Spatial and Temporal Variability of Rainfall at Seasonal and Annual Time Scales at Tekeze River Basin, Ethiopia

Abstract

Understanding  climate variability using surface observed climatic parameters like rainfall at watershed spatial scale is a great input in decision making for practitioners in agriculture planning, water resources projects, rainfall-runoff modeling activities ,environmental impact assessment and civil works. This study examines the spatio-temporal variability of seasonal and annual rainfall totals over Tekeze river basin in Ethiopia. The indices were used over the basin based on data available from 28 meteorological stations having variable record length spanning from 1992-2009 for most of the stations. The data were subjected to main quality tests of outliers and homogeneity tests. Temporal variability was analyzed by coefficient of variability and spatial distribution and variability was investigated using ordinary kirging interpolation technique. The result showed: The annual and kiremt (June to September) season rainfall distribution are highest at the southwest part of the river basin and decrease to other directions. South and northeast part of the basin receive highest amount of Belg (February to May) season rainfall. The temporal variability of Belg rainfall is much higher than the kiremt rainfall. The spatial variability of annual and kiremt rainfall is higher than the spatial variability of Belg rainfall.

Keywords:  Seasonal Rainfall, Annual Rainfall, Temporal variability, spatial variability