Abstract
The main aim in this research is comparison the parameters of some storm events in the watershed using two loss models in Unit hydrograph method by HEC-HMS. SCS Curve Number and Green-Ampt methods by developing loss model as a major component in runoff and flood modeling. The study is conducted in the Kuala Lumpurwatershed with674 km2 area located in Klang basin inMalaysia. The catchment delineation is generated for the Klang watershed to get sub-watershed parameters by using HEC-GeoHMS extension in ARCGIS. Then all the necessary parameters are assigned to the models applied in this study to run the runoff and flood model. The results showed that there was no significant difference between the SCS-CN and Green-Ampt loss method applied in the Klang watershed. Estimated direct runoff and Peak discharge (r = 0.98) indicates a statistically positive correlations between the results of the study. And also it has been attempted to use objective functions in HEC-HMS (percent error peaks and percent error volume) to classify the methods. The selection of best method is on the base of considering least difference between the results of simulation to observed events in hydrographs so that it can address which model is suit for runoff-flood simulation in Klang watershed. Results showed that SCS CN and Green-Ampt methods, in three events by fitting with percent error in peak and percent error in volume had no significant difference.
Highlights
Usual methods of runoff and flooding estimation are costly, time consuming along with error because of having various variables contribute in the watershed
The results showed that there was no significant difference between the SCS-CN and Green-Ampt loss method applied in the Klang watershed
There are various methods to simulate surface runoff and flooding by using different loss model methods in HECHMS which some of them consist of the SCS Curve Number model [1], CASC2D [2], TOPMODEL [3], GIUH [4], University of British Columbia Watershed Model (UBCWM) and Geomorphological Instantaneous Unit Hydrograph (GIUH)
Summary
Usual methods of runoff and flooding estimation are costly, time consuming along with error because of having various variables contribute in the watershed. Many studies have been conducted by [5,6,7,8,9] who have applied the GIS tools to estimate runoff CN value to make an empirical runoff estimation and many researches was implemented by [10,11,12,13] to demonstrate SCS application in hydrological studies. This method is based on a rainfall-runoff model that was created to quantify direct runoff. To estimate the direct runoff (excess rainfall) the major components of a watershed which contribute to runoff are the data such as land use, soil data and antecedent moisture conditions (AMCs) which are designed to estimate the loss and runoff volume [15]
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