Urban form planning and tsunami risk vulnerability: Analysis of 12 Chilean coastal cities

Abstract

Urban form has a significant impact on risk. Spatial planning instruments can optimize urban form in areas exposed to hazards. This work discusses how urban planning instruments, specifically Communal Regulatory Plans (CRP), affect vulnerability to the risk of tsunami inundation in Chilean coastal cities. We analyze urban form and address exposure, susceptibility, and response capacity parameters. Exposure is evaluated by comparing existing and planned densities and to what extent planned risk areas coincide with inundation zones. We analyze existing critical facilities and land uses permitted by the CRP in inundation zones to evaluate susceptibility. We explore response capacity through the street network connectivity and green areas outside the inundation zone and how CRPs influence the structuring of new roads and new green spaces.
We found that CRPs do not hold the sufficient capacity to incorporate and manage the tsunami inundation risk adequately. The planning scenario leads to a systematic increase in vulnerability as cities develop in exposed areas. We suggest strengthening CRPs capacities to prevent the construction and reconstruction of areas affected by tsunamis, reinforcing the urban fabric´s potential for evacuation, and strengthening joint work between municipal urban planning and disaster risk management departments, among other recommendations.

Spatio-Temporal Analysis on Land Use/Land Cover Change in Banda Aceh: A Preliminary Study of Disaster Resilience

“…One primary aspect of this alignment involves the consideration of disaster-prone areas within a city's urbanization plan. When development plans disregard or inadequately address such areas, the result can be increased vulnerability to disasters [21]. For instance, if development occurs in tsunami-prone city without adequate urban form, the likelihood of tsunami-induced damages rises significantly.…”

Assessing the Role of Land-Use Planning in Near Future Climate-Driven Scenarios in Chilean Coastal Cities

“…For the selected municipalities we conducted a content analysis to examine how CRPs relate to the "presumed exposure analysis" (Figure 2a) and the refined "hazard-exposure analysis" (Figure 2b). We examined five urban dimensions previously used to understand how CRPs relate to risk analysis [36], namely, population density, land uses, risk areas, location of critical facilities, and urban wetlands. We carried out this analysis using ArcMap 10.4.1 to compile, geo-reference, and post-process the information, using open-source georeferenced data collected from governmental sources (Table 1).…”

“…Since the approval of most of these CRPs, there have been significant changes in the legal and political frame of urban planning, the patterns of urban and territorial development, and the climate context. While it is mandatory to Chilean municipalities to update their CRPs every 10 years, the country's mean is 14 years, coastal cities have planning schemes that are 17 years old on average [36], and the mean age of the analyzed CRPs is 22.5 years.…”