Author(s): Hayata Yanagihara; So Kazama; Tsuyoshi Tada

Linked Author(s):

Keywords: Pluvial flood; Economic loss; High-floor house; Climate change; Adaptation measure

Abstract: This study evaluated the damage-mitigation effect of high-floor houses as an adaptation measure for pluvial floods in Japan. Several adaptation scenarios were set by varying the implementation area and height of highfloor houses. The implementation areas of high-floor houses were flooded areas above floor level due to pluvial flooding with return periods of 10 and 30 years in the baseline period. The heights of high-floor houses were 1 m, 2 m, and 3 m. The inundation depth caused by pluvial flooding based on extreme rainfall was calculated using a two-dimensional unsteady flow model. The flood damage cost was calculated by multiplying the asset value of the inundated land by the damage rate determined by the inundation depth. In inundation analysis, we set two inundation conditions focusing on the presence or absence of drainage to rivers. Extreme rainfall in future periods was estimated from the output values of five general circulation models. Then, the pluvial flood damage in future periods was estimated using these extreme rainfall data. The effect of high-floor houses was reflected in the damage cost calculations. In the late 21st century, it was estimated that the expected annual damage cost (EADC) under both inundation conditions could be reduced compared to the EADC in the baseline period by raising houses by 1 m or more under the RCP2.6 scenario and 2 m or more under the RCP8.5 scenario in the flooded areas above floor level with a return period of 30 years.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0309-cd

Year: 2023