Urban Risks

URiS - ISSN 2516-1857 - © ISTE Ltd

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Climate change is shaking up research agendas and urban planning priorities. A number of events, including floods and heatwaves, are disrupting metropolitan areas. Urban redevelopment to meet these challenges is costly and takes time. Numerical simulation is a great tool for studying urban development scenarios and the effectiveness of development solutions. Numerical models of the urban climate exist and are gradually being improved by the scientific community. These models are parameterised, among other things, by geographical data describing mineral surfaces (buildings, asphalt floors), non-mineral surfaces (water surfaces, herbaceous soils, bare permeable soils) and tree canopies. In this article we study the suitability of existing topographic data for parameterising climate models. We begin by recalling the importance of database specifications for understanding the gap between the real world and the content of databases. We then describe strategies for constructing land cover data suitable for studying the urban climate using national reference systems and in the absence of such data. Finally, we consider the potential contribution of very large-scale data, such as BIM, to the study of urban climates. In conclusion, we propose an improvement in the specifications of national geodatabases to better meet the needs of urban planning in the context of climate change.

Today, urban climate diagnostic tools can be useful to local authorities and cities: they provide input for urban planning and development project design at different spatial scales, in a context of mitigating both global climate change and local climate heat peaks. In the following paper, we identify and list diagnostic tools, and mainly focus on geoclimatic ones. The latter have the particularity of requiring geomatics and geographic data to provide useful outputs for diagnosing overheating in cities. A classification of these tools is presented, based on four criteria. The first criteria is based on how the urban fabric is considered by each of the tools: simplified or detailed. The second criteria is the type of output produced by the software: it contains physical quantities or qualitative information (e.g. shadow or sunlit). The third criteria is relative to the choice of the problem-solving approach: physical vs statistical? The last criteria is what type of physics the software tool addresses (air temperature, wind, radiation, etc.). Finally, tools are sorted according to this classification and their relation to geomatics further described. It emerges that each tool has been developed for a particular need and from a specific point of view. This point of view will also help to explain the strengths, weaknesses and simplifications of each tool. Lastly, it highlights areas where software development, or even model development, require the attention of the GIS sci-ences.

The urban heat island and urban air pollution, major health risks in cities, can be measured by networks of fixed stations or mobile measurements in urban environments. Protocols have been set up to ensure that climate and air pollution issues are representative at different spatial and temporal scales. The aim of this article is to present the existing measurement networks, the protocols implemented in French research, and the spatial representations of the data derived from these measurements. This overview provides an insight into the scientific and technical issues involved in setting up climate and air pollution measurements.

From the early stages of industrialization in Europe, America or Japan, the living standards of populations have drastically improved thanks to explorations, the use of coal, steel, as well as of nuclear or nanotechnologies, although such progress is increasingly called into question. However, would these improvements have been possible had their initiators been aware of the human and environmental consequences right from the beginning? Nowadays, companies boasting ecological values attempt to limit the consequences of risks by regulating or even prohibiting any action deemed dangerous, as illustrated by the "precautionary principle". In this context, this paper offers a reflection on the importance given to geography when it comes to dealing with the notion of risk and accepting it, arguing for a transdisciplinary approach, thus integrating perceptions and representations of the risk concept into the study of territories.

This paper first argues that the driving force behind the aggregation of human settlement, throughout the centuries, has been the ever-increasing need for collective problem solving. Villages and cities have emerged in ‘dissipative flow structures’ in which organization (information processing capacity) spread out from cities into their hinterland, enabing energy and other resources to increasingly flow into cities to meet the needs of the population. Information processing is thus the driver of urbanization, and energy is the constraint. With the Industrial Revolution, the growth of such dissipative flow structures accelerated very rapidly due to the fact that fossil energy became available and lifted the constraint. Hence the urban explosion of the last couple of centuries. In the second part of the paper, some of the potential consequences of this explosion are discussed. First, whether the ever accelerating increase of global urbanization will continue or not, and then what might be the consequences of that acceleration for urban planning and architecture, emphasizing that cities need to become pro-active rather than re-active. They need to start designing for change rather than responding to it. In a final section we discuss some of the risks to urbanization that are posed by the Information and Communication Technology (ICT) Revolution, and conclude with a suggestion how, in developed countries, information technology might reverse the trend to increasing concentration of the population in cities, whereas for the moment, this is not likely to be the case in developing countries.

At the beginning of 2017, the Peruvian territory has witnessed several severe rains which were amplified by El Niño phenomenon, particularly affecting the coast of the country. Under these circumstances, multiple emergency declarations were issued putting the National System of Risk Management of Disasters, reformed in 2011, to the test of the huaycos, the indigenous Quechua word for flash floods landslide, which stroke the Andean country in January 2017. In light of a major event and the encountered difficulties, the Peruvian State adapts and centralizes the answer to the urgency. This article offers a first reading of the management of the national crisis through its effects in Lima and Callao’s metropolitan area as established centres for the emergency operations and the deployment of the humanitarian activities. Including interviews carried out with members of the central government, the fieldwork and the documentation available at the time of the urgency. The aim of this article is the exposition of the components of territorial resilience then concerned in a context of national crisis, questioning, inter alia, the mobilized resources and the context of their use.

A territory is never facing one hazard but a set of interacting hazards. In a same space, floods, heatwaves/cold-waves or earthquakes usually coexist with industrial activities as energy plants, chemical factories or hazardous materials transportation. Thus, the risk management is still focused on single-hazard approaches at the expense of global, more systemic, ones which integrate the multiple hazards and the associated risks’ interactions on a same territory. This paper put forward an integrated model for multi-risks analysis to enhance a general resilience in urban territories.

This contribution deals with resilient cities and explicitly takes an overall perspective. The concept of
resilience is here used to examine both the event-type perturbations, which process in a relatively short time frame, and the anticipation of urban futures and territorial change dynamics, which process in a long term frame. We propose a practical exemplary of dominos effects spatialization diagnosis during flood and electric power failure in Marseille. Then, resilience of cities is linked with territorial development issues, anticipation of possible tensions and unsafe situations that may emerge due to land planning strategy, water shortages management or innovation diffusion.