A Flood Forecasting Model Based on Synthetic Unit Hydrograph of ITS-2

ITS-2 is a synthetic unit hydrograph (SUH) model developed at the Institut Teknologi Sepuluh Nopember (ITS) in 2017. The development of this model is intended to predict the potency of flood peak based on certain rainfall inputs in the watershed system, especially in an unmeasured watershed or measured watersheds with insufficient data. The high deviation that resulted from previous similar models had low performance in the tested watershed, also the reason this SUH model was developed. The main properties of this model are the accommodation of fractal parameters of the watershed, especially in peak time equations and a very simple single curve equation derived from the two-parameter Gamma Distribution. This paper intends to introduce the ITS-2 Model to estimate flood hydrographs in various watersheds in Indonesia. By introducing this model, it is expected to be able to obtain information from various users in Indonesia regarding the performance and validity of the model, so that improvements can be made in the future. Application in one watershed on the Island of Borneo, namely the Upper Telen Watershed in East Kalimantan Province, Indonesia, proves that this model shows a fairly good performance with a relatively low root mean square error (RMSE) and correlation coefficient (r) above 80%. However, testing on watersheds in various regions in Indonesia needs to be applied continuously to determine the reliability of the model.