After the 2011 Great East Japan Earthquake and the tsunamis that caused widespread damage to coastal regions, artificial coastal defences including seawalls of 10-meters in height have been constructed in some coastlines in Japan. This reliance on traditional methods continues despite the growing awareness that grey based coastal infrastructure alone does not offer enough protection against tsunami such as that seen in 2011. In addition to this, the Japanese national and municipal governments have been odds with local people who wish to conserve coastal ecosystems and better coexist with the ocean. Historically, Pinus thunbergii has been planted along coasts in Japan, and these coastal forests have crucial roles in not only mitigating the velocity of tsunami and trapping debris, but also, providing the natural habitats for fauna and flora as well as granting authentic and recreational benefits for people. However, purely green measures such as coastal forests also have the limitations against cataclysmic waves. Concurrently, coastal areas are bearing the brunt of both seal level rise and the further increasing likelihood of extreme events (i.e. storm surges and typhoons). In tackling these issues, hybrid infrastructure – which combines grey and green components – has received small but growing interest.
Thus, our study focused on 1) clarifying people’s preference of coastal functions including ecosystem services, such as species richness, landscape, recreational services and disaster risk reduction, and on 2) revealing people’s preference of hybrid infrastructure in terms of additional seawalls’ height with intensity and ecosystem services. In order to inquire into these areas, an online survey – intended for people who live within 50km from the coastline across Japan – was administered, and then we analyzed it using the economic approach.
Results/Conclusions
Overall, the results of this study point to increased demands of both grey (seawalls) and green (coastal forests) coastal defences, with respondents seeking to combine ecological countermeasures alongside artificial structures. Moreover, auxiliary data on the risk perception of tsunamis and sea level rise, of which the former is unpredictable and likely to cause huge damage once it occurs though the latter is comparatively predictable but it has long-term influences on coastal communities. It is hoped that this studies will help develop understanding on which multi-disciplinary responses (e.g., engineers and ecologists) can strive to improve coastal defences and make decision about coastal planning both in Japan and around the world.