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il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION; La disponibilité en eau en sous-bois un paramètre important dans la réussite de la régénération. Les scénarios de réchauffements climatiques prévoient une augmentation des épisodes de sécheresse en Europe. Dans ce contexte, le modèle RReShar (Regeneration and Resource Sharing) a été développé. Ce dernier est un modèle de régénération forestière et de partage des ressources. Il réalisait jusqu’à maintenant un bilan en eau succinct afin de pouvoir simulé la compétition des arbres adultes, de la régénération et de la végétation de sous-bois pour l’eau. L’objectif de ce stage a été de concevoir un modèle de bilan hydrique à partir de la littérature, de l’implémenter et de tester son fonctionnement. L’interception de la pluie, simulée à l’aide du modèle de Merriam, simule les interceptions en fonction du taux de recouvrement de façon cohérente. Toutefois, les interceptions s’étendent sur l’ensemble de la parcelle. L’évapotranspiration réelle est calculée à l’aide de la méthode de Turc. Le sol comporte sept réservoirs. L’un des points à améliorer est de restituer la verticalité du processus d’interception. Il serait intéressant de confronter le modèle conçu a des données de terrain afin de pouvoir juger de l’importance des erreurs produites et d’identifier les processus à améliorer.

/ Les travaux sur le recouvrement des coûts présentés dans ce rapport ont été réalisés dans le cadre de la Convention de partenariat 2009 entre le Cemagref et l'ONEMA (thème « instruments et évaluation économique »). Il s'agit ici de tester deux méthodes économétriques différentes permettant de caractériser la situation de recouvrement des coûts pour une population de services d'eau, issues des données 2007 du Système d'Information des Services d'Eau et d'Assainissement (SISPEA). L'apport du présent travail est avant tout méthodologique et ne permet pas d'interprétation des résultats chiffrés en tant que tels.

Purpose: The life cycle impact assessment (LCIA) guidance flagship project of the United Nations Environment Programme (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative aims at providing global guidance and building scientific consensus on environmental LCIA indicators. This paper presents the progress made since 2013, preliminary results obtained for each impact category and the description of a rice life cycle assessment (LCA) case study designed to test and compare LCIA indicators. Methods: The effort has been focused in a first stage on impacts of global warming, fine particulate matter emissions, water use and land use, plus cross-cutting issues and LCA-based footprints. The paper reports the process and progress and specific results obtained in the different task forces (TFs). Additionally, a rice LCA case study common to all TF has been developed. Three distinctly different scenarios of producing and cooking rice have been defined and underlined with life cycle inventory data. These LCAs help testing impact category indicators which are being developed and/or selected in the harmonisation process. The rice LCA case study further helps to ensure the practicality of the finally recommended impact category indicators. Results and discussion: The global warming TF concludes that analysts should explore the sensitivity of LCA results to metrics other than GWP. The particulate matter TF attained initial guidance of how to include health effects from PM2.5 exposures consistently into LCIA. The biodiversity impacts of land use TF suggests to consider complementary metrics besides species richness for assessing biodiversity loss. The water use TF is evaluating two stress-based metrics, AWaRe and an alternative indicator by a stakeholder consultation. The cross-cutting issues TF agreed upon maintaining disability-adjusted life years (DALY) as endpoint unit for the safeguard subject 'human health'. The footprint TF defined main attributes that should characterise all footprint indicators. 'Rice cultivation' and 'cooking' stages of the rice LCA case study contribute most to the environmental impacts assessed. Conclusions: The results of the TF will be documented in white papers and some published in scientific journals. These white papers represent the input for the Pellston workshop', taking place in Valencia, Spain, from 24 to 29 January 2016, where best practice, harmonised LCIA indicators and an update on the general LCIA framework will be discussed and agreed on. With the diversity in results and the multi-tier supply chains, the rice LCA case study is well suited to test candidate recommended indicators and to ensure their applicability in common LCA case studies.

The availability of resources in the understory is essential for the successful regeneration of the forest. However, upon the creation of a gap, an opportunistic vegetation competes with trees seedlings, for light and water mainly. Moreover, climate change subjoins an additional challenge to forest management. A forest dynamics model incorporating resource sharing (RReShar, Regeneration and Resource Sharing) has been developed in order to test the effectiveness on regeneration success of different management methods on regeneration success, over a period of 20 to 50 years and under different climatic scenarios. It implements a large number of processes. RReShar was assessed in this study, paying attention to the consistency and accuracy of the simulations. The development of different vegetation layers and their impact on the resources available were simulated and evaluated through the comparison with experimental data. The influence of the sizes of scenes and number of cells and of vegetation were tested. Simulations by RReShar are consistent in many ways. The absence of constraint on the response curve of the density of the interfering vegetations to the transmitted irradiance by the above canopy causes errors at low light levels. Despite simplicity of tree crowns, it gives acceptable estimates of the intercepted light though probably improvable. Thus the difference between experimental and simulated values is mainly caused by the lack of definition of a buffer zone at the edge of the scene. The decreasing exponential seedling mortality could also be adjusted according to the age of their mother-tree. Avenues for improving the RReShar model are proposed, such as the optimization of computational time, as a function of the number of cells per scene. / La disponibilité des ressources en sous-bois est indispensable pour la réussite de la régénération de la forêt. Toutefois, à la création d'une trouée, une végétation opportuniste entre en compétition avec les semis des arbres principalement pour la lumière et l'eau. De plus, le changement climatique apporte une difficulté supplémentaire à la gestion forestière. Un modèle de dynamique forestière intégrant le partage des ressources (RReShar, Regeneration and Resource Sharing) a donc été développé afin de pouvoir tester l'efficacité, sur 20 à 50 ans, de différents modes de gestion, sous différentes hypothèses de climat, sur la réussite de la régénération. Un nombre important de processus a été implémenté dans RReShar. Il a été éprouvé lors de cette étude, notamment en termes de cohérence et de précision des simulations. Le développement des différentes strates de végétation et leur impact sur les ressources disponibles ont été simulés et évalués par comparaison à des données mesurées. Des tests ont été effectués au niveau de l'influence des dimensions des scènes et du nombre de cellules et de végétaux présents. Les simulations réalisées par RReShar sont cohérentes sur de nombreux points. Une absence de bornage des courbes de taux de recouvrement des végétations interférentes causent des erreurs aux faibles niveaux d'éclairement. Malgré la simplicité des houppiers des arbres, il donne des résultats d'interception de la lumière acceptables mais sans doute améliorables. Ainsi, la divergence entre valeurs réelles et simulées est principalement causée par l'absence de définition d'une zone tampon par rapport au bord de la scène. Il semblerait que la mortalité exponentielle décroissante des semis serait à moduler en fonction de leur âge de leur arbre-mère. Des pistes d'amélioration du modèle RReShar sont proposés, tels que l'optimisation des temps de calcul, en fonction du nombre de cellules par scène.

Pesticides are applied to agricultural fields to optimise crop yield and their global use is substantial. Their consideration in life cycle assessment (LCA) is affected by important inconsistencies between the emission inventory and impact assessment phases of LCA. A clear definition of the delineation between the product system model (life cycle inventory-LCI, technosphere) and the natural environment (life cycle impact assessment-LCIA, ecosphere) is missing and could be established via consensus building. A workshop held in 2013 in Glasgow, UK, had the goal of establishing consensus and creating clear guidelines in the following topics: (1) boundary between emission inventory and impact characterisation model, (2) spatial dimensions and the time periods assumed for the application of substances to open agricultural fields or in greenhouses and (3) emissions to the natural environment and their potential impacts. More than 30 specialists in agrifood LCI, LCIA, risk assessment and ecotoxicology, representing industry, government and academia from 15 countries and four continents, met to discuss and reach consensus. The resulting guidelines target LCA practitioners, data (base) and characterisation method developers, and decision makers. The focus was on defining a clear interface between LCI and LCIA, capable of supporting any goal and scope requirements while avoiding double counting or exclusion of important emission flows/impacts. Consensus was reached accordingly on distinct sets of recommendations for LCI and LCIA, respectively, recommending, for example, that buffer zones should be considered as part of the crop production system and the change in yield be considered. While the spatial dimensions of the field were not fixed, the temporal boundary between dynamic LCI fate modelling and steady-state LCIA fate modelling needs to be defined. For pesticide application, the inventory should report pesticide identification, crop, mass applied per active ingredient, application method or formulation type, presence of buffer zones, location/country, application time before harvest and crop growth stage during application, adherence with Good Agricultural Practice, and whether the field is considered part of the technosphere or the ecosphere. Additionally, emission fractions to environmental media on-field and off-field should be reported. For LCIA, the directly concerned impact categories and a list of relevant fate and exposure processes were identified. Next steps were identified: (1) establishing default emission fractions to environmental media for integration into LCI databases and (2) interaction among impact model developers to extend current methods with new elements/processes mentioned in the recommendations.

The Blasius problem f′′′ + ff′′ = 0, f(0) = âˆ'a, f′(0) = b, f′(+\infty)=\lambda is investigated, in particular in the difficult and scarcely studied case b < 0 \leq \lambda. The shape and the number of solutions are determined. The method is first to reduce to the Crocco equation uu′′ + s = 0 and then to use an associated autonomous planar vector field. The most useful properties of Crocco solutions appear to be related to canard solutions of a slow fast vector field.

In September 2002 a flash flood killed 23 human lives and generated 1.2 billion Euros of damages in less than 24 hours over an area of 20 000 km2 located in the south of France. The Gard river basin was hit by a storm that locally received more than 600 mm in one day. This storm triggered catastrophic flash floods on many upstream tributaries as well as the most important flood ever reported of the major rivers (Gard, Ceze and Vidourle). The distributed prediction of such extreme events remains an open question due to scarcity of observations and the unknown individual hydrological behaviour of very small basins. Due to the high spatial and temporal variability of rainfall and of the physiographic conditions, physically-based distributed hydrological models offer perspective for the simulation of such flash-floods at a regional scale, and more specifically in small ungauged basins which are recognized as the most vulnerable. However, the evaluation of model performance for such events remains largely open. Traditional stream gauge networks provide estimate at only a few locations, and these values are very uncertain for large discharges. Indeed, stage discharge relationship are in general extrapolated far beyond gauged values -if they are not destroyed- for extreme floods. Alternative sources of data are therefore necessary for model evaluation. In this paper, such an alternative solution is presented and illustrated using data from the Gard September 2002 event. It consists in using a post flood field survey data set made of estimation of maximum peak discharge and time of peak. Such estimations are conducted at the regional scales for catchments of various sizes (for a few to about 100 km2) in areas affected by different rainfall amounts in order to sample a large range of hydrological responses. These estimations are derived from hydrological investigation using interviews of witnesses and river cross-sections surveys. The distributed modelling approach was implemented within the numerical modelling LIQUID platform on the Cévennes Vivarais region. The model is based on a spatial discretization in hydrolandscapes determined using the overlay of the sub-catchments map and the pedology map. Information taken from an existing soil data base about soil profiles structure and hydraulic properties deduced from pedo-transfer function were used to describe soil characteristics. The first version of the model, includes a representation of infiltration (Richards equation) on the hydro-landscapes, a calculation of the surface flux towards the nearest river reach and flow routing in the river network based on the kinematic wave approximation of the St-Venant equation. The model, forced using re-processed radar data at a 5min and 1 km2 resolution, was set up on 19 sub-catchments where post-flood maximum peak discharge estimation were available. Their size range from about 2 to 100 km2. Model estimates of maximum peak discharge were found to be in fair agreement with post flood field estimates. The observed maximum specific discharge versus catchment area relationship was also correctly simulated. This first example shows the value of post-flood field survey, combined with high resolution radar rainfall for improving our prediction capacity of extreme floods events.

Purpose: Regionalised characterisation factors (CFs) for watersheds around the world are available to assess water-use-related environmental impacts. The main problem with using the watershed regionalisation level arises when a single CF is generated for large watersheds in countries where water availability and demand are not uniform. Additionally, water availability and use vary over time because of the effects of climate change and changing human lifestyles. These two factors are currently not taken into account in CFs, but should be included for the sake of the accuracy of LCA results. The aim of this research was to provide water stress index CFs at the sub-watershed spatial level for three temporal scenarios (present, short-term future and mid-term future) for Spain (Southern Europe), a country with considerably variability in water availability that is especially vulnerable to climate change effects. Methods: CFs were calculated following the water stress index (WSI) definition of Pfister et al. (2009). The WSI was calculated on a yearly basis for 117 sub-watersheds - compared to 56 regionalisation units provided in the original method - and for (i) the current situation: current water use and availability; (ii) short-term future: projections for 2015; and (iii) mid-term future: projections for 2030. The uncertainties of the CFs were calculated for each sub-watershed. Results and discussion: Temporal trend analysis of the CFs showed a general relaxation of water stress over the short-term when compared to the current situation, followed by a new increase. Major differences were noticed in the WSIs calculated by Pfister et al. (2009) using global data and maps and the WSIs calculated in this study using national and regional data. The WSIs under consideration of uncertainty were higher than the deterministic result for intermediate WSIs. Conclusions and outlook: The CFs generated are useful compared with the CFs previously available because they improve evaluation of the water-use-related impacts of present and future technologies with the life cycle stages located in Spain. We encourage LCA developers to update WSIs for other countries using information at the national level that is usually freely accessible. / Dans l'Analyse de Cycle de Vie (ACV), il y a des facteurs de caractérisation (FC) à l'échelle du bassin-versant pour le monde entier et basés sur des données des années 1990. Dans ce travail, des facteurs de caractérisation de stress hydrique à l'échelle du sous-bassin versant pour trois scénarios temporels (présent, futur à court terme et futur à moyen terme) ont été développés pour l'Espagne.

This paper focuses on residential sorting by social and ethnic status in large French urban areas. Three major determinants of segregation are stressed in the economic literature (i) Alonso sorting based on distance, due to the trade-off between land consumption and accessibility to the central city, (ii) sorting based on local households' income, due to the taste for endogenous amenities produced by residents' income and (iii) Tiebout sorting over jurisdictions, due to the taste for local public goods. The last two mechanisms result in an interjurisdictional sorting according to jurisdiction's average household income, while the first one leads to a radioconcentric sorting. Our objective is to assess the relative importance of these two types of sorting. Our methodology draws on Schmidheiny (2006). First, a conditional logit model is estimated for each urban area, in which moving households are assumed to sort based on jurisdictions' distance to the central city and jurisdictions' mean household income (as a proxy for the level of endogenous amenities and local public goods). Second, our estimation results are used to simulate the counterfactual residential patterns that would prevail if, alternatively, one or the other of these segregation channels were inactive. The contribution of the two types of sorting to the social and ethnic segregation is finally appreciated by comparing the values of dissimilarity indexes computed on the basis of the observed and counterfactual residential distributions of households. Interjurisdictional sorting based on income emerges as the primary cause of social segregation among wage-earning households. On the contrary, Alonso-type sorting appears to be the main driver of segregation between economically active and inactive households, as well as between French-citizen and Foreign-citizen households.