Search

The paper examines the nature of the linkage between climate change and the socio-economic adaptive strategies deployed at the metropolitan scale using an original methodology. A situated analysis of the Grenoble metropolitan system illustrates the struggle of the collective organization in keeping pace with the local climate evolution. This 'climate of bad timing' links the frequency of hydro-climatic extremes, the adaptive pace of territories and the concrete modalities of collective organization within the flood risk regime. To face these temporal challenges, there is an urgent need for developing localized transdisciplinary coalitions. In bridging science and policy, these coalitions would be positioned to co-produce robust and relevant climate information and devise sustainable strategies for the territory. Here, we suggest a more in-depth examination of the role of time in a commons perspective. [ABSTRACT FROM AUTHOR]

Abstract Earthquake damage and loss scenarios are considered as a powerful tool to help in the design of efficient seismic mitigation policies. Moreover, at a city scale, adequate urban planning may significantly contribute to improve resilience through requalification of inherited urban fabrics and/or appropriate land use. In this perspective, the present paper investigates what could be the optimal graphic representation of probable losses at urban scale, which be most relevant for seismic risk management. The goal is to provide urban planners with guidelines on how to combine the use of vulnerability index-based damage estimates and GIS tools, to identify urban fabrics that need requalification. The proposed methodology consists in starting from damage estimates at the individual building scale and using GIS (Geographic Information Systems) capacities to aggregate the expected damage on neighborhoods of increasing size, from blocks to large urban districts, in order to delimitate homogeneous urban zones. The criteria thus for choosing the optimal aggregation level are based on the need to obtain legible maps combining robust damage estimations – which implies statistics over a large enough number of buildings –, and a clear identification of the most vulnerable urban areas on which dedicated actions should be focused in priority. These methodologies are presented and tested on the example of the city of Oran (Algeria), and on the basis of a prior vulnerability study based on GNDT and RISK-UE vulnerability index approaches. The main outcome is the identification of different urban zones, which exhibit some homogeneity regarding both their average seismic response and their urban function. The most vulnerable urban fabrics require not only individual retrofitting measures at building scale; they also need urban requalification because it is more convenient to deal simultaneously with urban and safety considerations. Highlights • Individual buildings damages are aggregated to obtain a representative damage zone. • Aggregation increases the robustness of the results of the damage estimation. • A prioritization process of vulnerable urban fabrics has been suggested. • The most vulnerable urban fabrics require urban requalification. [ABSTRACT FROM AUTHOR]

The city of Oran is exposed to a significant seismic hazard, as almost all the northern Algeria territory, where numerous casualties and severe damage occurred in the last decades due to several moderate to large earthquakes. A mitigation policy should include the establishment of priorities to reduce the vulnerability of existing buildings based on the knowledge of the actual urban fabrics. The complexity of vulnerability assessment requires a gradual approach from the urban scale to the building scale. The study reported in this paper corresponds to the first step of such an approach, i.e., a preliminary study of the seismic vulnerability and expected damage within an urban district of the city of Oran, based on a non-dedicated data base from a building survey previously performed for other purposes. The main goals of this study are twofold: (1) an assessment of the degree of uncertainty and robustness of such results through a comparison of the results derived from different urban vulnerability methods (GNDT 2; RISK-UE LM1; and VULNERALP 2.0) and (2) an assessment of the actual level of seismic risk in the city of Oran. Cross-method comparisons and correlations highlight a satisfactory agreement between mean damage estimates at the urban scale, despite significant scattering at the single building scale, and uncertainty levels which vary significantly from one method to the other. For a given scenario, the three methods provide damage estimates lying within half an EMS damage degree of one another, with some systematic positive bias for VULNERALP and negative bias for RISK-UE LM1, especially for masonry buildings. The expected mean damage is very important for intensities 9 and 10, with an average damage grade around 3-4 for intensity 9 and 4-5 for intensity 10. The spatial distribution of damage systematically exhibits larger values in the northern, older, commercial area, than in the southern, more recent and more residential area, in relation to the building typology and the existence of several aggravating factors. Some areas of higher vulnerability / damage can be distinguished, which should receive particular attention for retrofitting priorities or urban planning decisions, also taking into account their cultural heritage value. [ABSTRACT FROM AUTHOR]