Abstract:
ABSTRACT
The study presents on the application of hydrological watershed models in the Blue Nile
basin to evaluate the sediment prediction capability of SWAT and PED-WM in the range
of scale of watershed. Watersheds were AnditTid (4.84km2),Temcha (410.09km2) and
Gumara(1270.75km2). Calibration and validation was carried out for both stream flow and
sediment load at the outlet, for sixteen years measured data 2000 to 2015considering the
warm-up, calibration and validation(2000, 2001-2010&2011-2015) respectively. Good
agreement between measured and simulated flow and sediment load were observed, which
was verified using both graphical technique and quantitative statistics. Model efficiency
criteria for SWAT model stream flow; the calibration of AnditTid, Temcha and Gumara
SWAT(NSE=0.70,0.62,0.64)and(NSE=0.91,0.75,0.89)andvalidation(NSE=0.84,0.65,0.68)
and(NSE=0.89,0.93,0.71) the daily and monthly time. Similarly; PED-WM for Gumara
(NSE=0.74,0.58,0.80)and(NSE=0.90,0.80,0.91)andvalidation(NSE=0.85,0.51,0.83)and(N
SE=0.94,0.57&0.94) in the daily and monthly time respectively. Similarly; SWAT model
sediment load calibration in AnditTid, Temcha and Gumara (NSE=0.68, 0.56, 0.63) and
(NSE=0.88, 0.65,0.78) and validation of the SWAT model (NSE=0.77,0.72,0.73) and
(NSE=0.92,0.86,0.85) in daily and monthly respectively. PED-WM sediment calibration
in AnditTid, Temcha and Gumara (NSE=0.73,0.75,0.81) and (NSE=0.90,0.82,0.83) and
validation (NSE=0.75,0.65,0.91)and(NSE=0.92,0.80,0.90) in the daily and monthly time
respectively. Difference in model behavior depends on runoff mechanism. SWAT model
the main direct runoff generation process is infiltration excess and could predict better
monthly discharge and sediment load than daily time step. In case of PED-WM saturation
excess is the main direct runoff process and could predict the maximum extent of runoff
generation area 6% (5% saturated and1% degraded). Generally, the output of this study it
will support planners and decision makers to take relevant soil and water conservation
measures and diminish the frightening soil loss and land degradation troubles in the Blue
Nile Basin, Ethiopia.
KEYWORDS: Hydrological Model, Blue Nile basin, Sediment Yield, SWAT & PED-W