Assessment of Irrigation Water Quality and Suitability for Irrigation in the Fincha’a Valley Sugar Estate, Nile Basin of Western Ethiopia
A number of factors like geology, soil, effluents, sewage disposal and other environmental conditions in which the water stays or moves and interacts are among the factors that affect the quality of irrigation water. This study was conducted to determine the quality and suitability of different water sources for irrigation purpose in Fincha’a Valley Sugar Estate (FVSE), within the Nile Basin of Western Ethiopia. A total of 80 water samples were collected from different sources viz., reservoir, rivers, diversion weir, canals, pump stations, drains, and groundwater of the study area. Physico-chemical properties including electrical conductivity (EC), hydrogen ion concentration (pH), total dissolved solids (TDS), major cations (Ca, Mg, K, Na) and anions (HCO3 and Cl) were analyzed in the laboratory and sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and permeability Index (PI) were calculated from the major cations and anions studied for the criteria of irrigation water quality and suitability for irrigation. The study revealed that the values of EC, pH and TDS, and the amount of Cl-, HCO3, Na+, K+ , Ca2+ and Mg2+ varied from 100 to 730 µS cm-1, 6.6 to 7.3, 64 to 467.20 mg l-1,and 2.8 to 6.8, 2.04 to 5.6,3.8 to 7.8, 0.05 to 0.26, 8.4 to 19.9, 1.4 to 3.7 mmol l-1 and SAR, RSC, the PI values varied from 0.4 to 3. 9, -13 to -6.4 and 26.34 to 49. 9 %, respectively. The cationic and anionic constituents and SAR values of the samples increased from the upstream to the downstream. This is clear indication of the impacts of agricultural activities of the upstream and long-term irrigation in the downstream on the quality and suitability of water for irrigation purpose. If this trend continues, the gate for secondary salinization becomes significant. This necessitates the undertaking of certain management measures in the area for sustainability and productivity of the irrigation system in the FVSE.