HEC-HMS HYDROLOGICAL MODELLING FOR RUNOFF ESTIMATION IN CAMERON HIGHLANDS, MALAYSIA

Abstract

In water resources and more specifically in hydrology, the application of mathematical models to represent the hydrological cycle process is crucial. This is the reason why the hydrological concepts are expressed in mathematical language to represent the corresponding behavior observed in the nature. The current research targeted to develop a hydrological model using HEC-HMS model version 4.7.1 for runoff estimation in Cameron Highlands, Pahang, Malaysia. The Geographic Information System (GIS) was utilized to identify the geometric and hydrologist parameters. The Soil Conservation Service-Curve Number (SCS-CN) Method was adopted to estimate the rainfall losses while the Soil Conservation Service-Curve Number (SCSCN) Method was used to transform the excess rainfall into a direct runoff hydrograph. Muskingum Model was adopted for routing the total runoff from the outlet of the sub-basin to the outlet of the total basin. Model calibration was achieved using different sets of data (CN, Lag time and Muskingum K) in which the data used was for seven years (2000 to 2007). Results of model calibration showed very good fit between the simulated and observed data based on Coefficient of determination (R 2) = 0.9, Nash-sutcliffe Efficiency = 0.92, Root Mean Square Error = 0.1 and the Percent Bias = 0.77%. The model validation was accomplished based on data for couple of years (2007 to 2009) and it is indicated there is a very good matching between the simulated and observed hydrograph. Eventually, based on what have been presented earlier, it can be concluded that the model can be utilized for the Cameron Highland Watershed.