10,778 research outputs found
Flash floods in the french mediterranean region ; toward transfer methodologies for ungauged catchments
No full textD’un point de vue climatique la région méditerranéenne est propice aux évènements pluvio-orageux intenses, particulièrement en automne. Ces pluies s’abattent sur des bassins versants escarpés. La promptitude des crues ne laisse qu’un temps très court pour la prévision. L’amplitude de ces crues dépend de la grande variabilité des pluies et des caractéristiques des bassins versants. Les réseaux d'observations ne sont habituellement pas adaptés à ces petites échelles spatiales et l'intensité des événements affecte souvent la fiabilité des données quand elles existent d’où l’existence de bassin non jaugés. La régionalisation en hydrologie s’attache à la détermination de variables hydrologiques aux endroits où ces données manquent. L’objectif de cette thèse est de contribuer à poser les bases d’une méthodologie adaptée à la transposition des paramètres d'un modèle hydrologique distribué dédié aux crues rapides de bassins versants bien instrumentés à des bassins versants non jaugés, et ce sur une large zone d’étude. L’outil utilisé est le modèle hydrologique distribué MARINE [Roux et al., 2011] dont l’une des originalités est de disposer d’un modèle adjoint permettant de mener à bien des calibrations et des analyses de sensibilité spatio-temporelles qui servent à améliorer la compréhension des mécanismes de crue et à l’assimilation de données en temps réel pour la prévision. L’étude des sensibilités du modèle MARINE aborde la compréhension des processus physiques. Une large gamme de comportements hydrologiques est explorée. On met en avant quelques types de comportements des bassins versants pour la région d’étude [Garambois et al., 2012a]. Une sélection des évènements de calibration et une technique de calibration multi évènements aident à l’extraction d’un jeu de paramètres par bassin versant. Ces paramétrisations sont testées sur des évènements de validation. Une méthode de décomposition de la variance des résultats conduit aux sensibilités temporelles du modèle à ses paramètres. Cela permet de mieux appréhender la dynamique des processus physiques rapides en jeu lors de ces crues [Garambois et al., 2012c]. Les paramétrisations retenues sont transférées à l’aide de similarités hydrologiques sur des bassins versants non jaugés, à des fins de prévision opérationnelleClimate and orography in the Mediterranean region tend to promote intense rainfalls, particularly in autumn. Storms often hit steep catchments. Flood quickness only let a very short time lapse for forecasts. Peak flow intensity depends on the great variability of rainfalls and catchment characteristics. As a matter of facts, observation networks are not adapted to these small space-time scales and event severity often affects data fiability when they exist thus the notion of ungauged catchment emerges. Regionalization in hydrology seeks to determine hydrological variables at locations where these data lack. This work contributes to pose the bases of a methodology adapted to transpose parameterizations of a flash flood dedicated distributed hydrologic model from gauged catchments to ungauged ones, and for a large study area. The MARINE distributed hydrologic model is used [Roux et al., 2011], its originality lies in the automatically differentiated adjoint model able to perform calibrations and spatial-temporal sensitivity analysis, in order to improve understanding in flash flood generating mechanisms and real time data assimilation for hydrometeorological forecasts. MARINE sensitivity analysis addresses the question of physical process understanding. A large panel of hydrologic behaviours is explored. General catchment behaviours are highlighted for the study area [Garambois et al., 2012a]. Selected flood events and a multiple events calibration technique help to extract catchment parameter sets. Those parameterizations are tested on validation events. A variance decomposition method leads to parameter temporal sensitivity analysis. It enables better understanding in catching dynamics of physical processes involved in flash floods formation [Garambois et al., 2012c]. Parameterizations are then transfered from gauged catchments with hydrologic similarity to ungauged ones with a view to develop real time flood forecastin
Étude régionale des crues éclair de l'arc méditerranéen français ; élaboration de méthodologies de transfert à des bassins versants non jaugés
No full textD'un point de vue climatique la région méditerranéenne est propice aux évènements pluvio-orageux intenses, particulièrement en automne. Ces pluies s'abattent sur des bassins versants escarpés. La promptitude des crues ne laisse qu’un temps très court pour la prévision. L'amplitude de ces crues dépend de la grande variabilité des pluies et des caractéristiques des bassins versants. Les réseaux d'observations ne sont habituellement pas adaptés à ces petites échelles spatiales et l'intensité des événements affecte souvent la fiabilité des données quand elles existent d'où l'existence de bassin non jaugés. La régionalisation en hydrologie s'attache à la détermination de variables hydrologiques aux endroits où ces données manquent. L'objectif de cette thèse est de contribuer à poser les bases d’une méthodologie adaptée à la transposition des paramètres d'un modèle hydrologique distribué dédié aux crues rapides de bassins versants bien instrumentés à des bassins versants non jaugés, et ce sur une large zone d’étude. L'outil utilisé est le modèle hydrologique distribué MARINE [Roux et al., 2011] dont l'une des originalités est de disposer d'un modèle adjoint permettant de mener à bien des calibrations et des analyses de sensibilité spatio-temporelles qui servent à améliorer la compréhension des mécanismes de crue et à l'assimilation de données en temps réel pour la prévision. L'étude des sensibilités du modèle MARINE aborde la compréhension des processus physiques. Une large gamme de comportements hydrologiques est explorée. On met en avant quelques types de comportements des bassins versants pour la région d'étude [Garambois et al., 2012a]. Une sélection des évènements de calibration et une technique de calibration multi évènements aident à l'extraction d'un jeu de paramètres par bassin versant. Ces paramétrisations sont testées sur des évènements de validation. Une méthode de décomposition de la variance des résultats conduit aux sensibilités temporelles du modèle à ses paramètres. Cela permet de mieux appréhender la dynamique des processus physiques rapides en jeu lors de ces crues [Garambois et al., 2012c]. Les paramétrisations retenues sont transférées à l'aide de similarités hydrologiques sur des bassins versants non jaugés, à des fins de prévision opérationnelle
“Enquête sur l’auteur. Entretien avec Pierre Bayard”
No full textInternational audience05/04/2019 “Enquête sur l’auteur. Entretien avec Pierre Bayard” [“Investigation into the Author. Interview with Pierre Bayard”], event for bachelor’s and master’s students in French and comparative literature, Lorraine University
Learning river properties and infering river discharge from SWOT-like data time-series
No full textNew generations of satellites and sensors offer promising possibilities to overcome the lack of in situ data for hydrological sciences, with increasing spatio-temporal coverage and accuracy ([1, 2]). Nevertheless, inverse problems in hydraulics such as the estimation of river discharges from space are still open questions. Remotely sensed measurements of hydrosystems can provide valuable information but adequate methods are still required to take maximum advantage of it. Lots of studies have shown the possibility of retrieving discharge given the river bathymetry or roughness and/or in situ time series. The new challenge is to use SWOT-type data (that is to say water surface elevation, free surface slope and top width) to inverse the triplet formed by the roughness, the bathymetry and the discharge (A0,K,Q) ([3]). We show that the most complete shallow-water like model allowing to separate the roughness and bathymetry terms is the so-called low Froude model. The few inverse models elaborated for inferring (A0,K,Q) are analyzed in two contexts: 1) only remotely sensed observations of the water surface (surface elevation, width and slope) are available ; 2) one additional water depth measurement (or estimate) is available. Results of hydraulic parameters inversions will be presented for a large dataset of rivers with contrasted properties, in the context of the PEPSI challenge that is an intercomparison project of several discharge inversion methods using SWOT-like data ([4, 5, 3]). Considering effective hydraulic parameterizations (e.g. [6, 7]), depending on observation scale, several perspectives are discussed for data assimilation into 1D and 2D hydraulic models. The temporal sampling of a mission such as SWOT will offer new possibilities in terms of hydraulic visibility for describing and learning river reaches, floodplains, and hydrosystems behaviours. References [1] S. Calmant, F. Seyler, and J. Cretaux, Monitoring continental surface waters by satellite altimetry, Surveys in Geophysics, vol. 29, no. 4-5, pp. 247-269, 2008. [2] D. E. Alsdorf and D. P. Lettenmaier, Tracking fresh water from space, Science, vol. 301, no. 5639, pp. 1491-1494, 2003. [3] P.-A. Garambois and J. Monnier, Inference of effective river properties from remotely sensed observations of water surface, Advances in Water Resources, vol. 79, pp. 103-120, 2015. [4] M. Durand, J. Neal, E. Rodriguez, K. M. Andreadis, L. C. Smith, and Y. Yoon, Estimating reach-averaged discharge for the river severn from measurements of river water surface elevation and slope, Journal of Hydrology, vol.-, no. 0, pp., 2014. [5] C. J. Gleason, L. C. Smith, and J. Lee, Retrieval of river discharge solely from satellite imagery and at-many-stations hydraulic geometry: Sensitivity to river form and optimization parameters, Water Resources Research, vol. 50, no. 12, pp. 9604-9619, 2014. [6] P.-A. Garambois, S. Calmant, H. Roux, A. Paris, J. Monnier, and J. Santos da Silva, Hydraulic visibility and effective cross sections based on hydrodynamical modeling of flow lines gained by satellite altimetry,(submitted), 2015. [7] A. Paris, R. C. Paiva, J. Santos Da Silva, D. Moreira, S. Calmant, P.-A. Garambois, W. Collischonn, M.-P. Bonnet, and F. Seyler, Stage-discharge rating curves based on satellite altimetry and modelled discharge in the amazon basin, Water Ressources Research, revised
Retrieving river discharge from SWOT-like data time-series : a sample of rivers types
No full textThe future SurfaceWater and Ocean Topography (SWOT) mission would provide new cartographic measurements of ocean surface and inland water surfaces dynamics, and especially river height, width and slope. The highlight of SWOT will be its almost global coverage and temporal revisits on the order of 1 to 4 times per 22 - days repeat cycle [1]. The estimation of hydraulic parameters from water surface observations is still an open question. Several methods have recently been proposed for retrieving river discharge from SWOT data ([2, 3, 4]). The method introduced by [2] and used in the present study is based on Manning equation. The first step consists in retrieving an equivalent bathymetry profile for a river given one in situ depth measurement and SWOT like data of the water surface, that is to say water elevation, free surface slope and width. From this equivalent bathymetry, the second step consists in solving mass and Manning equation in the least square sense. Nevertheless, for cases where no in situ measurement of water depth is available, it is still possible to solve a system formed by mass and Manning equations in the least square sense (or with other methods such as Bayesian ones, see e.g. [3]). The approach is tested with synthetic data generated from hydraulic models for several river reaches around the world (cf. [5]). We show that a good a priori knowledge of bathymetry and roughness is required for such methods. The identifiability of the roughness geometry couple is also investigated for different space time sampling and hydraulic regimes. Indeed, the knowledge of effective hydraulic representation and limitations might be a cornerstone in identifications of hydraulic or hydrologic variables through data assimilation chains. References : [1] E. Rodriguez, “SWOT science requirements document,” JPL document, JPL, 2012. [2] P. A. Garambois and J. Monnier, “Inference of river properties from remotly sensed observations of water surface,” (minor revisions) Advances in Water Ressources, 2014. [3] M. Durand, J. Neal, E. Rodriguez, K. M. Andreadis, L. C. Smith, and Y. Yoon, “Estimating reach-averaged discharge for the river severn from measurements of river water surface elevation and slope,” Journal of Hydrology,vol. -, no. 0, pp. –, 2014.[4] C. J. Gleason, L. C. Smith, and J. Lee, “Retrieval of river discharge solely from satellite imagery and atmanystations hydraulic geometry: Sensitivity to river form and optimization parameters,” Water Resources Research, pp. n/a–n/a, 2014. [5] M. Durand, L. Smith, C. Gleason, D. Bjerklie, P.-A. Garambois, and H. Roux, “Assessing swot discharge algorithms performance across a range of river types,” in AGU fall meeting, H51S-02, 201
Is There Market Power in the French Comte Cheese Market?
No full textAn NEIO approach is used to measure seller market power in the French Comté cheese market, characterised by government-approved supply control. The estimation is performed on quarterly data at the wholesale stage over the period 1985-2005. Three different elasticity shifters are included in the demand specification, and the supply equation accounts for the existence of the European dairy quota policy. The market power estimate is small and statistically insignificant. Monopoly is rejected, as well as weak forms of Cournot oligopoly. Results appear to be robust to the choice of functional form, and suggest little effect of the supply control scheme on consumer prices.Supply control, NEIO, protected designation of origin, Marketing,
Flash flood prediction at the regional scale and methodology for ungauged catchments
No full textClimate and orography in the Mediterranean region tend to promote intense rainfalls, particularly in autumn. Storms often hit steep catchments and flood quickness only let a very short time lapse for forecasts. Peak flow intensity depends on the great variability of rainfalls and catchment characteristics. As a matter of facts, observation networks are not adapted to these small space-time scales and event severity often affects data reliability when they exist thus the notion of ungauged catchment emerges. Regionalization in hydrology seeks to determine hydrological variables at locations where these data lack. This work contributes to pose the bases of a methodology adapted to transpose parameterizations of a flash flood dedicated distributed hydrologic model from gauged catchments to ungauged ones, and for a large study area. The MARINE distributed hydrologic model is used (Roux et al. 2011), its originality lies in the automatically differentiated adjoint model able to perform calibrations and spatial-temporal sensitivity analysis, in order to improve understanding in flash flood generating mechanisms and real time data assimilation for hydrometeorological forecasts. The first step for MARINE model regionalization is sensitivity analysis which addresses the question of physical process understanding. A large panel of hydrologic behaviours is explored. General catchment behaviours are highlighted for the study area (Garambois, Larnier, et al. 2013). Selected flood events and a multiple events calibration technique help to extract catchment parameter sets. Those parameterizations are tested on validation events and ensemble predictions are performed for a recent flood event. A variance decomposition method leads to parameter temporal sensitivity analysis. It enables better understanding in catching dynamics of physical processes involved in flash floods formation (Garambois, Roux, et al. 2013). Parameterizations are then transferred from gauged catchments with hydrologic similarity to ungauged ones with a view to develop real time flood forecasting
The aesthetics of Pierre Boulez
No full textTo enable the reader to find references as quickly and easily as possible, I have grouped all references together in the bibliography in alphabetical order. Texts by the same author are distinguished first by year and second, if there are several texts from the same year, by letter. Interviews and writing collaborations (including published correspondence) involving Boulez are also ordered alphabetically. The year given at the beginning of each bibliographical entry is, in the majority of cases, the year in which the text was first published (not necessarily the year of the edition cited). For all writings written by Boulez, I have provided the original title under which the text in question was first published (usually in French). Many articles have subsequently been translated into English and therefore I have decided to provide page references for both versions. For all texts by writers other than Boulez, I have cited the version of the text I have used. Wherever possible, I have cited the existing English translations of texts originally written in French. However, on many occasions I have considered it necessary to make alterations to the published translations. This is particularly applicable to Boulez on Music Today (1971) and Orientations (1986), both of which display an often heavy-handed and rather inaccurate approach to the task of translating specific concepts employed by Boulez. In contrast. Stocktakings of an Apprenticeship (1991) has required only occasional minor amendments. All changes to the published English translations are acknowledged in the corresponding footnote. None of the material m this thesis has previously been submitted for a degree in this or any other University. The copyright of this thesis rests with the author. No quotation from it should be published without prior written consent and information from it should be acknowledged. I have received permission to exceed the word limit from the Graduate School Committee at the University of Durham
Etnografia e fotografia: reflexões sobre as fotografias etnográficas de Pierre Fatumbi Verger
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-graduação em Antropologia Social, Florianópolis, 2009A relação entre a fotografia e a etnografia nos estudos da Antropologia, apesar de antiga e densa, é incerta e complexa. Se por um lado a fotografia é a cada dia mais utilizada nos trabalhos antropológicos, por outro sua potencialidade como algo além da ilustração e de uma técnica de interação com o Outro é pouco explorada. A partir do exemplo, do legado, da trajetória de vida e, principalmente, da obra de Pierre Fatumbi Verger, esta pesquisa se dedica a analisar essa relação. Francês radicado na Bahia na década de 1940, Verger é conhecido mundialmente tanto por seu trabalho como fotógrafo quanto pelas suas pesquisa etnográficas. Há, entretanto, uma indefinição quanto à razão desse reconhecimento, e examinar as suas razões oferece um profícuo campo de reflexão sobre a pesquisa etnográfica, especialmente quando relacionada ao universo das imagens fotográficas. A Fundação Pierre Verger é a instituição que atualmente abriga o acervo do fotógrafo-etnógrafo e onde foi realizada a pesquisa de campo através da qual, aliada à leitura de fotografias relacionadas ao candomblé em suas manifestações na África e na Bahia, foi criada uma metodologia de análise das fotografias que privilegia as interações e os diálogos como espaço de construção de definições sobre a etnografia. Pelo contato com a Fundação, seus freqüentadores e o acervo fotográfico ali disponibilizado, esta pesquisa pretende refletir sobre a etnografia e a construção de um olhar etnográfico em relação direta com o exercício da fotografia.The relationship between photography and ethnography in anthropological studies, albeit ancient and deep, is uncertain and complex. Photography has been increasingly used in anthropological researches but it´s potencial as something beyond illustration and it´s interaction with the Other as a technique is very little explored. This research is dedicated to the analysis of this relationship by taking the work of Pierre Fatumbi Verger, his life and legacy. A French man, rooted in Bahia, Brasil, in the decade of 1940, Verger is known worldwide for his work as a photographer as well as for his etnographic studies. However, the reason of this recognition is undefined and examining the reason for these indefinitions can be a fruitful field of reflection concerning ethnographic researches, especially when related to the photographic universe. The Pierre Verger Foundation is the institution that hosts his photographic and ethnographic collection and it´s also where the field research of this work took place. Through the field research combined with the readings of photographs related to candomblé and it´s manifestations in Africa and Bahia, a photographic analysis methodology was created that privilege interaction and dialogue as a way to build definitions about ethnography. By the contact with the Foundation, it´s users and it´s available photographic collection, this research intends to reflect about the ethnography and the creation of an ethnographic view in direct relation to the exercise of photography
Parameter Regionalization for a Process Oriented Distributed Model Dedicated to Flash Floods
No full textFlash flood is a very intense and quick hydrologic response of a catchment to rainfall. This phenomenon has a high spatial-temporal variability as its generating storm, often hitting small catchments (few km ² ). Consequently their prediction remains a hard exercise with the necessary data being often scarce. As defined by Sivapalan et al. (2003) prediction on ungauged catchments is one of the challenges of hydrological modelling, especially for flash flood. Several studies have been headed up with the MARINE model (Modélisation de l’Anticipation du Ruissellement et des Inondations pour des évèNements Extrêmes) for the Gard region (France), (Braud et al. 2010), (Castaings et al. 2009). This physically based spatially distributed rainfall runoff model is dedicated to flash flood prediction. The present contribution is a study about parameter sets regionalization for process oriented hydrological models in the case of flash floods. MARINE model performances are tested on 117 flash floods from the last two decades which is a large catalogue of hydrology and landscapes from Pyrenean, Mediterranean, Cévennes-Vivarais and Provence regions. Encouraging results are obtained with two similarity approaches. Only a small decrease of performances from calibration/ validation to regionalization is detected for these two methods. This study sheds more light on the importance of hydrological information that is available in calibration events for a gauged catchment or from donor catchment(s) for regionalization. It can also be shown that the most sensitive parameter of MARINE model (Garambois et al 2013) which is controlling the soil volume and water balance, is rather well constrained by the two similarity approaches thanks to bedrock descriptors.Garambois Pierre-André, Douinot Audrey, Roux Hélène, Dartus Denis. Parameter Regionalization for a Process Oriented Distributed Model Dedicated to Flash Floods. In: SimHydro 2014. New Trends in Simulation. 11-13 June 2014 Ecole Polytech’ Nice (France) 2014
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