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Une nouvelle méthode a permis de quantifier des Durées Continues d'Habitat Limitant (méthode DCHL) à partir de chroniques d'habitat potentiel, pour la truite fario (Salmo trutta fario, L.). Cette méthode a été appliquée sur deux cours d'eau naturels et sur une station soumise à éclusée. Elle a été validée sur les deux cours d'eau naturels en ce qui concerne l'habitat limitant pour les jeunes truites de l'année (0+). Elle offre un outil pratique d'analyse des périodes d'habitat limitant en régime naturel. En situation d'éclusées, l'interprétation des résultats est différente et nécessite encore un effort important de suivi biologique.

Les approches déterministes existantes décrivant le fonctionnement physique des écosystèmes d'eaux courantes sont a priori adaptées à l'échelle locale. II nous paraît important de développer une démarche visant à synthétiser ce fonctionnement à l'échelle globale du tronçon de rivière, homogène du point de vue géologique et hydrologique. Pour cela, l'utilisation imbriquée d'outils déterministes et d'outils statistiques est nécessaire. Cette démarche suppose de pouvoir définir, pour chaque question biologique, les échelles spatiales et temporelles pertinentes, à l'intérieur desquelles les variables physiques peuvent être décrites par des grandeurs statistiques. Au regard des outils existants dans les différentes disciplines physiques, de ceux qui peuvent être adaptés à cette préoccupation et de ceux qu'il est nécessaire de développer, nous présentons différents axes de recherches possibles, associant hydrologues, géomorphologues, hydrauliciens et hydrobiologistes.

IRIP – Indicator of Intense Pluvial Runoff (French Acronym) – is a method to map the susceptibility of territories to surface runoff generation, transfer and accumulation. The method is based on a geomatic combination of landscape factors extracted from topography, land use and soil type. This study is part of the method evaluation process and suggests using information from post-event surveys of surface runoff events to evaluate the agreement between the IRIP maps and the field observations. Surface runoff susceptibility maps are produced at five meters resolution for three impact areas on railways with different infrastructure and environment configurations. First, information categories are extracted from the post-event surveys, and then the IRIP maps are analyzed to see if and how the information categories are retrieved. This study shows that the IRIP maps fit the impact description. The areas susceptible to surface runoff transfer fit the gullies locations and the areas susceptible to surface runoff accumulation fit the sediment deposit traces. The comparison also highlights that the IRIP maps can give further information on the event spatial dynamics. Given the simplicity and the robustness of the mapping method, IRIP can be a tool to perform surface runoff post-event surveys and to improve the surface runoff hazard assessment.

For sustainable and integrated flood management, small actions in the hillslopes and non-structural measures appear interesting, either to diminish the need for large flood mitigation infrastructures (whether sewerage networks or hydraulic structures in the river – which may have severe impact on the river ecosystems), or as complementary to these structures. However, the effect on flood mitigation of land-use modification and small storage or runoff control facilities is still debated in scientific literature. The effect of various structures spread over the catchment is difficult to assess, and hazardous to generalize from one studied catchment to another, which explains why the debate is still open. This study contributes to identify context features that could also explain constrasting results. Focusing on a West-Mediterranean Northern and Southern countries literature, we compare first traditionnal and modern hillslope actions against runoff in both countries. Then, we search in the physical contexts differences that might explain why actions in the hillslopes are more studied in Europe than in Maghreb. But the priorities of national or regional policies also explain differences in the perception of efficiency: the interest of hillslope actions is different if the aim is to limit erosion and pollutant transfer and/or to mitigate large floods. Pollution and how ecological status is taken into account in flood mitigation project assessment are also crucial points.

Shock ignition of DT capsules involves two major steps. First, the fuel is assembled by means of a low velocity conventional implosion. At stagnation, the central core has a temperature lower than the one needed for ignition. Then a second, strong spherical converging shock, launched from a high intensity laser spike, arrives to the core. This shock crosses the core, rebounds at the target center and increases the central pressure to the ignition conditions. In this work we consider this latter phase by using the Guderley self-similar solution for converging flows. Our model accounts for the fusion reaction energy deposition, thermal and radiation losses thus describing the basic physics of hot spot ignition. The ignition criterion derived from the analytical model is successfully compared with full scale hydrodynamic simulations.