Abstract:
In Ethiopia, there are large numbers of hydrological modeling works have been
conducted in different basins under different climate, land use, soil, geology. The applied
models have different structure to simulate discharge. Their ability in simulating
discharge in a comparison approach has not yet been explored. Thus conducting
comparative analyses of models and identifying better models which represent realistic
simulation is important for proper development and management of water resource for the
cathment. The main objective of this study was to compare HBV light semi distributed
and SWAT models in predicting streamflow in the Geba catchment upper Tekeze basin.
The various modelling procedure (i.e input data, sensitivity analsis, calibration, validation
and uncertainty assessment) were employed to test the models ability in predicting the
discharge at the outlet of Geba catchment. However, to have better understanding of
model parameter performance, sensitivity analysis of model parameters were performed
manually by trial and error procedure. The results shows that K2 , MAXBAS , BETA are
more sensitive than other model parameters in HBV light model and CN2, GWQMN and
SOL_AWC are more sensitive parameters in case of SWAT. The calibration results of
HBV light and SWAT as evaluated by E
NS
, R
2
and PBIAS are 0.70, 0.71 and 0.73, 0.81, 11%
respectively. Moreover, an E
NS
, R
2
and PBIAS of 0.71, 0.72 and 0.72, 0.72, 4.1%
were obtained during validation Period for HBV light and SWAT models respectively.
From the uncertainity plot for HBV light most of the simulated flow are inside the 95PPU
with high predictive uncertainity band as comparsion with the SWAT CUP uncertainity
analysis by SUFI 2 and from the uncertainity plot in SWAT model most of the simulated
hydrograph is outside the upper and lower band and less predictive uncertainiy. These
mentioned results depicted that both models are well reasonably simulated the discharge
of Geba catchment. And from uncertainity and identifiability of parameter applying HBV
light model could be effective in simulation of runoff for sustainable water resources
management and development in the watershed runoff by considering sensitivity, model
performance, parameter identification and uncertainity analysis.
