Social and Hydrological Responses to Extreme Precipitations: An Interdisciplinary Strategy for Postflood Investigation

International audienceThis paper describes and illustrates a methodology to conduct postflood investigations based on interdisciplinary collaboration between social and physical scientists. The method, designed to explore the link between crisis behavioral response and hydrometeorological dynamics, aims at understanding the spatial and temporal capacities and constraints on human behaviors in fast-evolving hydrometeorological conditions. It builds on methods coming from both geosciences and transportations studies to complement existing post-flood field investigation methodology used by hydrometeorologists. The authors propose an interview framework, structured around a chronological guideline to allow people who experienced the flood firsthand to tell the stories of the circumstances in which their activities were affected during the flash flood. This paper applies the data collection method to the case of the 15 June 2010 flash flood event that killed 26 people in the Draguignan area (Var, France). As a first step, based on the collected narratives, an abductive approach allowed the identification of the possible factors influencing individual responses to flash floods. As a second step, behavioral responses were classified into categories of activities based on the respondents' narratives. Then, aspatial and temporal analysis of the sequences made of the categories of action to contextualize the set of coping responses with respect to local hydrometeorological conditions is proposed. During this event, the respondents mostly follow the pace of change in their local environmental conditions as the flash flood occurs, official flood anticipation being rather limited and based on a large-scale weather watch. Therefore, contextual factors appear as strongly influencing the individual's ability to cope with the event in such a situation

Analyse des courbes de tarage de 7 stations hydrométriques de la DREAL Alsace

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAUEn 2009, la DREAL Alsace a sollicité un appui de l'Unité de Recherche Hydrologie-Hydraulique du Cemagref (Lyon) pour une analyse des courbes de tarage (relations hauteur-débit) de plusieurs de ses stations hydrométriques présentant une importance particulière pour les débits de crue. Ce rapport présente la méthode bayésienne BaRatin appliquée à sept stations, ainsi que les résultats obtenus et des préconisations pour l'amélioration des mesures

Expertise de la station hydrométrique de la Nartuby à Trans

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [Relecteur_IRSTEA]Camenen, B. ; Dramais, G. ; Paquier, A.Suite à la crue violente du 15 juin 2010 ayant détruit la station hydrométrique de la Nartuby à Trans-en-Provence, une expertise hydrométrique a été sollicitée par le SPC MedEst et la DREAL PACA, dans le cadre de la convention SCHAPI/Cemagref. La relation hauteur-débit à la station actuelle est analysée et modélisée. Le site du pont de pierre en aval est proposé pour constituer une station-fille permettant de mieux mesurer les fortes crues, à l'aide par exemple d'un radar combiné hauteur-vitesse. Des recommandations sont données en vue d'une étude hydraulique du site

Feature-refined box particle filtering for autonomous vehicle localisation with OpenStreetMap

Vehicle localisation is an important and challenging task in achieving autonomous driving. This work presents a box particle filter framework for vehicle self-localisation in the presence of sensor and map uncertainties. The proposed feature-refined box particle filter incorporates line features extracted from a multi-layer Light Detection And Ranging (LiDAR) sensor and information from OpenStreetMap to estimate vehicle states. A particle weight balance strategy is incorporated to account for the OpenStreetMap positional inaccuracy, which is assessed by comparing it to a high definition road map. The performance of the proposed framework is evaluated on a LiDAR dataset and compared with box particle filter variants. Experimental results show that the proposed framework achieves respectively 10% and 53% localisation performance improvement with reduced box volumes of 25% and 41%, when compared with the state-of-the-art interval analysis based box regularisation particle filter and the box particle filter

The Cévennes-Vivarais Mediterranean Hydrometeorological Observatory database

International audienceIntense rain events frequently result in devastating flash floods in Mediterranean regions. To improve the understanding and prediction of these phenomena, the Cévennes‐Vivarais Mediterranean Hydrometeorological Observatory (CVMHO) was set up in 2000. The observation strategies deployed include the detailed and long‐lasting (>10 years) observation in the Cévennes‐Vivarais region (France) using both operational observation systems and research instrumentation. The present note describes the procedures implemented by CVMHO to critically analyze and generate hydrometeorological products for research. The related data can be viewed or downloaded via the Système d'Extraction et de Visualisation des Données de l'Observatoire en Ligne (SEVnOL) interface on the CVMHO Web site

Hydrological analysis of a flash flood across a climatic and geologic gradient The September 18, 2007 event in Western Slovenia

International audienceA Mesoscale Convective System in North-Western Slovenia produced up to 350-400 mm in 12 h on 18 September, 2007. The region impacted by the storm shows significant differences in climatic and geologic properties at short distances. Owing to such variability, extreme flooding concentrated over the Selška Sora watershed at Železniki (103.3 km2), outside the area which received the highest precipitation. Hydrometeorological analyses of the storm are based on accurate analysis of C-band weather-radar observations and data from a rain gauge network. Detailed surveys of high-water marks and channel/floodplain geometry, carried out two months after the flood, are used for hydrologic analyses of the Selška Sora flood. These include estimation of peak discharge at 21 sites. Unit peak discharges range from 5 to 7 m3 s−1 km−2 in basins characterised by size up to approximately 25 km2. Higher unit peak discharges (>10 m3 s−1 km−2), estimated in a few smaller basins, are influenced by intense sediment transport. Observed rainfall, estimated peak discharges, and observer notes on timing of peak discharge are used along with a distributed hydrologic model to reconstruct hydrographs at multiple locations. Examination of the rainfall distribution and flood response shows that the extent and the position of the karst terrain provided a major control on flood response in the region impacted by the storm. Use of the distributed hydrological model together with the post-flood survey observations is shown to provide an accurate description of the flood. Water balance and response time characteristics are examined for selected catchments, showing that event runoff coefficient ranged between 17% and 24% for different catchments. The quality of the peak discharge simulation at the 21 surveyed sites is substantially degraded when using spatially-uniform rainfall over the area covering all the surveyed sub-catchments, mainly due to rainfall volume errors introduced by using the spatially uniform value. On the other hand, the influence of rainfall spatial averaging at the scale of the sub-catchments generally has a very limited effect on runoff modelling, showing that rainfall spatial organisation was not able to overcome the catchment dampening effect for this flood

Analyse bayésienne des courbes de tarage et de leurs incertitudes : la méthode BaRatin

International audienceAmong other methods, Bayesian inference recently emerged as a promising framework for establishingstage‑discharge relationships and for rigorously estimating the associated uncertainty. A methodology and some toolshave been developed to analyse stationary rating curves, i.e., assuming that the stage‑discharge relationship is stableover the period under consideration (no rating shifts). The principles of the BaRatin method are presented through itsthree main steps: 1) determination of hydraulic priors, 2) review and validation of streamgaugings, 3) Bayesian inference and simulation of a set of plausible curves. The operational application of the method is made easier through the GUI BaRatinAGE, which is freely distributed along with the BaRatin software and is currently being integrated into the hydrometry software BAREME. The potential of the method is illustrated with an example of application to a gauging station and with the process of appropriation by a hydrometry service. Besides the application to other types of calibration curves, the main development perspective for the BaRatin method is to take into account non‑stationary effects with time‑varying parameters.Parmi d'autres méthodes, l'inférence bayésienne a récemment émergé comme un cadre prometteur pour établir les relations hauteur‑débit et en estimer l'incertitude associée de façon rigoureuse. Une méthodologie et des outils ont été développés pour permettre l'analyse des courbes de tarage stationnaires, c'est‑à‑dire sous hypothèse de stabilité de la relation hauteur‑débit sur la période considérée (pas de détarage). Les principes de la méthode BaRatin sont présentés à travers ses trois principales étapes : 1) détermination des a priori hydrauliques, 2) critique et validation des jaugeages, 3) inférence bayésienne et simulation d'un faisceau de courbes vraisemblables. L'application opérationnelle de la méthode est facilitée grâce à l'interface graphique BaRatinAGE diffusée librement avec le logiciel BaRatin, et en cours d'intégration dans le logiciel d'hydrométrie BAREME. Le potentiel de la méthode est illustré par un exemple d'application à une station hydrométrique et la démarche d'appropriation par un service d'hydrométrie. Outre l'application à d'autres types de courbes d'étalonnage, la principale perspective de développement est la prise en compte d'effets non‑stationnaires à l'aide de paramètres variables dans le temps

Methods of Post Flood Field Investigation: Lessons learned from trial on Selscica Sora River, Slovenia

No abstract availabl