Prediction of Flooding Area in Batang Sinamar River Basin Based on Design Return Period Simulation by Using Rainfall Runoff Inundation Model

[摘要] Lima Puluh Kota Regency in West Sumatera Province is one of the regencies in Indonesia that has had a flood problem every year in the last decade. In the case of such large-scale flooding, it is important to classify the hazard zone for efficiency of the flood mitigation. In this paper, the Rainfall-Runoff-Inundation (RRI) model is applied to the Batang Sinamar River Basin in order to predict the widespread inundation, where both rainfall-runoff from surrounding mountain and rainfall on flood plain contributes to the flood event. Flood simulation was conducted by using a nationally available dataset, high resolution digital surface model, and rainfall ground station data. The simulation was calibrated with discharge observation data in Batang Sinamar, and provides a good result with the Nash–Sutcliffe Efficiency index and correlation value of 0.768 and 0.908, respectively. The result of the simulation using 10-year and 25-year return, showed the increasing discharge by 15.72% from 406.77 m3/s to 470.74 m3/s. Furthermore, the average peak of inundation water level increased from less than 1.5 m to more than 1.5 m. Based on these results, it can be concluded that the model can predict the potential inundation area in the Batang Sinamar River Basin in Lima Puluh Kota Regency.

[关键词] rainfall runoff inundation model;Batang Sinamar River Basin;flood hazard