Comparison of flood hydrograph prediction between synthetic unit hydrograph methods and rain-on-grid model for Katulampa watershed, Indonesia

In this paper, 6 synthetic unit hydrograph (SUH) methods, namely Snyder, SCS, GAMA-1, ITB-1, ITB-2, and Nakayasu, were compared against a rain-on-grid model (HEC-RAS) for flood hydrograph prediction in the Katulampa watershed, Indonesia. HEC-RAS was used with an open-access, ~30 m resolution digital elevation model (DEM), i.e. the Advanced Land Observing Satellite (ALOS). The relative error of the hydrograph results (peak discharge and time-to-peak) were compared with the observed data, while the errors in the hydrograph’s shape were detected using the Root Mean Square Error and Pearson Product Moment Correlation. We found that HEC-RAS could predict the flood hydrograph significantly more accurately than the SUH methods, yielding the value of 1.98 m3 /s and the value of 0.93. This study remains an interesting example of how modern computational tool can improve the runoff prediction of conventional SUH methods.