Abstract
Ethiopia considered to have abundant water resources potential is facing
flood and drought possibly from poor water resource management and
reluctant policy. Awash river basin classified in to upper, middle, and
lower crosses Ethiopian plateau through the Afar desert. Among the basin
classes, the upper basin is socio-economically important wherein the
early and modern agriculture start is the most irrigated basin. Addis
Ababa the capital and different major towns are getting their domestic
Water supply from this basin. The study aimed to assess the basin’s
hydroclimate variability under the climate change during study time
series. Basin’s Metrological trend is analyzed with systematic
topographical classes as Lowland, midland, and highland. Lowland (Mojo
and Bishoftu station) revealed nonsignificant increasing trend except
for the Bona and Birraa season respectively. Midland area stations
revealed a seasonal decrease with precipitation except Asgori station is
increasing in the Birraa season. Highland area stations exhibited a
decreasing trend annually and in Arfaasaa seasons except Sendafa station
got an increasing trend. Addis Alem station decreased Annually at a 95%
significance level while other are statistically insignificant. The
streamflow of the basin evaluated with Awash-Hombole and Mojo main
tributary river flow. Awash-Hombole main tributaries resulted in
increasing trend annually and during Ganna season. Berga, Holota,
Melka-Kunture and Hombole stations are insignificantly increasing
annually. Mojo main tributary resulted in a significant decreasing trend
during the Arfaasaa, Ganna and Birraa season at 99% significant level.
Basin streamflow change within the study time series is observed within
the model’s observation confidence interval of 95% except for the 1996
steam flow. Therefore, there is change observed within the basing both
with rainfall and streamflow according to basin’s topographic nature.
Thus, the basin’s hydroclimate variated by 11.38% and 38.19% rainfall
and streamflow respectively from the mean value within the study time
series.