To test the ability of the model to predict system
response, a graphical method (time series plot), and a
statistical measurement were used to evaluate the
model performance against the measured stream flow
data for the period of years (2000-2003) at four stream
gaging stations. Two statistical criteria were used including coefficient of determination (r2), and model
efficiency (E) [7]. The r2 represents the percentage
of the variance in the measured data that is explained
by the simulated data which varies between 0 and 1.
The E statistic indicates how close the plot of the
observed versus predicted values come to the 1:1 line.
If r2 and E values are close to zero, the model prediction
is considered unacceptable. In contrast, if these
values approach one, the model predictions become
highly accurate.