Abstract:
Climate change is exacerbating the frequency and severity of floods in catchment areas,
leading to increased inundation and posing significant challenges for flow predicting. The
impact of climate change on flood inundation and flow forecasting in catchment areas,
highlighting the need for accurate modeling techniques such as HEC-RAS to assess flood
risk, design resilient infrastructure, and develop effective emergency response plans. The
study emphasizes the importance of integrating climate change projections into flood
modeling to enhance preparedness and adaptation strategies in the face of a changing
climate. This study aims to develop flood forecasting and inundation mapping under
climate change for the Dijo River basin in the Rift Valley region of Amba Alage, Ethiopia.
To simulate flood patterns and map potential inundation areas hydrological and hydraulic
modeling for calibration and validation of observed flow to simulated flow, Improved
CMIP6 models for better data assimilation methods, accurate and consistent projections
of how flood inundation will be affected by climate change under the SSP2-4.5 and SSP5
8.5 scenarios for the baseline (1985-2014), mid-term (2041-2070), and long-term (2071
2100) cycles of the three climate models were used. Also, the General Extreme Value
method was used to analyze the frequency of floods under both scenarios of SSP2-4.5 and
SSP5-8.5 for 50 and 100-year return periods. The results of performance parameters R2 =
0.65, Pbias = 6.5, RMSE = 0.39, and NSE. = 0.65 for calibration and the R2 = 0.69, Pbias
=7.4, RMSE = 0.41, and NSE. = 0.69 for validation. The peak flow of 50 and 100-year
return periods in the long-term period under SSP2-4.5, and SSP5-8.5 respectively are
132.44, 154.32, 149.66, and 165.35m3/s. The flood inundation areas of 50 and 100-year
return periods in the long-term period under SSP2-4.5, and SSP5-8.5 respectively are 83,
88, 90, and 94 ha. The maximum average flood depths of 50 and 100-year return periods
in the long-term period under SSP2-4.5, and SSP5-8.5 respectively are 2.88, 3.12, 2.96,
and 3.2 m. The responsible body deal with the remedial measures to control flood
inundation under various climate scenarios, and also, the repairing and increasing the
height of the existing earthen dykes, construction of new dykes and levees at the Chefe
agricultural area, afforestation from the upper watershed of the Dijo River.
