Analyse hydrologique de la catastrophe du 15 juin 2010 dans la region de Draguignan (VAR, France)

Hydrological analysis of the catastrophic flash flood of 15th June 2010 in the area of Draguignan (Var, France). The 15th of june 2010 an exceptional flash-flood occurred the in the Var region in south east of France. This flood caused 25 casualties and very strong damages in the area of Draguignan. After this event several researchers and engineers teams conducted field surveys in order to gather information on the dynamics of the flood : peak discharge estimates for the main Argens river and all the tributaries touched by the event, and information on the chronology of the flood based on interviews of eyewitnesses. The SCHAPI and the DREAL PACA organised exchanges between the different teams involved in order to ensure a global coherence of discharge estimates, and to examine the question of the possible return period of the flood. This work of comparison revealed that despite the several sources of uncertainty, the discharge estimates proposed by the different teams were relatively close to each other. This work finally led to a complete cartography of peak discharges including almost 40 local estimates. The spatial repartition of peak discharges appears coherent with rainfall accumulations estimated based on radar data. A more detailed hydrological analysis of the flood was then conducted based on the comparison of estimated peak discharges and hydrographs simulated using a simple distributed rainfall-runoff model. This analysis revealed a great disparity of the hydrological answer of the tributaries of the Argens river. The strongest reactions were observed on the Florieye and the Real rivers for which rainfall accumulations exceeded 350 mm in 24 hours. The Aille river also had a strong reaction despite of much more limited rainfall accumulations on this watershed (200 to 250 mm). On the other hand, the Nartuby river showed a very attenuated answer despite of very elevated rainfall accumulations (exceeding 350 mm) : this could be attributed to the presence of large karst formations in this last watershed. Lastly, the discussion on the return periods of the flood enabled to identify the river reaches where a 100-year return period had probably been exceeded.Suite à la crue exceptionnelle qui s’est produite le 15 juin 2010 dans la région de Draguignan (Var), plusieurs équipes de chercheurs et d’ingénieurs sont intervenues sur le terrain afin de documenter et de caractériser cet événement, en proposant notamment des estimations des débits de pointe sur le cours principal de l’Argens ainsi que l’ensemble des affluents touchés. Des informations sur la chronologie des crues ont également été obtenues auprès de témoins oculaires. Un travail de coordination et d’échanges entre ces équipes a été organisé par le SCHAPI et la DREAL PACA, et a permis de confronter et de mettre en cohérence les résultats obtenus, et d’engager une discussion sur les périodes de retour de la crue. Cette comparaison a révélé que malgré les différentes sources possibles d’erreurs d’estimation, les valeurs de débits proposées par les différentes équipes restaient globalement assez proches. Cette première étape a permis de cartographier les débits sur la base d’une quarantaine d’estimations au total. La répartition spatiale obtenue apparaît, de premier abord, cohérente avec l’estimation des cumuls pluviométriques fournie par les lames d’eau radar. L’analyse hydrologique de l’événement a été complétée en comparant les débits estimés à des hydrogrammes simulés à l’aide d’un modèle pluie-débit simple. Ces résultats mettent en évidence une grande disparité des comportements hydrologiques des affluents de l’Argens. La Nartuby se distingue notablement avec une réponse hydrologique très progressive et atténuée ce qui peut être attribué à l’effet du karst très présent sur ce bassin. Enfin, le travail sur les périodes de retour a permis d’identifier les secteurs pour lesquels la crue a dépassé un niveau centennal.Payrastre Olivier Renaud, Gaume Eric, Javelle P., Janet B., Fourmigué P., Lefort Philippe, Martin A., Boudevillain B., Brunet Pascal, Delrieu Guy, Marchi Lorenzo, Aubert Yoann, Dautrey E., Durand L., Lang Michel, Boissier Laurent, Douvinet Johnny, Martin C., Ruinet I. Analyse hydrologique de la catastrophe du 15 juin 2010 dans la region de Draguignan (VAR, France). In: Evénements extrêmes fluviaux et maritimes. Leurs variabilités spatiales et chronologiques dans l'ouest de l’Europe. 34èmes journées de l’hydraulique Paris, 1 et 2 février 2012. 2012

Sensory neuron-specific receptor activation elicits central and peripheral nociceptive effects in rats

The sensory neuron-specific G protein coupled receptors (SNSRs) have been described as a family of receptors whose expression in small diameter sensory neurons in the trigeminal and dorsal root ganglia suggests an implication in nociception. To date, the physiological function(s) of SNSRs remain unknown. Hence, the aim of the present study was to determine the effects of rat SNSR1 activation on nociception in rats. The pharmacological characterization of rat SNSR1 was initially performed in vitro to identify a specific ligand, which could be used subsequently in the rat for physiological testing. Among all ligands tested, γ2-MSH was the most potent at activating rat SNSR1. Structure–activity relationship studies revealed that the active moiety recognized by rat SNSR1 was the C-terminal part of γ2-MSH. The radiolabeled C-terminal part of γ2-MSH, γ2-MSH-6–12, bound with high affinity to membranes derived from rat skin and spinal cord, demonstrating the presence of receptor protein at both the proximal and distal terminals of dorsal root ganglia. To investigate the physiological role of SNSR, specific ligands to rat SNSR1 were tested in behavioral assays of pain sensitivity in rats. Selective rat SNSR1 agonists produced spontaneous pain behavior, enhanced heat and mechanical sensitivity when injected intradermally, and heat hypersensitivity when injected centrally, consistent with the localization of rat SNSR1 protein at central and peripheral sites. Together, these results clearly indicate that the SNSR1 plays a role in nociception and may provide novel therapeutic opportunities for analgesia