Flooding in Oda River Basin during Torrential Rainfall Event in July 2018

  • Shakti P. C. National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan
  • Hideyuki Kamimera National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan

Abstract

Extreme rainfall events cause severe flooding and/or landslides almost every summer in Japan. It seems that the frequency of such events and induced human/economic losses has increased in recent years. A torrential rainfall event in early July 2018 caused severe flooding in many river basins over Hiroshima and Okayama Prefectures of western Japan and resulted a number of fatalities and serious damage to property. One of them is the Oda river basin (about 498 km2), which was severely affected by the flood during the event. Different types of observation systems were used to measure or estimate rainfall for this event. Comparison of radar and satellite-based rainfall shows a good agreement with the rain gauge observations of the entire period. Basin-mean total rainfall from Japan Meteorological Agency’s analyzed radar rainfall (RADJ), Water and Disaster Management Bureau’s radar rainfall (RADW), Automated Meteorological Data Acquisition System (AMeDAS), and satellite-based rainfall data (GSMaP) were about 314, 322, 357 and 304 mm during July 5–7 2018. In this study, we applied Rainfall–Runoff–Inundation (RRI) to acquire a detailed understanding of flood processes in the Oda river basin. All the available rainfall data including different spatial resolution of hydrographic features were considered as the main input data in the model separately. Gridded flow and map of the possible maximum flood depth across the basins were generated and validated. Simulated results based on high resolution topographic data are more closely aligned with observed data. It is also found that the maximum flood inundation areas estimated by the RRI model using radar rainfall data appeared somewhat closer with the extent of flood-affected areas from the model with data of the Japanese Geospatial Information Authority (GSI) over the Mabi city. It is believed that modelled results can be used an important reference in the disaster mitigation and that they may be useful for further studies.

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Author Biographies

Shakti P. C.

National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan

Hideyuki Kamimera

National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan

Published In
Vol 23 No 6, Nov 30, 2019
How to Cite
[1]
S. P. C. and H. Kamimera, “Flooding in Oda River Basin during Torrential Rainfall Event in July 2018”, Eng. J., vol. 23, no. 6, pp. 477-485, Nov. 2019.