesium hazards (MH), Soluble Sodium Percentage (SSP)(Na%), Residual sodium carbonate (RSC), Permeability Index (PI) and Kelly´s index (KI) were calculated and interpreted. Based on the result of the analysis, the abundance of cations in groundwater in the study area is arranged as Ca > Na > Mg > K, and the anions are arranged as HCO3- > SO42- > Cl- > NO3- > PO43-. Similarly, the result also showed that the common water types in the area are Ca2+-Mg2+-HCO3- and Mg2+-Ca2+-HCO3-. TDS, TH, EC, SAR, MH, SSP, RSC, PI and KI have respective mean values of 530.45 mg/l, 279 mg/l CaCO3, 657 µS/cm, 1.24, 48%, 26%, 0.23 meq/l, 61% and 0.57. The suitability of the dominant water points in the Golina River Basin for irrigation is moderate in terms of TDS, hard to very hard water for irrigation in terms of hardness, medium salinity for irrigation in terms of salinity hazard and low sodium hazards, suitable for irrigation in terms of magnesium hazards, good and excellent water for irrigation in terms of soluble sodium percentage, safe for irrigation in terms of residual sodium carbonate, good for irrigation in terms of the permeable index, and suitable water for irrigation in terms of Kelly ratio. Few water samples in the Golina River Basin show slight contamination of nitrate from the irrigation activities which needs special attention.