Inundation Analysis of the Oda River Basin in Japan during the Flood Event of 6–7 July 2018 Utilizing Local and Global Hydrographic Data

Abstract

During the first week of July 2018, widespread flooding caused extensive damage across several river basins in western Japan. Among the affected basins were the Mabicho district of Kurashiki city in the lower part of the Oda river basin of the Okayama prefecture. An analysis of such a historical flood event can provide useful input for proper water resources management. Therefore, to improve our understanding of the flood inundation profile over the Oda river basin during the period of intense rainfall from 5–8 July 2018, the Rainfall-Runoff-Inundation (RRI) model was used, with radar rainfall data from the Japan Meteorological Agency (JMA) as the input. River geometries—width, depth, and embankments—of the Oda river were generated and applied in the simulation. Our results show that the Mabicho district flooding was due to a backwater effect and bursting embankments along the Oda River. The model setup was then redesigned, taking into account these factors. The simulated maximum flood-affected areas were then compared with data from the Japanese Geospatial Information Authority (GSI), which showed that the maximum flood inundation areas estimated by the RRI model and the GSI flood-affected area matched closely. River geometries were extracted from a high-resolution digital elevation model (DEM), combined with coarser resolution DEM data (global data), and then utilized to perform a hydrological simulation of the Oda river basin under the scenarios of backwater effect and embankment failure. While this approach produced a successful outcome in this study, this is a case study for a single river basin in Japan. However, the fact that these results yielded valid information on the extent of flood inundation over the flood-affected area suggests that such an approach could be applicable to any river basin.

Developing Flood Risk Zones during an Extreme Rain Event from the Perspective of Social Insurance Management

“…To achieve the objectives of this study, various methods were employed using the data discussed in the previous section. The study framework was divided into two main steps: the first involved a hydrological simulation [11][12][13][36][37][38][39][40] and the second focused on developing flood risk using the analytic hierarchy process (AHP). This classic approach has been used in many studies [16,20,23,25,26,28].…”

“…Hydrological modeling is integral to understanding flood processes in various river basins. As a result, numerous studies have focused on hydrological simulations of floodaffected river basins during extreme rainfall events, with a particular emphasis on the inundation extent [11][12][13][36][37][38][39][40]. Different types of hydrological models are widely available, including HEC-HMS [41], VIC [42], and TOPMODEL [43], among others.…”

“…Japan has experienced frequent extreme rain events and the associated floods in recent years [8][9][10][11][12][13][14][15], leading to property damage and loss of life, which is becoming increasingly common every year. Catastrophic flooding occurred in the Kanto region in 2015 [10], the Kyushu region in 2017 [11], the western region of Japan in 2018 [12], the central northern region of Japan in 2019 [13], and recent flood events occurred in the Kyushu region in July 2020 [14]. These events all caused substantial loss of life and property damage [15].…”

River discharge prediction for ungauged mountainous river basins during heavy rain events based on seismic noise data

“…The RRI is a two-dimensional model that has the advantage of simultaneously modeling runoff and flood inundation (Sayama et al 2012(Sayama et al , 2020P.C. et al 2020a, 2020bNguyen et al 2021). This model is applicable to rainfall-runoff analysis and inundation profiling in each grid of a river basin.…”

Urban Flood Analysis in Ungauged Drainage Basin Using Short-Term and High-Resolution Remotely Sensed Rainfall Records

“…In recent years, it has become popular to comprehensively analyze floods by coupling remote sensing rainfall data and hydrological models, which solves the shortages of high spatialtemporal resolution rainfall data. For example, Shakti et al [36] combined remote sensing rainfall data and a distributed hydrological model to analyze inundation. Komi et al [37] have shown that using relatively rough spatial resolution remote sensing data as inputs to the distributed hydrological model can also roughly predict the flood range in Africa, where topographic and hydrological data are scarce.…”