Assessing the impact of road segment obstruction on accessibility of critical services in case of a hazard

Abstract

Abstract. Development of hazard maps is one of the measures promoted by the international community to reduce risk. Hazard maps provide information about the probability of given areas to be affected by one or several hazards. As such they are useful tools to evaluate risk and support the development of safe policies. So far studies combining hazard mapping with accessibility to services are few. In hazardous environments, accessibility of the population to strategic infrastructure is important because emergency services and goods will principally be offered at or provided from these locations. If a road segment is blocked by a hazard, accessibility to services may be affected, or worse, people may be completely disconnected from specific services. The importance of each road segment in the transport network as a connecting element enabling access to relevant services is therefore critical information for the authorities. In this study, we propose a new application of hazard mapping which aims to define the importance of each road segment in the accessibility to services, taking into account the probability of being affected by a hazard. By iteratively removing one segment after the other from the road network, changes in accessibility to critical infrastructure are evaluated. Two metrics of road segment importance considering the population affected and the hazard probability are calculated for each segment: a road accessibility risk metric and a users' path vulnerability metric. Visualization of these road metrics is a useful way of valuing hazard maps and may help to support discussions about the development of new infrastructure, road capacity increase and maintenance of existing infrastructures, and evacuation procedures.

Lava flow crises in inhabited areas part I: lessons learned and research gaps related to effusive, basaltic eruptions

“…Although Karthala has affected settlements less frequently than other case studies presented here, Grande Comore has been the focus of multiple studies on lava flow hazard and community's understanding of it (e.g. Mossoux et al 2019).…”

“…This eruption is celebrated annually on 5 April. Bachelery et al (2016), , Mossoux et al (2019), Krafft (1982) island's population (Table 10). Miyakejima is monitored by the Geological Society of Japan.…”

“…Since, additional work on using GIS to support lava flow modelling and impact assessments has been conducted (e.g. Davoine and Saint-Marc 2016;Mossoux et al 2019), and there has been extensive work about how lava flow models can be used after recovery (e.g. Tarquini and Favalli 2016;Scifoni et al 2010).…”

Preface: Natural hazard impacts on technological systems and infrastructures

“…The study areas vary from national and interregional scales in North America (Jeong et al, 2019), Brazil (Sayão et al, 2020), Chili, Japan (Williams et al, 2020), and the Russian Federation (Frolova et al, 2020;Petrova, 2020) to regional and local scales in Normandy, France (Braud et al, 2020), the province of Salamanca in Spain (Fluixá-Sanmartín et al, 2019), Bucharest in Romania (Toma-Danila et al, 2020), Hubei Province in China (Chen et al, 2019), and Ngazidja Island, NW of Madagascar (Mossoux et al, 2019).…”

“…Since more involvement of the humanities is needed in natural disaster research and the topic of the special issue builds on the "natural hazards and society" section of the EGU, the paper is a good enrichment of the SI. Frolova et al (2020) consider instead the application of an impact database for the example of Russia, as in Petrova (2020). The database is available upon special request for international projects, thus constituting an infrastructure itself for later projects.…”