Characterization and Classification of Irrigation Water Quality of Woito Irrigation Scheme in Benastemay District, Southern Ethiopia

Abstract

Every year a significant portion of semi-arid agricultural lands of Ethiopia becomes unproductive due to salinity and sodicity. For responsible land use and irrigation water management, it is essential to understand the salinity and sodicity status of irrigation water. As a result, this study was conducted to identify and classify the quality of woito irrigation scheme in Benatsemay District, Ethiopia. For the analysis of the irrigation water quality of the woito irrigation scheme, four representative samples were collected from the study area during both the wet and dry seasons. Irrigation water samples were taken and subjected to several analyses, including those for pH, TDS, EC, SAR, RSC, dissolved cations (Ca2+, Mg2+, Na+, and K+), and anions (SO42-, HCO3-, and CO32-), in order to determine the quality of the irrigation water used in the area under investigation. The results of investigation indicated that the pH of water samples was appropriate for irrigation. The EC of irrigation water was classified as medium and high during the wet and dry seasons. It was determined that the average SAR value was adequate for irrigation because it had little sodicity both during the wet and dry seasons. Additionally, the irrigation water had a suitable RSC value. Water quality analysis results for water samples taken from the research area generally showed salt issues to be a major concern. Salinity management and control strategies will therefore be employed to lessen the research area's exposure to long-term salinity threats. These actions include proper drainage, mixing irrigation water of different quality levels, adding mineral additions, replacing open irrigation canals with pipe systems, and using crops that can withstand salt. Therefore, additional research should be conducted to determine the status of groundwater quality in the studied area.