Abstract:
Improper water allocation and ensuing conflicts are of serious concern for almost all countries
around the world. Climate change is anticipated to aggravate the already existing water stresses
initiating the enhancement of water use and allocation efficiency against various competing
demands. The aim of this study is evaluating the existing and future surface water resources
potential and demand in Gidabo catchment under changing climate and water resources
development scenarios. The demographic, irrigation and hydro-meteorological data in the
catchment was collected from different sources and future climate scenarios under RCP 4.5 and
RCP 8.5 have been used at their optimum level to find a better and more precise solution. The
power transformation and linear scaling have been used to remove the biases in precipitation and
temperature data. The baseline and future water resources potential of the catchment was
estimated using HEC-HMS model. The mean annual water availability and demand for baseline
period to be 619.87 MCM and 78.18 MCM respectively. The trends of projected climate
variables have shown positive change for both temperature and precipitation under both RCP 4.5
and RCP 8.5 emission scenarios. The mean annual future surface water resources potential of the
catchment was estimated as 682.77 MCM and 621.11 MCM under RCP 4.5 and RCP 8.5
respectively. The WEAP model considering three future demand scenarios namely; population
growth and increase in domestic water consumption, exploitation of pre-identified irrigation and
irrigation expansion was developed based on different sets of assumptions. The mean annual
future water demand in the near future year of 2021-2040 had shown an absolute increase
ranging from 100 MCM to 208 MCM; irrigation expansions being the highest water demanding
scenario. The study depicted that all the demands are fully met in baseline and future period
except for irrigation and industrial demand in future period during dry months throughout
January to March. Such a scarcity can be merely met storing excess water available during the
rainy season for further use during dry months
