Nationwide Probabilistic Flood Discharge Dataset

This dataset provides estimates of flood peak discharges corresponding to various return periods across all river channels in Japan, including small- and medium-sized rivers, under present and future climate conditions (assuming global temperature increases of +2°C and +4°C).
From the 5-km mesh ensemble climate projections (d4PDF_5kmDDS_JP), approximately 3,000 to 5,000 heavy rainfall events were extracted for each region. These were used as input to the nationwide Rainfall-Runoff-Inundation (RRI) model, which represents Japan's topography at a 150-meter resolution. Flood discharges were simulated for all river reaches across Japan, and the results are compiled in this dataset.
At each river location, the top 72 discharge events were analyzed using extreme value statistics based on a non-annual (Peak-over-Threshold) series to estimate probabilistic flood peak discharges corresponding to arbitrary return periods of 10 years or more. In addition, the dataset includes the hydrographs and basin-averaged rainfall time series (hyetographs) of these 72 events used in the estimation, as well as the corresponding spatial rainfall distributions.