Assessment of Climate Change Impacts on the Hydrology of Upper Guder Catchment, Upper Blue Nile
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Date
2011-06
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Addis Ababa University
Abstract
Climate changes alter regional hydrologic conditions and results in a variety of impacts on water
resource systems. Such hydrologic changes will affect almost every aspect of human well-being.
The goal of this thesis is to assess the impact of climate change on the hydrology of Upper Guder
catchment located in Northwest of Ethiopia. The GCM derived scenarios (HadCM3 A2a & B2a
SRES emission scenarios) experiments were used for the climate projection. The statistical
Downscaling Model (SDSM) was used to generate future possible local meteorological variables
in the study area. The down-scaled data were then used as input to the Soil and Water Assessment
Tool (SWAT) model to simulate the corresponding future stream flow regime in Upper Guder
catchment of the Abbay River Basin. A semi distributed hydrological model, SWAT was
developed and Generalized Likelihood Uncertainty Estimation (GLUE) was utilized for
uncertainty analysis. GLUE is linked with SWAT in the Calibration and Uncertainty Program
known as SWAT-CUP.
Three benchmark periods simulated for this study were 2020s, 2050s and 2080s. The time series
generated by GCM of HadCM3 A2a and B2a and Statistical Downscaling Model (SDSM) indicate
a significant increasing trend in maximum and minimum temperature values and a slight
increasing trend in precipitation for both A2a and B2a emission scenarios in both Gedo and Tikur
Inch stations for all three bench mark periods. The hydrologic impact analysis made with the
downscaled temperature and precipitation time series as input to the hydrological model SWAT
suggested for both A2a and B2a emission scenarios. The model output shows that there may be an
annual increase in flow volume up to 35% for both emission scenarios in three benchmark periods
in the future. All seasons show an increase in flow volume for both A2a and B2a emission
scenarios for all time horizons. Potential evapotranspiration in the catchment also will increase
annually on average 3 - 15% for the 2020s and 7-25% for the 2050s and 2080s for both A2a and
B2a emissions scenarios.
Key words: Climate Change; Guder Sub-Basin; GCM; SDSM; SWAT; SWAT-CUP; GLUE
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Keywords
Climate Change, Guder Sub-Basin, GCM, SDSM, SWAT, SWAT-CUP, GLUE