Abstract:
The main aim of this thesis is to study the existing and future water availability under
climate change in upper awash sub-basin which contributes significant flow to Koka dam
and also on water allocation of the existing and planned water resource projects
(irrigation, hydropower, industries, livestock etc.) in the upper awash.
HEC-HMS hydrologic model is used to assess the water availability of sub-basin. The
future stream flow forecasted in the sub-basin were simulated by the dynamically
downscaled A1B scenarios known as RCP 4.5 (Representative Concentration Pathways)
has been adopted from CORDEX archive and bias correction were done by using power
transformation equation before using in HEC-HMS model. The result of future water
availability from 2006 to 2031 in sub-basin was found to be nearly 1001 MMC.
The Water Evaluation and Planning System (WEAP) model is used for optimal water
allocation for existing and proposed water resource projects using the monthly based data
in both the demand side and supply sides and by priority setting situation for demand
sites. The reference period used for the simulation ranges from 1981-2009 while the
future scenario period ranges from 2006-2031.
The monthly water requirement for each crop mainly sugarcane is estimated using
Cropwat 8.0 software by adopting Penman-Monteith approach and crop coefficient of the
crop. The existing irrigation projects were around 95,155 ha while in the future scenario
period the irrigable land expected to increase by 21,103 ha. According to reference
scenario the downstream irrigation project shows the highest supplied volume about
479.4 MCM annually. According to future scenario period the UV1 and UV3 irrigation
projects shows increasing water demand from the refinance period by about 203.5 and
357.5 MCM annually due to expansion of the irrigation projects. The annual water
demand and supplied for the reference period found to be 1716.3 MCM while the demand
increases to 1953.3 MCM for the future scenario with no unmet demand.
