Assessing the Impact of Loading Lake Beseka Water Into the Awash River AlongWith Potential Traits of Salinity/Sodicity Problems of Large Scale IrrigationFarms in Middle and Lower Awash Basin

Abstract

This study attempted to assess the current status of Awash River water quality with respect to spatialand temporal water quality variability along with the potential environmental effect of mixing the twowater bodies. The objectives of this study were to determine the effect of blending of Lake Beseka into Awash River with emphasis on Spatial and Temporal Variation to indicate the possible alternativerecommendation options. Soil samples were collected during the month of October and November2011. A total of 249 representative auger samples were taken from Melka Sedi and Melka Wererfarms at a soil depth of 0-30 cm. Considering extreme heterogeneity of soils of Melka Sedi area withrespect to salinity and sodicity and occurrence of wide range of the problem; attempt was made tocollect soil sample systematically from every farm units of Melka Sedi area. While for Melka Wererarea, with lesser extent of salinity and sodicity problems, soil samples was collected randomly at 2 kminterval. Collected samples were delivered to the laboratory of Werer Research Centre, air-dried,ground to pass through 2 mm sieve and prepared for selected chemical analysis. Water sample werecollected from the Awash River which is used as irrigation sources. The Awash River was sampledmonthly at 10 sampling points for one year (June, 2014 - July, 2015) including Lake Beseka startingfrom upper to lower Awash along the main river course. Water samples were also collected frommain irrigation and drainage canals of Amibara irrigation command area for one year.Collected water samples were subjected to the analysis of pH, EC, dissolved cations (Ca, Mg, Na andK), alkalinity (HCO3- and CO32-), Cl-, SO42-, NO3- Fluoride and Iron contents in the laboratory.EC and pH of the water samples were measured using conductivity meter and a digital pH meter,respectively (Greenberg et al., 1992). HCO3- and CO32- ions were determined by titration withstandard hydrochloric acid; Cl- by silver nitrate titrimetion method, and SO42- turbidimetrically byspectrophotometer. NO3- concentration in the samples was analyzed as per the methods outlined byMelese and Gemechu (2010), and fluoride and iron was determined following a standard analyticalprocedure. Ca and Mg ions were measured