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In the field of natural hazards, there is a strong consensus on the interest of using centennial chronologies of past events. In order to grasp the evolution of natural hazards and of the processes at their origin, it is necessary to contextualize the chronologies resulting from historical sources by taking into account all potential explanatory factors and their interactions. On the basis of a geohistorical and systemic approach, this article provides a lecture grid that operationalizes the contextualization workflow, so as to optimize the chronologies of past events. The spatial and temporal matching between the events and the different components of the territorial system studied leads to a comprehension of all factors at play, and thus, of the hazard and risk evolution. This approach is illustrated with the analysis of a spatial and temporal chronology of avalanche risk in the Vosges Mountains (northeast of France) since the end of the 18th century. Four prisms – avalanche hazard, risk, event and "sources effect" – combine and their respective weights vary in time and space. Climate and land use changes explain the "disappearance" of avalanche triggers at low elevations and of those flowing down from the summits to the valley bottoms. The combined evolutions of stakes, climate and land use contribute to explain the risk evolution. Finally, the "sources effect" preponderantly influences the evolution of the amount of events. Various results regarding the local evolution of the risk and the comprehension of environment-society interactions which have generated the chronology suggest that this approach could be valuable for many applications in geohistory of risks.

In the aftermath of a disaster, the debris caused by the destruction of property or vegetation become a crucial problem. The increase in the volume of debris, the growing requirements for environmental protection, the cost of waste collection and treatment for local authorities or companies are increasingly complex challenges for lands subject to natural, technological or political disasters (conflicts). The landfall of the cat 5 hurricane Irma and, to a lesser extent Jose, generated an amount of debris estimated up to 60 000 metric tons only for the French part of the island of St. Martin, i.e. 1.7 metric ton per capita. The waste collection and treatment represented a huge challenge. The waste collection took four months whereas the full process (treatment and recycling) was still going on in November 2018. Operations have been hampered by the cyclone itself (destruction of infrastructure and material resources, lack of laborers…) and by the constraints of insularity (low volume to value, lack of storage areas...). On the other hand, Saint-Martin benefits from a single public operator (the collectivity of Saint-Martin) and a recycling and landfill site called “Écosite” with rising skills in waste valorization despite modest funds. The example of Saint-Martin shows all the difficulties of post-cyclonic debris management and emphasizes the dependence of the production of debris and their treatment to the characteristics of the island.

INUNDATIONS IN LISBON DURING THE 20TH CENTURY AND THEIR URBANAND PHYSICAL CAUSES. Lisbon often suffers inundations, which must be classified as urban inundations, because the flooded areas involved are impermeable due to urban development. These inundations are not related to the overflow of watercourses, but can be classified as flash inundations because of the speed with which they form and spread. The present study covers a time period from 1918/19 to 1997/98, during which 420 occurrences were recorded in two leading daily newspapers, «O Século» and «Diário de Notícias». The research based on these newspapers takes into account daily rainfalls above 10 l/m2 recorded by the Instituto Geofísico Infante D. Luís, as well as daily rainfall below this level but that have also caused inundations. The analysis of the frequency and evolution of these inundations has showed that they occur more often during the autumn (specially in November) and that from the seventies onwards, they have decreased considerably, while at the same time the total rainfall volume has increased, as well as the maximum hourly rainfall that bring them about. Fieldwork was very important in the definition of flooded sites. Research was carried out to specify the physical factors (relief and drainage basins) and urban network (squares and streets). The relationship between these urban factors and the old drainage network was also taken into account in order to distinguish increasing inundation factors. Apart from the description of the physical characteristics of these sites, they were also typified through factor analysis. A hazard factor was attributed to each site based on inundation frequency. The most endangered areas and sites are located mainly in the «Frente Ribeirinha» (along the river bank) built upon the terminal sectors of the natural watercourses, which consists of the receptor streets and receptor squares of the flow. These streets and squares lie perpendicular to the ancient watercourses, and in places where artificial barriers and micro depressions exist. The latter result from the artificial surface of the riverside embankment. Other critical sites exist throughout the town mainly because of obstruction problems or deficient drainage systems, often aggravated, by newly built up impervious areas.

New Orleans’ post-Katrina disaster recovery is still incomplete. However, settlement adjustments already display a “second-order” adaptation pattern to the persistent hurricane hazard. The “second-order” adaptation concept encompasses the adjustments that result from individual household decision instead of planned action by government’s decision. However, New Orleans is still reluctant to admit the benefits that could result from the shrinkage of its territorial footprint.

The rate of urban development in flood-prone areas in the Paris region continues unabated. The new State orthodoxy in matters of urban planning predominantly rests on reducing the vulnerability of goods and population to flood risks which, as stated by French public authorities, should not systematically be equated to withholding development approvals or freezing risk-exposed territories. The challenge consists in controlling urbanization of the most exposed areas while providing the means for urban and economic development of already urbanized and less exposed areas. The new position taken by the State is leading contracting authorities to reoccupy sparsely urbanized flood-prone districts with the aim of constructing more housing and office buildings. In so doing, the planning strategies and principles at the nexus of environmental approaches to the compact city converge. This article reflects on the design of an urban renewal project “Seine Ardoines” (an industrial district in the town of Vitry-sur-Seine in the Ile-de-France region) and shows how the design process can benefit from the “guide plan”. Implemented as an original planning tool, it enables flood risks to be integrated into the urban regeneration of an industrial site, without calling into question the development strategies promoted by the local authorities.

The La Tolita site appeared on the Pacific coast of northern Ecuador around 3000 BP, and its culture quickly spread throughout the interior alluvial plain of mangrove and thick rainforest vegetation up to an elevation of 2000m along the Andean slopes. New geomorphic evidence shows that the flowering of the La Tolita culture could have followed a natural disaster that opened a new waterway, which facilitated communication with gold bearing areas and Andean communities landward. The La Tolita area is located in the Esmeraldas-Tumaco seismic zone, one of the most active on earth. The channel avulsion is correlated with active fault motion in the alluvial lowlands of the Santiago and Cayapas River basins. We question here the relation between the two following phenomenons, natural disaster and cultural flowering.

The Loire river is much less developed and artificialized than other big French rivers. However, its catchment basin planning has been at the heart of significant controversies for the last decades. The opposition between developers and environmental protectors has been strong but profitable insofar as it has been helping the transition from a technician watercourse management method – which prioritizes watercourse control through important developments regardless of their environmental effects – to an environmental management method – which strives to articulate planning while preserving the natural balances existing in hydrosystems. Studying the Loire catchment basin may thus highlights the rise of a new and more environment conscious watercourse management method.

Since the mid 19th-century, the vulnerability of the economic stakes on this coastal fringe has been managed mainly by controlling the hazards; this control is coordinated by the national government, which has initiated coastal defense practices. At the beginning of the 1980s, natural risk prevention policies favored managing the consequences of natural disasters, with the creation of the CatNat insurance regime to indemnify natural disaster victims. By the middle of the 1990s, new natural risk management strategies had been invented to complete the control of natural hazards. As part of the emerging philosophy of Integrated Coastal Zone Management (ICZM), the French government encouraged the development of natural risk prevention policies by establishing Natural Risk Prevention Plans (PPRn) in 1995. These PPRn were a new approach to shoreline management that favored controlling development in coastal communities. At the beginning of the 21st century, the French government set down the general orientations for managing natural coastal risks, but it was not the only stakeholder involved. Collective action emerged, bringing the national government, public institutions, territorial and local authorities together to develop risk management policies. This collective action was facilitated by a form of decentralization of natural coastal risk management, involving regional or local implementation of the strategic orientations of shoreline management, respecting the general principles defined by the national government. These changes are part of the ICZM implementation process, which has been under way since 2005.

The tsunami that affected the Indian ocean’s rims on December 26, 2004 claimed close to 226 000 lives, mainly on the island of Sumatra, Indonesia, which suffered overwhelming devastation. This article asks whether a tsunami warning system is needed in the Indian Ocean where the probability to experience a similar catastrophe is very scarce. In addition, other alternatives including land use planning and education focused on tsunami risk management are presented. Their application could strongly reduce financial and human losses if such hazard had to occur again.

On the uninhabited atoll of Clipperton, the fourth French Pacific territory, the land and lagoon ecosystems are in drastic degradation while natural hazards are severe. Since the sixties, a desertification process has occurred apparently due to the elimination of pigs introduced by the end of the 19th century, and consequently to the proliferation of millions of omnivorous crabs and thousands of birds. The lack of vegetal cover was already the natural stage before human presence showing therefore a positive human impact on this exceptional environment. Considering these environmental stakes, and enlightened by economic and geopolitical issues of the region, the author proposes, after a limited planning, a land partition between a fully protected area and a human settlement sector which would guarantee French sovereignty on this zone lusted for its resources.

Since the last twenty years, natural hazard have taken an important place in our mind and in the media. Considered in the pastas the manifestation of the divine's anger and of the fatality, scientist progress has brought us to a rationalization of the way of thinking, making us less tolerant with natural hazard. If many studies have been made in a frame of the characterisation of the physical process that bring to natural hazard, few studies have been made in a frame of the a global estimation of the exposition of each country to natural hazard using two approaches of the vulnerability. The aim of our paper is to present a comparative study of the estimation of the risk exposure of each country, combining two approaches of the vulnerability (social and economic) with a probabilistic approach of the hazard. This work highlights the fact that using a social approach of the vulnerability, we can observe a great inequality between "rich" countries and "poor" countries that present a high level of exposure to risk while using an economical approach of the vulnerability, "rich" countries present the highest level of exposure to risk.