Evaluation of flood damage reduction throughout Japan from adaptation measures taken under a range of emissions mitigation scenarios

Tao Yamamoto,Tsuyoshi Tada,So Kazama,Takeshi Yamashita,Hayata Yanagihara,Hiroyuki Takizawa,Yoshiya Touge

doi:10.1007/s10584-021-03081-5

Tao Yamamoto, Tsuyoshi Tada + Show 5 more

Open Access

https://doi.org/10.1007/s10584-021-03081-5

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Abstract

This study aimed to evaluate the impact of climate change on flood damage and the effects of mitigation measures and combinations of multiple adaptation measures in reducing flood damage. The inundation depth was calculated using a two-dimensional unsteady flow model. The flood damage cost was estimated from the unit evaluation value set for each land use and prefectures and the calculated inundation depth distribution. To estimate the flood damage in the near future and the late twenty-first century, five global climate models were used. These models provided daily precipitation, and the change of the extreme precipitation was calculated. In addition to the assessment of the impacts of climate change, certain adaptation measures (land-use control, piloti building, and improvement of flood control level) were discussed, and their effects on flood damage cost reduction were evaluated. In the case of the representative concentration pathway (RCP) 8.5 scenario, the damage cost in the late twenty-first century will increase to 57% of that in the late twentieth century. However, if mitigation measures were to be undertaken according to RCP2.6 standards, the increase of the flood damage cost will stop, and the increase of the flood damage cost will be 28% of that in the late twentieth century. By implementing adaptation measures in combination rather than individually, it is possible to keep the damage cost in the future period even below that in the late twentieth century. By implementing both mitigation and adaptation measures, it is possible to reduce the flood damage cost in the late twenty-first century to 69% of that in the late twentieth century.

Highlights

In recent years, society has been focusing on developing measures to cope with climate change caused by global warming
Using five global climate models (GCMs), the expected annual damage cost (EADC) caused by floods was estimated for the near future period around 2050 and for the late twenty-first century period around 2100
1) In the no adaptation scenario, the EADC in the near future is estimated to increase by 42% from the late twentieth century, with or without mitigation; in the late twenty-first century, it was estimated to increase by 57% in the RCP8.5 scenario, while it is limited to 28% in the RCP2.6 scenario

Summary

Introduction

Society has been focusing on developing measures to cope with climate change caused by global warming. In the Global Risk Report 2020 presented at the World Economic Forum Annual Meeting held in January 2020, extreme weather, major natural disasters, and failure of climate change mitigation and adaptation have been ranked high in the list of long-term risks that are likely to occur over 10 years (World Economic Forum 2020). According to the IPCC AR5 report, as the global average temperature rises, extreme precipitation is very likely to become stronger and more frequent in most of the mid-latitude land areas and moist tropical regions by the end of this century (IPCC 2013) Because this prediction suggests an increase in the frequency of heavy rainfall, an increase in the activity of tropical cyclones, and a rise in sea levels, it is essential to establish adaptation measures against water-related disasters, which are expected to increase in the future because of climate change

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