Abstract:
Knowledge of the internal renewable water resources of a country is strategic information
which is needed for long-term planning of a nation’s water and food security, among many
other needs. New modeling tools allow this quantification with high spatial and temporal
resolution. In this study, Soil and Water Assessment Tool (SWAT) was used to calibrate and
validate flow and sediment yield at Erer river gauging station and predict the water and
sediment yield of Yahya Sherka watershed. Sensitivity analysis, model calibration and
validation were also performed to assess the model performance. Ten highly sensitive
parameters were identified of which curve number was the most sensitive one. The
coefficient of determination (R2) and Nash-Sutcliffe (ENS) was used to evaluate model
calibration and validation. The R2 values were 0.855 and 0.87, respectively, for the flow
during the calibration and validation periods. The respective R2 values for the monthly
sediment yield were 0.864 and 0.900. A good agreement between the measured and
simulated average monthly flows was also demonstrated by ENS values of 0.853 and
0.868, respectively, during the calibration and validation periods. The corresponding ENS
values for sediment yields were 0.80 and 0.90. In most instances, the simulated average
monthly flows and sediment yields were close to the average monthly measured values during
both the calibration and validation periods at Erer gauged station. The water and sediment
yield of Yahya Sherka watershed was quantified. After calibration and validation of the
model the mean annual simulated water and sediment yield of Yahya Sherka watershed
were estimated as 0.97Mm3
and 0.145 tons/ ha respectively. The SWAT model could be
effectively used to predict runoff and sediment yield in order to effectively design water
resource related development in absence of gauged information. In both case, for runoff and
sediment yield simulation, SWAT model has showed a strong predictive capacity from the
watershed. Therefore, the model can be used for simulating runoff and sediment from
ungauged watershed that having similar physiographic and climatic condition with Erer
watershed.
