Abstract

Soil salinity is a  threat  for agriculture under irrigation as it affects the growth and development of plants and the problem is widespread in middle Awash where Amibara irrigated farms are present. Therefore, Measurements of groundwater depth were taken from thirty piezometers in the months of August, September, October, November and December to investigate spatial variability and temporal fluctuation of groundwater depth in Amibara irrigation scheme. Based on the field measurement, relatively shallow water levels were recorded in Vertisols area as compared to that in Fluvisols area with a mean values of 1.47 m and 3.01 m, respectively. On the other hand groundwater depth was influenced by the type of field cover and irrigation practices taken place during the sampling periods. Relatively deep water table was recorded in fields covered by shrubs and tree plants as compared to cotton and sugarcane fields with mean groundwater depth values of 4.87, 2.48 and 1.78 m, respectively. Seasonal fluctuation of groundwater depth was influenced with the climatic condition and irrigation practices occurred at the study area. In general shallower water tables were recorded at most piezometers in both soil types in the study area, which is resulted from poor irrigation management and destruction of surface and subsurface drainage structures to drain and remove excess water. Therefore Regular monitoring and evaluation of groundwater depth is required to reduce the accumulation of salt and to protect the irrigated land from abandonment.

Key words: groundwater, depth, spatial, temporal, fluvisols and vertisols.