Abstract:
Modelling climate change impact is very important to reduce the crisis behind food
security, drought, and loss of energy sectors. The impact on streamflow and hydrological
components due to climate change was aimed to investigate by the SWAT model for this
study. Two regional climate models (RCM) were selected according to their performance
to calibrate and validate the streamflow. The Regional Climate Models’ performance in
simulation of flow and the hydrological cycle was evaluated by statistical performance
criteria. Digital elevation model (DEM), land use land cover and soil map, and streamflow
data were collected and used as raw input for the model. Bias correction was made by
using power transformation and variance scaling method for RCM against observed data.
The result simulated with RACMO22T was best with (PBIAS = 0.23, NSE = 0.84, R2 = 0.79) for
calibration, (PBIAS = 0.11, NSE = 0.88, R2 = 0.81) for validation. RCA4 model underper formed in simulating streamflow compared to RACMO22T with (PBIAS = 0.28, NSE = 0.78,
R2 = 0.74) and (PBIAS = 0.18, NSE = 0.85, R2 = 0.78) for calibration and validation of the
models respectively. The streamflow was projected and shows a slightly increasing
trend respectively with 13.8 and 21.3 % for the 2030s and 2050s simulation years. But
in the 2080s simulation periods, the simulated streamflow indicates a decreasing trend
under representative concentration pathways (RCP4.5) by 12.5%. The overall result indi cates both streamflow and runoff show a decreasing pattern in the end of this century
under both scenarios. The spatial variability of hydrological components which
contributes to streamflow was dependent on the subbasin characteristics. Furthermore,
the simulated groundwater recharge (GW_Q), rainfall, water yields (WYLD), surface runoff
(SUR_Q) and evapotranspiration (ET) were decreased by 4%, 17.7%, 20.8%, 27.7%, and
8.6% respectively for the baseline period.
