Irrigated agriculture is a major human activity, which often leads to secondary salinization of land and water resources in arid and semi-arid conditions. Soil salinity is an enormous problem for agriculture under irrigation as it affects the growth and development of plants in Ethiopia; the problem is widespread in the rift valley areas where middle Awash and Amibara irrigated farms are present. Therefore, this study was conducted to investigate spatial variability and seasonal fluctuation of ground and surface water quality. Based on the existing piezometers points, additional ground water monitoring holes were repaired and installed at the previous points. Totally, about thirty monitoring piezometers were used in this study, which are found in both Fluvisols and Vertisols areas. A total of 155 water samples were collected at the months of August, September, October, November and December from ground water monitoring piezometers and Awash River, to evaluate the spatial variability and seasonal fluctuation of groundwater and Awash River water quality. Then, for all water samples, all salinity and sodicity parameters were determined in the laboratory. Based on the laboratory analysis results, the Awash River water quality is in the medium range for irrigation with regarding mean values of 1 ds/m ECw and 6.65 SAR. For the water of groundwater samples, collected from fluvisols area, the pH, ECw and SAR values ranged from 7.3 to 9.1, 1.31 to 13.1 and 2.86 to 66.98 with mean values of 8, 5.4 and 17.6, respectively, while the pH, ECw and SAR values ranged from 7.5 to 8.3, 0.9 to 7.68 and 3.87 to 11.37 with a mean values of 7.9, 3 and 6.2, respectively for groundwater samples collected from vertisol areas.

Keywords: ground water salinity and sodicity, Fluvisols and Vertisols