The extreme precipitation has occurred and caused severe flood disaster in smaller catchments in Japan. Limited studies evaluate predictability of water level by rainfall-runoff model for a small-to-medium catchments in Japan. This study evaluates predictability of water level in small catchments using Rainfall-Runoff-Inundation model and precipitation forecasts with 6-hour lead time. The flood forecast model is applied to Katsura river, Kyoto Prefecture, Japan. This study uses 2013 typhoon rainfall event in Kyoto. The results demonstrate that the model can predict water level in next 1 hours for 50km2 catchments and in next 2 hours for 50 km2 ~ 300 km2This study will further investigates the predictability of water level using several flood events caused by typhoon and frontal rainfall events