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International audience

Les côtes basses sableuses sont des espaces contraints et sensibles aux aléas côtiers. L’implantation des activités humaines à proximité du bord de mer fait de ces espaces des territoires du risque. L’identification des territoires exposés au recul du trait de côte figure parmi les objectifs de la stratégie nationale de gestion intégrée du trait de côte portée par le Ministère de la Transition écologique et solidaire. Pour ce faire, la stratégie nationale s’appuie notamment sur la mise en réseau des observatoires régionaux du trait de côte. Cet article propose une démarche géomatique de spatialisation d’un nouvel indicateur de prédisposition associé au risque érosion, commune à deux de ces observatoires régionaux : le Réseau d’observation du littoral de Normandie et des Hauts-de-France et l’Observatoire régional des risques côtiers en Pays de la Loire. La prédisposition est estimée, par l’agrégation dans des unités d’observation appelées « boites », de trois variables spatialisées : (i) l’évolution historique du trait de côte (ii) la distance entre le trait de côte et les constructions, les routes carrossables et les campings situés dans la bande des 100 m et (iii) la présence/absence d’ouvrages de protection. Le calcul de l’indicateur pour chaque enjeu puis la réalisation d’une synthèse à l’échelle des territoires permet une classification des territoires exposés au risque d’érosion côtière le long de la côte ouest de la Manche et de la côte nord de la Vendée Low sandy coasts are small and constrained spaces very sensitive to coastal hazards. The settlement of human activities next to the coastline sets up at-risk territories. The identification of territories exposed to coastal erosion is one of the objectives of the French national strategy for integrated coastal management initiated by the French Ministry of Ecology. This national strategy relies on the network of regional coastal observatories. This paper proposes a common geomatics approach of two of these regional observatories aimed at spatializing a new coastal erosion risk indicator. The partnership between the "Réseau d’observation du littoral de Normandie et des Hauts-de-France" and the "Observatoire régional des risques côtiers en Pays de la Loire", aims at applying this indicator along the sandy coasts of western Manche and northern Vendée, France. The indicator is composed of the combination of 3 variables into spatial units (“boxes”): (i) the historical shoreline change, (ii) the distance between the shoreline and the buildings, roads and campsites located in the 100-m coastal strip and (iii) the presence/absence of coastal protections. The computation of the indicator for each stake, at the scale of the territories, allows the ranking of the erosion risk territories Las costas bajas arenosas son espacios contraídos y sensibles a los riesgos costeros y la localización de actividades humanas a proximidad del borde de mar hace de estos espacios territorios de riesgo. La identificación de áreas expuestas al retroceso de la línea de costa figura entre los objetivos de la estrategia nacional de gestión integrada de la línea costera desarrollada por el Ministerio de la Transición Ecológica y Solidaridad. Para ello, la estrategia nacional se apoya principalmente en la puesta en marcha de redes de observatorios regionales en la línea de costa. Este articulo propone desde un enfoque geomático de espacialización, un nuevo indicador de exposición asociado al riesgo de erosión en dos observatorios regionales: La Red de Observación del litoral de Normandía y de los Altos-de-Francia y el Observatorio regional de riesgos costeros en el País de la Loira. La exposición es estimada, por la agregación de unidades de observación llamadas «cajas», de tres variables espacializadas : (i) la evolución histórica de la línea de costa (ii) la distancia entre la línea de costa y las construcciones, las rutas transitables y los campings localizados en una franja de 100 metros y (iii) la presencia/ausencia de obras de protección. El cálculo del indicador para cada uno y posteriormente la realización de una síntesis a escala de los territorios, permite una clasificación de las áreas expuestas al riesgo de erosión costera a lo largo de la costa oeste de la Mancha y de la costa norte de la Vandea.

International audience

France is the fifth largest producer worldwide of soft wheat. Every year over 35 million tons of wheat are harvested (average 2011-2017, data from France AgriMer) on the territory. Hence, the cereal sector occupies an important place in the French agricultural economy.However, because of its high dependence on the atmospheric conditions, wheat production is vulnerable to climate change. Since the mid-1990s, a stagnation of yield has already been observed. According to the agronomists, the main cause is climate change. Water deficit during the production and days of scalding during the filling of the grains. By 2050-2100, these extreme events are expected in the most likely scenario (i.e. warmer springs and summers). Hence, it is of importance to know if the shortening of the plant cycle resulted from the rise in the global temperature could prevent these extreme events from happening and if other related impacts could occur.This study illustrates 2 agricultural plains containing open fields in the Normandie area, located in the north-west part of France. In this region, wheat locally occupies more than 50% of the agricultural land. These two areas are the plain of Caen which is under the influence of an oceanic climate and the plain of Evreux where the climate is slightly more continental.The aim of this communication if to present what the climatic conditions for the soft wheat in 2050 and 2100 would be and to compare these projected periods with the ones of the reference period (1976-2005). The reported results were obtained by the means of a simulation of the phenology to which is grafted the occurrence of climatic hazards such as water deficit, thermal exhaustion, frost days, vernalization, low temperatures and radiation deficit. Indeed, those hazards are able to generate consequences to the agricultural yield. The climatic data are extracted from ALADIN-Climate (data from CNRS-2014) in the case of three RCP scenarii of IPSS, available on the website of Drias Les futurs du climat.In the context of pronounced climate change, along with unchanged sowing dates by 2050 and 2100, the increase in temperatures would lead to shorten the crop cycle, and hence to a date shift in the plant phenology. Consequently, there would be a shorter overlap between the end of the crop cycle and the summer period and, usually characterized by heat waves and water stress events which are expected to occur more often. Thus high temperature triggered scalding would not be observed as much as expected and the cumulated water limitation would be also lower. However, because of this precocity, emerging consequences might be expected regarding deleterious effects of lower temperatures during meiosis, and decrease of solar radiation at the onset of stem elongation. Mild winters would also reduce the days of vernalization, limiting cold requirements during tillering. This study demonstrates the use of bioclimatic models to unravel the crop phenology modifications, expected to occur by the end of the century, under the main environmental climatic drivers.

International audience

En Normandie, la culture du blé qui occupe 24 % de la SAU régionale tient une place importante parmi les productions végétales. Le changement climatique peut-il avoir des conséquences sur le cycle de cette céréale et perturber les pratiques et les espaces concernés ? Cet article projette la phénologie et les performances culturales de l’agrosystème céréalier régional d’ici la fin du 21ème siècle. Il s’appuie sur une modélisation bioclimatique qui mobilise les données CNRM-2014 du CNRS et de Météo-France sorties du modèle régional ALADIN-Climat pour trois scénarios RCP du GIEC. Dans le cas de dates de semis inchangées aux horizons 2050 et 2100 et d’un changement climatique prononcé, l’élévation des températures engendrerait un raccourcissement du cycle et donc une anticipation calendaire de la phénologie. Ce qui éviterait un chevauchement de la fin du cycle avec la période estivale à laquelle sont associés des événements de sécheresse et de vagues de chaleur dont la fréquence pourrait augmenter dans les prochaines décennies. En conséquence, l’échaudage thermique et le déficit hydrique seraient moindres que ce que l’on pouvait envisager. Toutefois, cette précocité pourrait perturber des stades plus précoces de développement du blé tendre : basses températures à la méiose et déficit de rayonnement au début de la montaison. De plus, la douceur accrue des hivers pourrait engendrer une diminution du nombre de jours de vernalisation, phase nécessaire pour la floraison des variétés d’hiver. Cette étude démontre l’intérêt des modèles bioclimatiques pour envisager les modifications possibles de la phénologie des cultures attendus d'ici la fin du siècle.

National audience

Africa is a favorable site for meteorites recovery in which the total number of meteorites represents more than 1/6 of all extra-terrestrial rocks recovered from the entire world. This work studies the classification of the African meteorite finds, their masses’ distribution and their alteration grades to verify some factors influencing the weathering processes. The African population comprises an abundance of stony meteorites with high percentages of rare meteorites of the world collection: Martian meteorites (62%), Ureilites (51%), Rumuruti (59%), Lunar (47%), and HED (46%). Furthermore, throughout the last two decades, the authors noted an important increase of achondrite meteorites compared to the Australian and Antarctic collections. The mass distribution of African population shows that most of the recoveries (72%) have masses more than 100 g. It peaks at about 1 kg, compared to about 0.1 kg for the Australian collection and 0.01 kg for the Antarctic finds. On the other hand, the distribution of weathering grades (W) shows the predominant of W1 (32%) and W2 (34%) which proves a better preservation of meteorites. The factors influencing the mechanism and rate of alteration of African finds include the climate, which is the main factor, the mass, the terrestrial age and the initial porosity of the samples.

À l’extrémité nord-ouest du Pays d’Auge, les falaises des Vaches Noires constituent un site côtier long de 4,5 km à la morphologie unique de badlands, évoluant sous l’action combinée de processus subaériens et marins. Des glissements et éboulements de blocs calcaires/crayeux se produisent en partie sommitale. À l’aval, la morphologie chaotique est affectée par des coulées boueuses actives aux dynamiques et aux modalités d’extension diverses. L’escarpement basal (défini comme trait de côte) est battu par les houles. Ce dernier connaît alternativement des phases d’érosion en période de haute marée, puis d’accumulation grâce aux apports de matériaux issus de l’amont du versant côtier. Le fonctionnement non linéaire dans le temps et l’espace de ces falaises sont le résultat de relais et de combinaisons de processus que nous cherchons à définir et quantifier. Afin de déterminer l’évolution morphologique historique des versants, une analyse par emboîtement d’échelles spatiales et temporelles est menée. À l’aide de documents cartographiques anciens, de photographies aériennes de l’IGN, de MNT LIDAR, puis de documents historiques (archives, photographies, etc.), nous estimons des distances et des taux de recul de l’escarpement principal et secondaire, ainsi que l’évolution du trait de côte. L’analyse diachronique de différents documents permet d’estimer les vitesses et rythmes d’évolution des falaises des Vaches Noires sur des pas de temps longs (257 ans) et de les comparer aux vitesses des secteurs côtiers normands marneux avoisinants. Un cycle d’évolution complet des falaises est de 250 à 300 ans est également proposé. At the north-western end of the Pays d'Auge, the cliffs of the Black Cows constitute a 4.5 km long coastal site with a unique morphology of badlands, evolving under the combined action of subaerial and marine processes. Landslides and limestone/chalk rockfalls occur at the upper part of cliffs. At the downstream part, the chaotic morphology is affected by active mudflows with different dynamics and modalities of extension. The basal scarp (defined as a coastline) is beaten by swells. The latter alternates between marine erosion phases (during heavy agitations), followed by accumulation through the input of materials from the upstream coastal slope. The non-linear functioning in time and space of these cliffs is the result of relays and combinations of processes that we are researching to define and quantify. In order to determine the historical morphological evolution of the slopes, an interlocking analysis of spatial and temporal scales is carried out. Using ancient cartographic documents, IGN aerial photographs, MNT LIDAR, then historical documents (archives, photographs, etc.), we estimate distances and retreat rates of the main and secondary scarp, but also the shoreline from the basal scarp. Cross diachronic analysis of the different documents offers a long-view of velocities and rhythms of the whole cliffs (257 years) and to compare them with others Normandy marl coastal areas. A complete cliff evolution cycle of 250 to 300 years is also proposed.

International audience

High-resolution digital elevation models (HRDEMs) on coastal areas, particularly cliffs, are an important asset for analyzing and quantifying the processes affecting their morphology. The Vaches-Noires coastal cliffs, located at the north-western part of the Pays-d’Auge region (Normandy, France), are an ideal site for the study of subaerial and marine erosion processes. Indeed, the coastline evolves through the accumulation of deposits resulting from rotational landslides and/or mudflows at the base of the cliff which are then undermined by the sea. The 3D modeling of a representative sector of the cliffs appears a suitable solution to monitor and quantify this evolution using HRDEMs. This paper presents the whole of a monitoring protocol, with high spatial resolution and high temporal resolution, on an original location characterized by reliefs of Badlands in coastal environments. The first results of these investigations are described with an evaluation of two methods for the creation of 3D models: a “heavy” method by Terrestrial Laser Scanning (TLS) monitoring, and a “light” method using “Structure from Motion” (SfM) terrestrial photogrammetry. The small investment of time in the field and money is an important asset of the SfM method. The textured rendering quality of the SfM model makes it a powerful tool for geomorphological analysis. According to a recurrent monitoring protocol involving both measurements, it was possible to compare the accuracy of the SfM and TLS models. The results show a high accuracy of the SfM models with an overall average error of 0.05 m. The representations of the zones of accumulation and erosion as well as their spatial succession allow to investigate the dynamics of the involved processes with both methods. Preliminary volume calculation results are conclusive for TLS models.

L’hypothèse maîtresse que la capacité d’un territoire à récupérer ses fonctions de base après une catastrophe dépend de son niveau de performance globale déjà présent en période normale à mettre à disposition des ressources (au sens large : services, activités, ravitaillement, communication, etc.). Il s’agit ainsi de modéliser le système de contraintes spatiales, fonctionnelles et de coûts/effort, conditionnant, à différentes échelles d’espace et de temps, la mobilisation des ressources d’un territoire, par sa population et par ses acteurs décideurs, en situation ordinaire et en situation dégradée. Nous présentons ici une première exploration sur la capacité qu’offre le rapprochement « ergonomie spatiale/résilience territoriale » à produire des outils de diagnostic pour aider au développement d’une gestion résiliente. La démarche méthodologique pour analyser et cartographier un degré d’ergonomie spatiale au sein d’un territoire sera présentée à travers un exemple expérimental sur l’agglomération strasbourgeoise. L’ensemble de la démarche a pour but de construire une information de synthèse qui puisse aider à définir un schéma innovant en matière d’organisation et de fonctionnement résilients., The use of spatial ergonomics in the issue of resilience is based on the assumption that the ability of a territory to recover its basic functions after a disaster depends on its overall performance level already present during normal times to make available its resources (in the broadest sense: services, activities, supplies, communication, etc.). It is thus necessary to model the system of spatial, functional and cost constraints, conditioning, at different spatial and temporal scales, access to the resources of a territory, by its population and its decision-makers (institutions, Companies), in ordinary situations and in a degraded situation. We present here a first exploration on the capacity of the relation "spatial ergonomics / territorial resilience" to produce diagnostic tools to help develop a resilient management. The methodological approach to analyzing and mapping a degree of spatial ergonomics within a territory will be presented through an experimental example on the Strasbourg agglomeration. The aim of the whole approach is to construct renewed and synthetical information useful to design organization and functioning schemes of resilience.

International audience; Severals aerial and geophysical methods were carried out on "les Vaches Noires" cliffs (Normandy, France). This particular geological site is typical of Badlands formation, exhibiting Cretaceous to Jurassic formations. These cliffs are submitted to strong erosion processes previously described by numerous works. A new study was undertaken to best-understand the phenomenae, combining an aerial observation with a geophysical imaging. In that purpose, a Digital Terrain Elevation were constructed by means of photogrammetric method applied to hundreds of images collected by drone survey. Complementary 3D thermal infrared model was also considered to assess surface materials characteristics and subsurface hydrology. The Electrical Resistivity Imagery were implemented according to both transverse and parallel profiles to the coastal line, (i) from the top to the bottom of the cliffs, (ii) as well as at the bottom of the cliffs and onto the beach. A recent 3D-inverse electrical method were applied to take into account the whole topography and the layers direction of the geological formations. Spontaneaous Potential also locally provides enriched information on hydrological pathways. Finally a local geophysical model were obtained offering a more comprehensive interpretation of cliffs erosion processes.

International audience

The study of meteorites provides insight into the earliest history of our solar system. From 1800, about the year meteorites were first recognized as objects falling from the sky, until December 2014, 158 observed meteorite falls were recorded in Africa. Their collected mass ranges from 1.4 g to 175 kg with the 1–10 kg cases predominant. The average rate of African falls is low with only one fall recovery per 1.35-year time interval (or 0.023 per year per million km 2 ). This African collection is dominated by ordinary chondrites (78%) just like in the worldwide falls. The seventeen achondrites include three Martian meteorite falls (Nakhla of Egypt, Tissint of Morocco and Zagami of Nigeria). Observed Iron meteorite falls are relatively rare and represent only 5%. The falls' rate in Africa is variable in time and in space. The number of falls continues to grow since 1860, 80% of which were recovered during the period between 1910 and 2014. Most of these documented meteorite falls have been recovered from North-Western Africa, Eastern Africa and Southern Africa. They are concentrated in countries which have a large surface area and a large population with a uniform distribution. Other factors are also favorable for observing and collecting meteorite falls across the African territory, such as: a genuine meteorite education, a semi-arid to arid climate (clear sky throughout the year most of the time), croplands or sparse grasslands and possible access to the fall location with a low percentage of forest cover and dense road network.

(IF 3.07 [2018]; Q1); International audience; In risk analyses, two components are taken into account: (1) hazard analysis, including susceptibility and temporal occurrence, and (2) consequence analysis, including characterization of elements at risk (EaRs) and their vulnerability. This study focused on characterization of EaRs, in which items are spatially displayed and impacted by natural events. Several methods can assess these EaRs through expert or engineering approaches. Among the expert approaches, the multicriteria method is more flexible and allows integration of a wide range of information in order to characterize and discretize different EaRs. Traditionally, the mapping and criteria accuracy of EaRs is the same at all spatial analysis scales, while the hazard accuracy changes according to the spatial scales. Therefore, we propose an approach based on the selection of different information/criteria among several private or open access multiple geographical databases to adapt the mapping and criteria accuracy of each EaR according to the hazard analysis spatial scale. After harmonizing the different databases and merging them under GIS, a single database per work scale is created through a specific procedure with interoperability of results between scales. Thus, the number of criteria used to describe these EaRs will depend on the scale of work and the spatial scale of the analysis. To develop and test the transposability of this method, three experimental coastal study sites subject to several hazards (multirisk) have been selected in Normandy (France) with error estimations ranging between 10% and 20%. Subsequently, these data can be integrated into risk and multirisk analyses.

International audience

Despite many efforts to improve road safety, the road accident statistics remain a concern throughout the world. This work, after considering for France in particular the possible reasons for this, proposes to extend the issue of Road Safety to the land planning problematic which responds to the characteristics of a spatialized complex system. The methodology used in the ANR program CRITERE mixes interdisciplinary and multi-stakeholder purpose. It combines representations structured by explicit data models, and the more empirical concepts expressed by experts in charge of local public action. The tool provides a user-friendly mapping formulation of partners' opinions and conclusions, highlighting the possible correlations between forms and characteristics of the area, road safety measures, accident and infrastructure observed. It gives the possibility to identify, spatialize, qualify and compare areas for treatment. This application is placed in the perspective of hoisting the issue of road safety among the strategic concerns of territorial management.

Le pic d’accident piéton chez l’enfant se situe en France, comme dans beaucoup de pays industrialisés entre 11 et 13 ans, à l’entrée dans l’enseignement secondaire. Les raisons pour lesquelles cette vulnérabilité augmente alors que les compétences impliquées devraient s’être améliorées ne sont pas claires. En articulant deux champs d’analyse de la sécurité routière (l’accidentologie fine et spatialisée avec l'analyse approfondie des comportements et des facteurs psychosociaux), notre projet a eu pour objectif de cerner finement la mobilité des collégiens et l’accidentologie en tant que piéton et de spécifier des déterminants géographiques, psychologiques et sociologiques de ces deux variables et de leurs relations.Une étude de l’accidentologie 2002-2011 des collégiens sur la France entière à partir d’un échantillon de procès-verbaux d’accidents a été complétée, sur le terrain d’étude de la région de Lille (France) par l’analyse spatialisée de l’accidentologie locale (avec scénarios types d’accidents) et de la mobilité des 10-15 ans à partir des données de l’Enquête Ménages Déplacements de 2006.Sur le même terrain d’étude, deux enquêtes ont ensuite été menées. Une première enquête par questionnaire auprès 2500 collégiens de 10 à 16 ans a permis de cerner les pratiques fines de mobilité et leurs déterminants socio-spatiaux. Elle a également permis d’explorer les variables sociodémographiques (âge, sexe) et psychologiques (rôles de sexe, perceptions des normes sociales, des risques, des règles, du niveau de supervision) expliquant les comportements déclarés en tant que piéton. Une deuxième enquête auprès de 300 collégiens a porté sur la perception par les collégiens des environnements de marche connus et inconnus. Elle a permis de dresser une cartographie sensible de leur environnement de marche réel et de procéder à une analyse qualitative des éléments qu’ils utilisent pour juger de l’agrément, du confort et de la sécurité et caractériser leur représentation des trajets positifs ou négatifs en tant que piéton. Cette analyse des caractéristiques de la mobilité et de ses présupposés doit nous permettre d’identifier des facteurs de risque jusque-là non révélés. Une meilleure compréhension des phénomènes et processus en jeu est nécessaire afin de pouvoir déterminer quelles mesures sont à prendre pour pallier ce problème. Cela constitue l’objectif principal du projet que nous proposons.Les résultats obtenus permettent de mieux comprendre les phénomènes et processus en jeu dans l’accidentologie des adolescents de 10-15 ans et de déterminer les mesures à prendre pour pallier ce problème.

The government has identified road safety as an issue of vital importance, and recent research programs, such as those that have been launched by the PREDIT Task Group in France or those supported by the ANR (French National Research Agency), seek to develop "new knowledge for safety". Their objective is to take into account the sociotechnical system composed of "risks associated with transportation” on a larger scale. Given this context, it is necessary to go beyond the specific analysis of black dots and run a broader geographical analysis of traffic accidents, in connection with the development of the city. The objective here is to identify a combination of factors that produce dangerous situations and, in particular, to seek the structural causes of these accidents (infrastructure, urban environments, the distribution of functional areas that control the flow, etc.). The research presented here aims specifically to analyze traffic accidents linked to the characteristics of the daily mobility of people across the Urban Community of Lille (LMCU). Household Commute Surveys (EMD) conducted within local authorities provide valuable information on the mobility of people, but the accurate mapping of mobility alongside traffic accidents is hard to achieve. The approach seeks, first and foremost, to describe and map the areas of mobility in order to highlight the areas supporting many flows, and those that send or receive those flows, in accordance with the means and reasons for travel so as to examine the resulting accidents. Secondly, modeling flows on road networks must include the characteristics of the patterns of activity/travel of the households involved. Enquiries on accidents meeting various criteria can then be carried out within the qualified networks.

Despite many efforts to prevent traffic accidents, road accident statistics remain a cause of concern throughout the world. After analyzing the possible reasons for this in France, this study seeks to extend the issue of Road Safety to that of a global territorial issue which responds to the characteristics of a complex spatialized system. The methodology used in the ANR CRITERION program merges both interdisciplinary and multi-stakeholder objectives based on an information system that combines approaches formalized by scientists and experts in the field. This methodology combines them by comparing the representations structured around explicit data models and the more empirical concepts expressed by technical experts in charge of local public action. The tool provides a user-friendly mapping formulation of the opinions and conclusions of the partners highlighting the possible correlations between forms and characteristics of the area, road safety measures, accidents and the infrastructure observed in the field. It makes it possible to identify, spatialize, qualify and compare the areas to be processed. This application seeks to elevate the road safety issue and place it among the strategic concerns of territorial management, beyond its current and still minor involvement in urban development plans.

Background The road crash peak among children is around 11–12 years-old in France, as in many industrialised countries, at the time of entry in secondary school. The reasons why this vulnerability increases while the skills involved should have improved are not clear. By linking two fields of analysis of road safety (fine spatial analysis of crashes and depth analysis of behaviours and psychosocial factors), our project aimed to finely identify the mobility and pedestrian accident involvement of the 10–15 years old and specify geographical, psychological and sociological determinants of both variables. Methods and results A study of accident processes among pedestrians aged 10–15 years over France for the period 2002–2011 was conducted, based on the national accident file and on a sample of accident police reports. It was completed in the field of study of the Lille region (France) by the spatial analysis of local accident data (including the identification of accident scenarios) and the mobility of 10–15 years, using data from the 2006 household travel survey. Two field surveys were then conducted. A first survey among 2500 junior high school students has identified the fine mobility practices and their socio-spatial determinants. It also explored the demographic and psychological variables (age, gender roles, perceptions of social norms, risks, rules, level of supervision) explaining the reported pedestrian risky behaviours. A second survey among 300 junior high school students focused on their perceptions of known and unknown walking environments. It enabled to draw up a sensible mapping of their actual walking environment and a qualitative analysis of the elements using to judge the pleasantness and safety and characterise their representations of positive or negative actual and virtual travels as pedestrian. Conclusions The results allow a better understanding of the phenomena and processes involved in the accident of pedestrian adolescents and to identify measures needed to overcome this problem.

L'objectif de cette recherche est d'interroger le rapport entre le niveau de l'insécurité routière et la disparité sociale. La disparité est appréhendée par sa dimension territoriale, c'est-à-dire par l'appartenance à un espace socialement marqué. La recherche a porté sur le territoire de la Communauté Urbaine de Lille (LMCU). Le choix des quartiers a été fait en sélectionnant 5 zones urbaines sensibles. Ces terrains d'études ont des caractéristiques différentes : taille, centre-ville / périphérie, habitat ancien / grands ensembles... Ces zones sont comparées à des zones de contrôle contiguës mais dont la population présente des caractéristiques socioéconomiques plus favorisées. Un système coopératif d'analyse géographique a été développé, en partenariat avec la LMCU permettant de spatialiser les données issues de recensements nationaux et locaux. L'accès aux procès-verbaux d'accident du département du Nord permet l'analyse des accidents. Ceux impliquant les habitants des zones étudiées ont été sélectionnés, puis spatialisés et codés. La comparaison établie entre Zus et zones de contrôle permet de conclure à un risque relatif ajusté de 1,363. Les analyses sont prolongées par des comparaisons de modes de transports impliqués, les caractéristiques socioéconomiques des habitants et les professions. Social Inequality and Driving Risks. Contribution of a Geographical Approach. The objective of this research is to study the relationship between social disparities and levels of road safety. This disparity is viewed through its geographical dimension, i.e. belonging to a particular space. The research covered the territory of the Lille Urban Community (LMCU). The choice of neighbourhoods was made by selecting 5 sensitive urban areas. These study fields have different characteristics: size, city centre/periphery, old housing/housing estates, etc. These areas are compared with contiguous control areas whose populations have more privileged socioeconomic characteristics. A geographical analysis system was developed in a partnership with LMCU services to spatialize data from national and local censuses. Access to police reports from the Nord department makes it possible to analyse the accidents. Those involving the inhabitants of the study areas were selected and then spatialized and encoded. The comparison established between the sensitive urban areas and the control areas enables us to conclude that there is an adjusted relative risk of 1.363. The analyses are expanded by comparing the methods of transportation involved, the socioeconomic characteristics of the inhabitants and their professions.. Dossier thématique : Economie de la sécurité routière : définition, connaissance et enjeux.

International audience

The peak pedestrian accident in children is in France, as in many industrialized countries between 11 and 13 years for entry into secondary education. The reasons why this vulnerability increases while the skills involved should have improved are not clear. By linking two fields of analysis of road safety (the accident with fine spatial depth analysis of behaviors and psychosocial factors), our project aimed to finely identify the mobility of schoolchildren and accident as a pedestrian and specify geographical, psychological and sociological determinants of these two variables and their relationships. A first study of accidents on the period 2002-2011 of college students on the whole of France from a sample of accident records has been completed, on the field study of the region of Lille (France), through spatialized analysis of local accidents (with typical scenarios of accidents) and analysis of the mobility of 10-15 year olds, using data from the 2006 Household Mobility Survey. On the same field of study, two surveys were then conducted. A first questionnaire survey of 2500 schoolchildren aged 10 to 16 has identified the fine mobility practices and their socio-spatial determinants. It also explored the sociodemographic (age, gender) and psychological (gender roles, perceptions of social norms, risks, rules, Level of Supervision) variables explaining the reported behavior as pedestrians. A second survey of 300 college students focused on the perception by college students of known and unknown walking environments. It helped to draw up a sensible mapping of their actual walking environment and a qualitative analysis of the elements they use to judge the pleasure, comfort and safety and characterize their representation positive or negative journeys as pedestrian. This analysis of the characteristics of mobility and its determinants should enable us to identify risk factors hitherto unrevealed. A better understanding of the phenomena and processes involved is necessary in order to determine what measures are needed to overcome this problem. This is the main objective of the project that we offer. The results provide insight into the phenomena and processes involved in the accident among teenagers of 10-15 years and to determine the measures to be taken to overcome this problem.; Le pic d'accident piéton chez l'enfant se situe en France, comme dans beaucoup de pays industrialisés entre 11 et 13 ans, à l'entrée dans l'enseignement secondaire. Les raisons pour lesquelles cette vulnérabilité augmente alors que les compétences impliquées devraient s'être améliorées ne sont pas claires. En articulant deux champs d'analyse de la sécurité routière (l'accidentologie fine et spatialisée avec l'analyse approfondie des comportements et des facteurs psychosociaux), notre projet a eu pour objectif de cerner finement la mobilité des collégiens et l'accidentologie en tant que piéton et de spécifier des déterminants géographiques, psychologiques et sociologiques de ces deux variables et de leurs relations. Une étude de l'accidentologie 2002-2011 des collégiens sur la France entière à partir d'un échantillon de procès-verbaux d'accidents a été complétée, sur le terrain d'étude de la région de Lille (France) par l'analyse spatialisée de l'accidentologie locale (avec scénarios types d'accidents) et de la mobilité des 10-15 ans à partir des données de l'Enquête Ménages Déplacements de 2006. Sur le même terrain d'étude, deux enquêtes ont ensuite été menées. Une première enquête par questionnaire auprès 2500 collégiens de 10 à 16 ans a permis de cerner les pratiques fines de mobilité et leurs déterminants socio-spatiaux. Elle a également permis d'explorer les variables sociodémographiques (âge, sexe) et psychologiques (rôles de sexe, perceptions des normes sociales, des risques, des règles, du niveau de supervision) expliquant les comportements déclarés en tant que piéton. Une deuxième enquête auprès de 300 collégiens a porté sur la perception par les collégiens des environnements de marche connus et inconnus. Elle a permis de dresser une cartographie sensible de leur environnement de marche réel et de procéder à une analyse qualitative des éléments qu'ils utilisent pour juger de l'agrément, du confort et de la sécurité et caractériser leur représentation des trajets positifs ou négatifs en tant que piéton. Cette analyse des caractéristiques de la mobilité et de ses présupposés doit nous permettre d'identifier des facteurs de risque jusque-là non révélés. Une meilleure compréhension des phénomènes et processus en jeu est nécessaire afin de pouvoir déterminer quelles mesures sont à prendre pour pallier ce problème. Cela constitue l'objectif principal du projet que nous proposons. Les résultats obtenus permettent de mieux comprendre les phénomènes et processus en jeu dans l'accidentologie des adolescents de 10-15 ans et de déterminer les mesures à prendre pour pallier ce problème.

International audience

International audience; A four-year diachronic study was carried out on coastal badlands cliffs ("les falaises des Vaches Noires", Normandy, France) to assess erosion and acretion volumes. Cretaceous to Jurassic facies at cliffs face are exposed to erosion activated by rainfalls on the tableland and tempests and high tidals at the bottom. Consequences have a direct impact both (i) on housing and civil engineering structures and (ii) on Le Havre harbor and the Seine river waterways. More than ten aerial drone surveys were carried out between 2016 and 2019. Recorded images by drone led to accurate Digital Elevation Model (DEM) models by means of photogrammetry. Each DEM georeferenced with differential global positionning system (DGPS) were then compared with each other. Near surface geophysical methods were also performed to understand materials and their properties involved in such processes . Cliff edge retreat can be assessed, while eroded and accumulated volumes are locally calculated. With help of geological study and mainly Electrical Resistivity Imagery, costline retreat and deposits evolution can be explained and evaluated. This study performed at hectometer scale finally allows a wider interpretation of erosion processes at the regional costline scale. The Vaches Noires cliffs are listed Natural zone of ecological interest, fauna and flora belongs to the 26 studied sites of the National Observation Service DYNALIT, labeled by INSU (National Institute of Sciences of the Universe). The presented outcomes stem from the Normandy regional project TéléDeTaC (Télédétection par Drone du Trait de Côte).

International audience; In Normandy, climate change is expected to drastically impact the crop cycle of soft wheat (Triticum aestivum) which ranks in the main cultivated crops in this area (with 24% of the Utilised Agricultural Land). This study proposes to project cereal phenology and performances by the end of the 21st century based on the CNRM-2014 data extracted from ALADIN-Climat (regional model) for three RCPs. In the context of pronounced climate change, along with unchanged sowing dates by 2050 and 2100, the increase in temperatures would lead to shorten the crop cycle, and hence to a date shift in the plant phenology. Consequently, there would be a shorter overlap between the end of the crop cycle and the summer period and, usually characterized by heat waves and water stress events which are expected to occur more often. Thus high temperature triggered scalding would not be observed as much as expected and the cumulated water limitation would be also lower. However, because of this precocity, emerging consequences might be expected regarding deleterious effects of lower temperatures during meiosis, and decrease of solar radiation at the onset of stem elongation. Mild winters would also reduce the days of vernalization, limiting cold requirements during tillering. This study demonstrates the use of bioclimatic models to unravel the crop phenology modifications, expected to occur by the end of the century, under the main environmental climatic drivers.; En Normandie, la culture du blé qui occupe 24 % de la SAU régionale tient une place importante parmi les productions végétales. Le changement climatique peut-il avoir des conséquences sur le cycle de cette céréale et perturber les pratiques et les espaces concernés ? Cet article projette la phénologie et les performances culturales de l’agrosystème céréalier régional d’ici la fin du 21ème siècle. Il s’appuie sur une modélisation bioclimatique qui mobilise les données CNRM-2014 du CNRS et de Météo-France sorties du modèle régional ALADIN-Climat pour trois scénarios RCP du GIEC. Dans le cas de dates de semis inchangées aux horizons 2050 et 2100 et d’un changement climatique prononcé, l’élévation des températures engendrerait un raccourcissement du cycle et donc une anticipation calendaire de la phénologie. Ce qui éviterait un chevauchement de la fin du cycle avec la période estivale à laquelle sont associés des événements de sécheresse et de vagues de chaleur dont la fréquence pourrait augmenter dans les prochaines décennies. En conséquence, l’échaudage thermique et le déficit hydrique seraient moindres que ce que l’on pouvait envisager. Toutefois, cette précocité pourrait perturber des stades plus précoces de développement du blé tendre : basses températures à la méiose et déficit de rayonnement au début de la montaison. De plus, la douceur accrue des hivers pourrait engendrer une diminution du nombre de jours de vernalisation, phase nécessaire pour la floraison des variétés d’hiver. Cette étude démontre l’intérêt des modèles bioclimatiques pour envisager les modifications possibles de la phénologie des cultures attendus d'ici la fin du siècle.

International audience; Coastal environment with high interaction between nature and societies (land-sea interface) are subject to multi-hazards interaction such as landslides, flood or cliff retreat. These territories are characterized by numerous Element at Risk (EaR) located in valley bottoms, front sea, at the outlets of small dry-watershed or on landslide areas. The aim is to quantify the potential consequences of EaR by integrating multiple hazards interaction at various scale analyses. The experimental study site is located in the margin of the Parisian Basin. It is characterized by alternating sequences of plateaus and valleys between Houlgate and Honfleur (Normandy—France). To identify and quantify these EaR, three scales analyses have been used from medium scale (1:50,000 – 1:25,000), to local scale (1:10,000 – 1:2,000) by using multi-criteria approach. To quantify the EaR, we adopted three steps approach: 1) Definition of an initial index value of EaR according to the rank order weighting without considering the hazards (proximity, location, etc.). This initial value is attributed at three different scales. (a) At medium scale, a global value of EaR is defined by integrating all components of the study site (such as built-up areas, agricultural areas, etc.). (b) At medium scale, the infrastructure value (buildings, roads and lifelines) is defined from physical injuries and both functional and structural components. (c) At local scale, the index value is defined according to the variations of intrinsic structural component of building. 2) Considering environment constraint (hazard location) to define a second index value to EaR. It means that we consider the location of EaR in relation to flood, landslide area or both areas. This new value is computed to the initial index value (step 1) to take into consideration these different hazards. Consequently, it is necessary to firstly define boundaries of the hazard (flood envelope, landslide limits) by GIS-approach. These boundaries are defined according to multiple criteria such as distance to the river, low-lying areas or morphology (alluvial plain) for flood area. Potential landslide areas are defined according to parameters as slope degree, curvature, aspect and historical density of landslides. Multi-hazards areas are the conjunction of both flood and landslide areas (including cliff retreat). 3) The initial value of EaRs is combined with hazards and multi-hazards index value by fuzzy logic system. A series of conditions defined by different operators (such as Max, Min, And, Or, etc.) take into consideration the evolution initial value (step 1) of EaR according to the type of hazard (step 2). Two main results emerged from this study. In first, we have quantified potential consequences at three different spatial scale analyses (from medium to local scale analysis) without considering hazards. This provides a first information of sensitive EaRs on the territory even in case of alteration of hazard areas (climate change). However, this first information should be completed with multi-hazards integration in order to highlighted potential consequences to different hazards. Consequently, this multiple scale analysis by integrating consequences to multiple hazard provide a better assessment of EaRs for the purpose of improve the disaster risk reduction.