mag

Malaysia Water Research Journal
for Skudai River was generated by using Automatic Sample Pump ISCO 6712
(Teledyne ISCO, 2012) that collected water level data every week. During high
flows, the sample nozzle pump was submerged at the bottom of the river to
determine an exact of total suspended solids had been collected. Subsequently,
after sufficient data have been collected, linear correlation analysis between
flow and total suspended solids were estimated.
The statistical analysis of hourly observed and simulated runoff were defined
using linear regression (coefficient of determination, R2), Nash-Sutcliffe efficiency
(ENs) and the relative error (Dv). Nash-Sutcliffe efficiency is given as:
where N is the number of observations during the simulated period, Oi and Si
are the observed and simulated values at each differences point i and OAvg is
the mean of the observed values.
ENS ranges from negative to infinity, with 1 denotes a perfect agreement
with observed data. Nash-Sutcliffe efficiency has been used in many researches
to determine model evaluation and considered as one of the best statistics for
evaluation of continuous hydrograph simulation programs (ASCE, 1993)
The coefficient of determination, denoted R2 and pronounced R squared, is
a number that indicates how well data fit a statistical model. It ranges from zero
to 1, with 1 is the perfect agreement between simulated and observed data. R2
is given by:
Where Oj is the observed flow at time step j, is the average observed flow
during the simulation period, Sj is the model-simulated flow at time step j and is
the average simulated flow at time step j.
The relative error (Dv) is calculated as:
Where Xm is the observed total runoff volume and Xs is the model-simulated
total runoff. The smaller the number of Dv gives the better result for simulation
and observation data. For a perfect model, Dv would be equal to zero.
RESULTS
124
Institut Penyelidikan Hidraulik Kebangsaan Malaysia (NAHRIM)
National Hydraulic Institute of Malaysia (NAHRIM)