Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan

ABSTRACT The authors present an attempt to reproduce a flash flood in the steep mountainous Myohoujigawa River, Japan, using a physics‐based distributed rainfall‐runoff/flood‐inundation model (DRRFI). The Myohoujigawa River is located in Kobe city. The length is 6.975 km and the area is 11.81 km2. T...

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Main Authors: Kenichiro Kobayashi, Atsushi Tamura, Riku Misato, Ichiro Fujita, Takaya Okuyama, Genki Kumano, Le Duc
Format: Article
Language:English
Published: Wiley 2025-06-01
Series:Journal of Flood Risk Management
Subjects:
Online Access:https://doi.org/10.1111/jfr3.70076
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author Kenichiro Kobayashi
Atsushi Tamura
Riku Misato
Ichiro Fujita
Takaya Okuyama
Genki Kumano
Le Duc
author_facet Kenichiro Kobayashi
Atsushi Tamura
Riku Misato
Ichiro Fujita
Takaya Okuyama
Genki Kumano
Le Duc
author_sort Kenichiro Kobayashi
collection DOAJ
description ABSTRACT The authors present an attempt to reproduce a flash flood in the steep mountainous Myohoujigawa River, Japan, using a physics‐based distributed rainfall‐runoff/flood‐inundation model (DRRFI). The Myohoujigawa River is located in Kobe city. The length is 6.975 km and the area is 11.81 km2. The authors aimed to simulate a 4 m rise in the water level within 40 min in the catchment. Man‐made open‐channel rainwater drainages were added to the river network which could collect more rainwater faster. Likewise, the flux difference splitting (FDS) scheme was used for 1D dynamic wave modeling of steep river flow because it can simulate sub‐ and super‐critical flow regimes. Moreover, the X‐band rainfall data of 250 m and 1 min spatiotemporal resolution, currently the highest‐resolution product in Japan, served as input for the rainfall‐runoff‐inundation model. Consequently, a level of reproducibility was achieved via runoff simulation using the X‐band rainfall data. Subsequently, 21 forecast ensemble rainfalls under the operation of the Japan Meteorological Agency were used for the feasibility study of ensemble flood forecasting. This ensemble flood simulation aimed to determine that the 5 km and 1 h spatiotemporal resolution of the ensemble rainfall currently best product available to the general public in Japan were sufficient to reproduce the flash flood that occurred within 40 min. The 21 ensemble flood simulations exhibited qualitatively acceptable results as the water level rise timings are similar; however, quantitatively the simulated water levels were lower than those of the observed water.
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spelling doaj-art-72ec8d6c0eec43c5a999471e6a2bc89c2025-08-20T02:22:06ZengWileyJournal of Flood Risk Management1753-318X2025-06-01182n/an/a10.1111/jfr3.70076Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in JapanKenichiro Kobayashi0Atsushi Tamura1Riku Misato2Ichiro Fujita3Takaya Okuyama4Genki Kumano5Le Duc6Graduate School of Science and Engineering Saitama University Saitama JapanGraduate School of Civil Engineering, Faculty of Engineering Kobe University Kobe JapanGraduate School of Civil Engineering, Faculty of Engineering Kobe University Kobe JapanGraduate School of Civil Engineering, Faculty of Engineering Kobe University Kobe JapanGraduate School of Civil Engineering, Faculty of Engineering Kobe University Kobe JapanGraduate School of Civil Engineering, Faculty of Engineering Kobe University Kobe JapanMeteorological Research Institute Tsukuba JapanABSTRACT The authors present an attempt to reproduce a flash flood in the steep mountainous Myohoujigawa River, Japan, using a physics‐based distributed rainfall‐runoff/flood‐inundation model (DRRFI). The Myohoujigawa River is located in Kobe city. The length is 6.975 km and the area is 11.81 km2. The authors aimed to simulate a 4 m rise in the water level within 40 min in the catchment. Man‐made open‐channel rainwater drainages were added to the river network which could collect more rainwater faster. Likewise, the flux difference splitting (FDS) scheme was used for 1D dynamic wave modeling of steep river flow because it can simulate sub‐ and super‐critical flow regimes. Moreover, the X‐band rainfall data of 250 m and 1 min spatiotemporal resolution, currently the highest‐resolution product in Japan, served as input for the rainfall‐runoff‐inundation model. Consequently, a level of reproducibility was achieved via runoff simulation using the X‐band rainfall data. Subsequently, 21 forecast ensemble rainfalls under the operation of the Japan Meteorological Agency were used for the feasibility study of ensemble flood forecasting. This ensemble flood simulation aimed to determine that the 5 km and 1 h spatiotemporal resolution of the ensemble rainfall currently best product available to the general public in Japan were sufficient to reproduce the flash flood that occurred within 40 min. The 21 ensemble flood simulations exhibited qualitatively acceptable results as the water level rise timings are similar; however, quantitatively the simulated water levels were lower than those of the observed water.https://doi.org/10.1111/jfr3.70076ensemble predictionrainfall‐runoff‐inundation modelrainwater drainageSpace Time Image Velocimetry (STIV)steep mountainous riverX‐band rainfall
spellingShingle Kenichiro Kobayashi
Atsushi Tamura
Riku Misato
Ichiro Fujita
Takaya Okuyama
Genki Kumano
Le Duc
Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
Journal of Flood Risk Management
ensemble prediction
rainfall‐runoff‐inundation model
rainwater drainage
Space Time Image Velocimetry (STIV)
steep mountainous river
X‐band rainfall
title Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
title_full Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
title_fullStr Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
title_full_unstemmed Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
title_short Reproducing a Flash Flood Using the Rainfall‐Runoff‐Inundation Model for the Myohoujigawa River Basin in Japan
title_sort reproducing a flash flood using the rainfall runoff inundation model for the myohoujigawa river basin in japan
topic ensemble prediction
rainfall‐runoff‐inundation model
rainwater drainage
Space Time Image Velocimetry (STIV)
steep mountainous river
X‐band rainfall
url https://doi.org/10.1111/jfr3.70076
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