Nhu Y Nguyen, Yutaka Ichikawa, Hiroshi Ishidaira
Received 2015/10/29, Accepted 2016/02/17, Published 2016/03/24

Nhu Y Nguyen1), Yutaka Ichikawa2), Hiroshi Ishidaira1)

1) Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi
2) Graduate School of Engineering, Kyoto University

Inundation depth (or level) is the most basic information for flood risk assessment; however, its mapping suffers from lack of in situ data in many cases. The aim of this study is to propose a new method for estimating inundation depth and spatially distributed water level for a local-scale pluvial flood using a combination of flood extent information derived from remote sensing imagery and hydrodynamic simulations. The study assumes the location of the inundation area given by the remote sensing imagery is mostly, but not completely, reliable. The estimation error of ground surface area wetted by inundation water body (wetted area) is used as an index to determine the most likely distribution of inundation depth. The proposed method was applied to two study areas to examine the performance of the method for different topographic characteristics. It showed promising results with an estimation precision of 0.02 to 0.17 m. An additional experiment suggested that water level could not be correctly estimated without flood extent information, complementing errors of the ground elevation data, and furthermore, using different topographic datasets revealed that the performance was highly influenced by the ground elevation data.

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