This thesis investigates the characteristics and impacts of large wood accumulations within river reaches of different size and style. Four reaches were studied: (i) a wide, braided, headwater reach, characterised by dead wood (Tagliamento River, Italy); (ii) a lower gradient, wide, braided reach, characterised by resprouting wood (Tagliamento River, Italy); (iii) a low gradient, single thread reach with a natural supply of dead wood (Highland Water, UK), and (iv) a low gradient, single thread reach that has been restored by felling trees into the river (River Bure, UK). In each reach, quantities of wood, types of accumulation and their association with sediment retention, landform and propagule bank development were investigated, generating four main findings: 1. There were marked differences in the size and character of large wood accumulations among the four reaches. 2. Retention of fine sediment and organic matter by wood was observed on all four reaches, giving rise to notable spatial heterogeneity in surface sediments. 3. Sediment retention resulted in the development of different landforms among the four reaches. In the two multi-thread reaches, accretion of finer sediment around large wood led to island development. In the naturally-functioning single-thread reach, wood jams spanned the river channel, accumulating sediment and organic matter to produce unvegetated wood jams, and inducing other landforms, notably pools and bars. Such geomorphic heterogeneity was anticipated in the restored reach, but to date this has not significantly occurred. 4. Spatio-temporal variations were observed in propagule abundance and species richness within different wood-related mesohabitats. Higher abundance and species richness were associated with finer, more organic sediments retained within wood accumulations and related mesohabitats. In the restored reach such associations were not statistically significant, further indicating that responses to wood emplacement take longer than the 4 years since restoration. iv Overall, this research has strengthened the evidence concerning the differing nature of wood accumulations in rivers of different size and style, and it has demonstrated the importance of large wood for retaining organic matter and plant propagules, resources essential for riparian vegetation succession and for the success of river restoration efforts.

Através de perfis sísmicos de alta resolução (3,5 kHz), coletados entre os anos de 2009 e 2014, foi possível analisar o fundo e sub-fundo marinho da plataforma continental interna do Rio Grande Sul, mais especificamente em frente à desembocadura do estuário da Lagoa dos Patos. Estes dados permitiram observar anomalias acústicas caracterizadas como sendo uma resposta à presença de gás intersticial no sedimento. As acumulações foram identificadas com base na morfologia, dimensão, tipo de assinatura acústica e concentração aparente de gás. Assim, cinco formas distintas de gás raso foram reconhecidas: cortina de gás, blanking acústico, turbidez acústica, pináculo de turbidez e pluma intra-sedimentar. Tais estruturações se apresentaram isoladas ou então relacionadas umas com as outras. Dentre estas, as cortinas de gás e blanking acústico foram as que ocorreram em maior número e área. As cortinas apresentaram morfologia bem definida, em formato de caixa, onde o gás se encontra mais concentrado. O blanking acústico, formado pela presença de bolhas de gás bem disseminadas no sedimento, foi distinguido por uma forte reflexão de topo e um mascaramento dos refletores subjacentes, sem demonstrar limites laterais bem definidos A turbidez acústica, associada à disseminação de gás moderada a alta, é uma perturbação de sinal pela presença de bolhas no sedimento em quantidades que apenas atenuam a energia sísmica, possibilitando identificar algum refletor abaixo do seu topo. Os pináculos de turbidez encontrados são pequenos e apresentaram forma pontiaguda, indicando uma disseminação de gás baixa a moderada. A pluma intra-sedimentar encontrada apresentou formato quase parabólico, interpassando a camada de sedimentos de modo que o gás presente nela é baixo a moderadamente disseminado. Tais formas estão diretamente ligadas com a distribuição das fácies sedimentares, as quais agem como reservatório e selante, retendo ou não o gás e gerando as diferentes respostas acústicas. A ocorrência do gás está concentrada em frente à desembocadura da Lagoa dos Patos, local de deposição de sedimentos finos e matéria orgânica. Este aporte lagunar e o retrabalhamento da plataforma por eventos de regressão e transgressão marinha no Quaternário permitiram a gênese e preservação do gás em sedimentos holocênicos, de provável origem biogênica. / Using high-resolution (3.5 kHz) seismic profiles collected between 2009 and 2014, it was possible to analyze the bottom and sub-bottom geoacoustics characteristics of the inner continental shelf of the Rio Grande Sul, more specifically in front of the mouth of the estuary of the Patos Lagoon. The data allowed observing acoustic anomalies characterized like being a response to gas presence in the sediment. The gas accumulations were identified based on their morphology, dimension, type of acoustic signature and apparent concentration of gas. Thus, five different features of shallow gas were recognized: gas curtain, acoustic blanking, acoustic turbidity zone, turbidity pinnacle and intra-sedimentary plume. These structures have been isolated or then related each other. Among these, the gas curtain and acoustic blanking were those that occurred in greater number and area. Gas curtains presented well defined morphology, in gas boxes format, where the gas is more concentrated. Acoustic blacking, originated from presence of well disseminated gas bubbles in the sediment, was distinguished by a strong top reflection that masks the below reflectors, without to show well defined lateral limits Acoustic turbidity zone, associated with the dissemination of moderate to high gas, is a signal disturbance due to the presence of bubbles in the sediment in quantities that only attenuate the seismic energy, allowing yet identifying some reflector below its top. Turbidity pinnacles found are small and present pointed shape, indicating to a low to moderated gas dissemination. Intra-sedimentary plume found presented an almost parabolic shape, penetrating across the sediment layer thus the gas dissemination in the plume is low to moderate. These forms are linked directly with the sedimentary facies distribution, which act like reservoir and sealant, retaining or not the gas and producing the distinct acoustic response. The gas is concentrated in front of the mouth of Patos Lagoon, deposition site of fine sediments and organic matter. Such lagoon sediment input and the reworking of the shelf by marine regression and transgression events during Quaternary allowed the genesis and preservation of gas occurring in the Holocene sediments, which origin is probable biogenic.

Através de perfis sísmicos de alta resolução (3,5 kHz), coletados entre os anos de 2009 e 2014, foi possível analisar o fundo e sub-fundo marinho da plataforma continental interna do Rio Grande Sul, mais especificamente em frente à desembocadura do estuário da Lagoa dos Patos. Estes dados permitiram observar anomalias acústicas caracterizadas como sendo uma resposta à presença de gás intersticial no sedimento. As acumulações foram identificadas com base na morfologia, dimensão, tipo de assinatura acústica e concentração aparente de gás. Assim, cinco formas distintas de gás raso foram reconhecidas: cortina de gás, blanking acústico, turbidez acústica, pináculo de turbidez e pluma intra-sedimentar. Tais estruturações se apresentaram isoladas ou então relacionadas umas com as outras. Dentre estas, as cortinas de gás e blanking acústico foram as que ocorreram em maior número e área. As cortinas apresentaram morfologia bem definida, em formato de caixa, onde o gás se encontra mais concentrado. O blanking acústico, formado pela presença de bolhas de gás bem disseminadas no sedimento, foi distinguido por uma forte reflexão de topo e um mascaramento dos refletores subjacentes, sem demonstrar limites laterais bem definidos A turbidez acústica, associada à disseminação de gás moderada a alta, é uma perturbação de sinal pela presença de bolhas no sedimento em quantidades que apenas atenuam a energia sísmica, possibilitando identificar algum refletor abaixo do seu topo. Os pináculos de turbidez encontrados são pequenos e apresentaram forma pontiaguda, indicando uma disseminação de gás baixa a moderada. A pluma intra-sedimentar encontrada apresentou formato quase parabólico, interpassando a camada de sedimentos de modo que o gás presente nela é baixo a moderadamente disseminado. Tais formas estão diretamente ligadas com a distribuição das fácies sedimentares, as quais agem como reservatório e selante, retendo ou não o gás e gerando as diferentes respostas acústicas. A ocorrência do gás está concentrada em frente à desembocadura da Lagoa dos Patos, local de deposição de sedimentos finos e matéria orgânica. Este aporte lagunar e o retrabalhamento da plataforma por eventos de regressão e transgressão marinha no Quaternário permitiram a gênese e preservação do gás em sedimentos holocênicos, de provável origem biogênica. / Using high-resolution (3.5 kHz) seismic profiles collected between 2009 and 2014, it was possible to analyze the bottom and sub-bottom geoacoustics characteristics of the inner continental shelf of the Rio Grande Sul, more specifically in front of the mouth of the estuary of the Patos Lagoon. The data allowed observing acoustic anomalies characterized like being a response to gas presence in the sediment. The gas accumulations were identified based on their morphology, dimension, type of acoustic signature and apparent concentration of gas. Thus, five different features of shallow gas were recognized: gas curtain, acoustic blanking, acoustic turbidity zone, turbidity pinnacle and intra-sedimentary plume. These structures have been isolated or then related each other. Among these, the gas curtain and acoustic blanking were those that occurred in greater number and area. Gas curtains presented well defined morphology, in gas boxes format, where the gas is more concentrated. Acoustic blacking, originated from presence of well disseminated gas bubbles in the sediment, was distinguished by a strong top reflection that masks the below reflectors, without to show well defined lateral limits Acoustic turbidity zone, associated with the dissemination of moderate to high gas, is a signal disturbance due to the presence of bubbles in the sediment in quantities that only attenuate the seismic energy, allowing yet identifying some reflector below its top. Turbidity pinnacles found are small and present pointed shape, indicating to a low to moderated gas dissemination. Intra-sedimentary plume found presented an almost parabolic shape, penetrating across the sediment layer thus the gas dissemination in the plume is low to moderate. These forms are linked directly with the sedimentary facies distribution, which act like reservoir and sealant, retaining or not the gas and producing the distinct acoustic response. The gas is concentrated in front of the mouth of Patos Lagoon, deposition site of fine sediments and organic matter. Such lagoon sediment input and the reworking of the shelf by marine regression and transgression events during Quaternary allowed the genesis and preservation of gas occurring in the Holocene sediments, which origin is probable biogenic.

Através de perfis sísmicos de alta resolução (3,5 kHz), coletados entre os anos de 2009 e 2014, foi possível analisar o fundo e sub-fundo marinho da plataforma continental interna do Rio Grande Sul, mais especificamente em frente à desembocadura do estuário da Lagoa dos Patos. Estes dados permitiram observar anomalias acústicas caracterizadas como sendo uma resposta à presença de gás intersticial no sedimento. As acumulações foram identificadas com base na morfologia, dimensão, tipo de assinatura acústica e concentração aparente de gás. Assim, cinco formas distintas de gás raso foram reconhecidas: cortina de gás, blanking acústico, turbidez acústica, pináculo de turbidez e pluma intra-sedimentar. Tais estruturações se apresentaram isoladas ou então relacionadas umas com as outras. Dentre estas, as cortinas de gás e blanking acústico foram as que ocorreram em maior número e área. As cortinas apresentaram morfologia bem definida, em formato de caixa, onde o gás se encontra mais concentrado. O blanking acústico, formado pela presença de bolhas de gás bem disseminadas no sedimento, foi distinguido por uma forte reflexão de topo e um mascaramento dos refletores subjacentes, sem demonstrar limites laterais bem definidos A turbidez acústica, associada à disseminação de gás moderada a alta, é uma perturbação de sinal pela presença de bolhas no sedimento em quantidades que apenas atenuam a energia sísmica, possibilitando identificar algum refletor abaixo do seu topo. Os pináculos de turbidez encontrados são pequenos e apresentaram forma pontiaguda, indicando uma disseminação de gás baixa a moderada. A pluma intra-sedimentar encontrada apresentou formato quase parabólico, interpassando a camada de sedimentos de modo que o gás presente nela é baixo a moderadamente disseminado. Tais formas estão diretamente ligadas com a distribuição das fácies sedimentares, as quais agem como reservatório e selante, retendo ou não o gás e gerando as diferentes respostas acústicas. A ocorrência do gás está concentrada em frente à desembocadura da Lagoa dos Patos, local de deposição de sedimentos finos e matéria orgânica. Este aporte lagunar e o retrabalhamento da plataforma por eventos de regressão e transgressão marinha no Quaternário permitiram a gênese e preservação do gás em sedimentos holocênicos, de provável origem biogênica. / Using high-resolution (3.5 kHz) seismic profiles collected between 2009 and 2014, it was possible to analyze the bottom and sub-bottom geoacoustics characteristics of the inner continental shelf of the Rio Grande Sul, more specifically in front of the mouth of the estuary of the Patos Lagoon. The data allowed observing acoustic anomalies characterized like being a response to gas presence in the sediment. The gas accumulations were identified based on their morphology, dimension, type of acoustic signature and apparent concentration of gas. Thus, five different features of shallow gas were recognized: gas curtain, acoustic blanking, acoustic turbidity zone, turbidity pinnacle and intra-sedimentary plume. These structures have been isolated or then related each other. Among these, the gas curtain and acoustic blanking were those that occurred in greater number and area. Gas curtains presented well defined morphology, in gas boxes format, where the gas is more concentrated. Acoustic blacking, originated from presence of well disseminated gas bubbles in the sediment, was distinguished by a strong top reflection that masks the below reflectors, without to show well defined lateral limits Acoustic turbidity zone, associated with the dissemination of moderate to high gas, is a signal disturbance due to the presence of bubbles in the sediment in quantities that only attenuate the seismic energy, allowing yet identifying some reflector below its top. Turbidity pinnacles found are small and present pointed shape, indicating to a low to moderated gas dissemination. Intra-sedimentary plume found presented an almost parabolic shape, penetrating across the sediment layer thus the gas dissemination in the plume is low to moderate. These forms are linked directly with the sedimentary facies distribution, which act like reservoir and sealant, retaining or not the gas and producing the distinct acoustic response. The gas is concentrated in front of the mouth of Patos Lagoon, deposition site of fine sediments and organic matter. Such lagoon sediment input and the reworking of the shelf by marine regression and transgression events during Quaternary allowed the genesis and preservation of gas occurring in the Holocene sediments, which origin is probable biogenic.

A spectral shallow water model is used at the 850 mb level to investigate the effects of cyclonic vorticity on heating in the lower troposphere and how this in turn causes an increase in cyclonic vorticity generation, creating a nonlinear vorticity feedback mechanism. The model is initialized with NCEP-NCAR reanalysis data from the period 1990-2003 and then used to simulate a heating forcing function centered in east Africa. The model is simulated using a Gaussian damped basic state, a zonally symmetric basic state, and a zero basic state. The heating forcing function is applied to these different basic states with a scaled mass sink to simulate heating in the atmosphere. The heating forcing function creates a vorticity feedback mechanism that increases cyclonic vorticity. The analysis of these different basic states shows that the Gaussian damped basic state reduces the amplitude of the observational fields at the poles, increases the observational fields in the tropical region and increases the stability of the model at shallow depths. The zero basic state does have a significant effect on cyclonic vorticity generation, but does not improve the capability of the wave to propagate westward into the Atlantic Ocean. The zonally symmetric basic state succeeds in increasing the amount of cyclonic vorticity generated. The zonally symmetric basic state, once the vorticity non-feedback region is extended, is also very effective at increasing the amount of cyclonic vorticity generated and increasing the propagation of this wave westward into the Atlantic Ocean. The analysis suggests that the vorticity feedback mechanism created by the heating forcing function is affected by cyclonic vorticity when a zero and zonally symmetric basic state are used.

Made available in DSpace on 2015-05-14T12:09:46Z (GMT). No. of bitstreams: 1 parte1.pdf: 2267070 bytes, checksum: 551290d15ac745e0d27f56da50c62585 (MD5) Previous issue date: 2006-12-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The growth of cities and the appearance of occupations of disordered form are great problems to be faced by the Public Power. The maintenance of welfare conditions of the population doesn t develop in the same speed that the accumulations appear, that it makes impracticable adequately efficient solutions to the infrastructure demands and public services. The not-attendance of these demands allows that the population develops inadequate solutions, being able to generate great impacts to the environment and the welfare of everyone. In regards to the solid residues, the national scene is preoccupying. The majority of the Brazilian cities still destine its garbage of inadequate form, in garbage place. Although the cities not to possess budget adjusted to accomplishment of regular and efficient services of public cleanness, the population also doesn t contribute, developing inadequate habits in the handling of the solid residues. The study allows to verify the conditions that find the inserted urban accumulations in the basin of river Gramame. It can be perceived that in the majority of the studied accumulations the service of regular urban cleanness is developed. However, some inhabitants of that place don t adopt the collection, destining the garbage of inadequate form. In the accumulations that don t make use of the service, the adopted solutions are the burning, to embed the residue or simply to destine it on the ground. Although the communities possess associations, the actions of reduction and reuse of residues are spread out of discrete form. After evaluation of the partner-economic and ambient aspects of the studied accumulations, verified which of these is the most deficit if treating existing demands and was proposal an alternative of management of the solid residues, being able to be used in the others inserted accumulations in the basin or of other regions, with similar characteristics. / O crescimento das cidades e o aparecimento de ocupações de forma desordenada são grandes problemas a serem enfrentados pelo Poder Público. A manutenção das condições de bem estar da população não se desenvolve na mesma velocidade em que surgem os aglomerados, o que inviabiliza soluções adequadamente eficientes às demandas de infraestrutura e serviços públicos. O não atendimento destas demandas permite que a população desenvolva soluções inadequadas, podendo gerar grandes impactos ao meio ambiente e ao bem estar de todos. No tocante aos resíduos sólidos, o cenário nacional é preocupante. A maioria dos municípios brasileiros ainda dispõe seu lixo de forma inadequada, em lixões. Apesar das cidades não possuírem orçamento adequado para a realização de serviços de limpeza pública regulares e eficientes, a população também não contribui, desenvolvendo hábitos inadequados no manejo dos resíduos sólidos. O estudo permite verificar as condições em que se encontram os aglomerados urbanos inseridos na bacia do Rio Gramame. Pode-se perceber que na maioria dos aglomerados estudados o serviço de limpeza urbana regular é desenvolvido. Todavia, alguns moradores daqueles não adotam a coleta, destinando o lixo de forma inadequada. Nos aglomerados que não dispõem do serviço, as soluções adotadas são a queima, enterrar o resíduo ou simplesmente destiná-lo ao céu aberto. Apesar das comunidades possuírem associações, as ações de redução e reaproveitamento de resíduos são difundidas de forma discreta. Após avaliação dos aspectos sócio-econômicos e ambientais dos aglomerados estudados, verificou-se qual destes é o mais deficitário quanto às demandas existentes e fora proposta uma alternativa de gerenciamento dos resíduos sólidos, podendo ser utilizada nos demais aglomerados inseridos na bacia ou de outras regiões, com características semelhantes.

Les systèmes sédimentaires turbiditiques présentent un double intérêt académique et industriel puisqu’ils constituent à la fois des archives des conditions environnementales et des réservoirs pétroliers potentiels. Parmi les nombreux paramètres contrôlant l’organisation sédimentaire de ces systèmes l’inclinaison de la pente continentale apparait être un paramètre majeur. L’analyse de l’influence de l’inclinaison de la pente et de ces variations sur l’hydrodynamique des écoulements sédimentaires et ainsi sur l’architecture des systèmes turbiditiques revêt un caractère crucial tant du point de vue académique que pétrolier. Ce travail s’appuie sur l’analyse haute résolution de données acoustiques (bathymétrie, imagerie multifaisceaux, sismique THR, sonar latéral) acquises sur la marge abrupte du Golfe de Gênes (Malisar, Fables, Prisme, Gelo) et de l’analyse d’un bloc de sismique 3D sur la marge abrupte Ivoirienne. Les accumulations turbiditiques des deux sites témoignent de processus de ségrégation des particules avec le piégeage des particules les plus grossières dans des structures en plunge pools, cyclic steps ou slope break deposits. L’étude fine de ces corps liés au ressaut hydraulique apporte ici un éclairage inédit sur la continuité des corps sableux à la transition canyon/lobe et permet ainsi de proposer un nouveau scénario de modèle réservoir. De plus l’analyse de ces deux zones d’études met en évidence l’impact direct de l’activité tectonique sur l’architecture des accumulations turbiditiques par la mise en place et le maintien d’une zone de rupture de pente où le phénomène de ressaut hydraulique peut perdurer au cours du temps. / Turbidite systems present both academic and industrial interests since they are archives of environmental conditions and potential oil reservoirs. Among many parameters controlling the sedimentary organization, the continental slope inclination appears to be a major parameter. The analysis of slope inclination’s and these variations on the hydrodynamic of sedimentary flows and thus on turbidite systems architecture is a crucial character for both academic and industrial interests. The Pliocene-Quaternary turbidite systems of the Gulf of Genoa and upper margin of the Ivorian Cretaceous develop on margins with steep slope profiles controlled by tectonic processes and are suitable and complementary items for the Study of turbidite sedimentation in context of abrupt margin. This work is based on the high-resolution analysis of acoustic data (bathymetry, multibeam imaging, seismic THR, sidescan sonar) acquired on the steep margin of the Gulf of Genova (Malisar, Fables, Prism, Gelo) and the analysis of a 3D seismic block on the Ivorian steep margin. Turbidite accumulations of two sites demonstrate particle segregation processes with trapping coarser particles into specific structures such as plunge pools and cyclic steps. The detailed study of these bodies related to hydraulic jump sheds a new light on the continuity of sand bodies in the transition canyon / lobe and allows the designing of a new reservoir model scenario. Further analysis of these two areas of study shows the direct impact of tectonic activity on the architecture of turbidite accumulations by establishing and maintaining a nick area where the phenomenon of hydraulic jump can be maintained over time.

O surgimento da Lei do Petróleo, Lei 9.478/97, abriu uma nova frente de investimentos para o capital privado. O setor de exploração e produção de petróleo, antes sob monopólio estatal, passou a ser de interesse de diversas empresas privadas. Com a supervisão da ANP, surgiram as rodadas de licitações para concessão do direito de exploração e produção de petróleo dos campos ofertados. Os campos maduros e marginais foram então uma oportunidade de fomento aos negócios de petróleo devido à necessidade de uma operação mais eficiente, porém exigindo menores investimentos e necessidade técnica específica. Esta dissertação tem por objetivo expor o panorama econômico do setor de exploração e produção de petróleo para pequenas e médias empresas que atuam na região da Bacia Potiguar, Rio Grande do Norte, a partir de pesquisas e levantamentos de dados sobre: os conceitos teóricos de campos marginais e maduros e de pequenas e médias empresas; o histórico brasileiro de produção independente de petróleo; a geografia física e humana da Bacia Potiguar; e as barreiras econômicas encontradas por pequenas e médias empresas que atuam no setor de exploração e produção de petróleo. Depois de apresentadas e justificadas todas as hipóteses, são realizadas simulações de diferentes cenários para análise da viabilidade de um empreendimento de reativação de um campo marginal de petróleo. Utilizando a metodologia de fluxo de caixa descontado, foi possível avaliar o Valor Presente Líquido, Taxa Interna de Retorno e Payback do empreendimento. A partir da análise do fluxo de caixa e da sensibilidade de algumas premissas, avaliou-se o comportamento do Valor Presente Líquido do empreendimento em função das mudanças do preço de venda do barril de petróleo, do volume de produção do campo e de outros parâmetros escolhidos. Por fim, foi feita uma comparação entre trabalhos cujos autores propuseram temas semelhantes, para efeito de comparação e comprovação da sensibilidade e viabilidade dos campos. / The emergence of the Petroleum Law, Law 9.478/97, opened a new investment front for private capital. The upstream sector, previously under state monopoly, became a focus of interest from several private companies. With the supervision of the ANP, came rounds of bidding to grant exploration and production rights to the available oil fields. Mature and marginal fields were then a development opportunity in the oil business due to the need for a leaner operation, while requiring less investment and specific technical necessity. This thesis aims to expose the economic outlook of the onshore upstream sector for small and medium-sized companies operating in the Potiguar Basin region, Rio Grande do Norte, based on research and data surveys about: the theoretical concepts of marginal and mature fields and small and medium companies; the history of Brazilian independent oil production; the physical and human geography of the Potiguar Basin as well as the economic barriers faced by small and medium-sized companies operating in the oil exploration and production sector. After the presentation and justification of all hypotheses, simulations are carried out with different scenarios for analyzing the feasibility of the reactivation of a marginal oil field. Using the discounted cash flow method, it was possible to evaluate the Net Present Value, Internal Rate of Return and Payback of the project. From the analysis of cash flow and the sensitivity of some assumptions, we evaluated the behavior of the Net Present Value due to the sale price changes of the oil barrel, the volume of oil production in the field and other chosen parameters. Finally, a comparison between other papers whose authors have proposed similar themes was made, for comparison and verification of the sensitivity and viability of the fields.

L'évolution des paysages provençaux (sud Luberon, Vaucluse, France) depuis la dernière glaciation est analysée au travers de la dynamique couplée des formations alluviales et des systèmes travertineux, en relation avec les changements climatiques et l'anthropisation. Des analyses géomorphologiques, sedimento-stratigraphiques et physico-chimiques, dont les résultats sont incrémentés par des études archéologiques et paléoécologiques (malacologie et anthracologie) ainsi qu'une cinquantaine de datations 14C, constituent les fondements d'une étude à vocation pluridisciplinaire sur les relations Homme/milieu en France méditerranéenne.<br /> Aux environs de 50 Ka BP, les vallons du piémont sud du Grand Luberon sont colmatés par de puissants glacis d'accumulation dépassant fréquemment les 30 mètres d'épaisseur et remaniant un abondant matériel torrentiel caillouteux contenant des gélifracts. A leur base, plusieurs « sols rouges » et leur contenu paléontologique, indiquent le caractère plus tempéré des épisodes interstadiaires du Stade Isotopique 3 en domaine méditerranéen.<br />Entre le Dernier Maximum Glaciaire et le Tardiglaciaire (18000-17000 cal BP. ?), période charnière au niveau bioclimatique, une incision majeure intervient, surprenante par son ampleur et sa rapidité. Dès 15500 cal. BP, la tendance morphogénique s'inverse et l'on assiste à une reprise de l'accumulation sédimentaire dans les fonds de vallons. Au sein de cette nouvelle dynamique, de puissantes formations travertineuses se développent aux débouchés d'exsurgences karstiques et signent le réchauffement climatique engagé. Celles-ci constituent jusqu'à présent le plus ancien témoignage du « redémarrage » postglaciaire de la travertinisation dans le sud de la France. Par la suite, et dans l'ensemble des formations détritiques et carbonatées, deux incisions principales se produisent vers 9000 et 6000 cal. BP en alternance avec des phases de remblaiements. Les fluctuations morphogéniques de cette première partie du Postglaciaire s'accordent, et semblent principalement inféodées, aux variations des paramètres bioclimatiques. <br />Dès le Néolithique Final, dans un contexte d'augmentation des occupations humaines, les séquences enregistrent une série de ruptures (incisions) de haute fréquence et de faible amplitude. Ces perturbations sont accompagnées de changements de faciès dans les systèmes carbonatés et d'ouvertures fortes du milieu végétal déterminées par les analyses paléoécologiques. Le caractère particulièrement sensible des ensembles travertineux aux modifications d'origine climato-anthropique du biotope est ainsi souligné. <br />Entre le XIème et le XIIIème siècle après Jésus Christ, on note l'interruption, de l'accumulation des travertins et le démantèlement des formations l.s. (et non entre la fin du Néolithique et la période antique comme il était communément admis). C'est également dans le même intervalle que s'instaure la dynamique majeure d'incision linéaire des talwegs bien connue dans le sud de la France, mais jusqu'à présent rangée dans une chronologie incertaine. Postérieurement au XVIIème siècle, au cours du Petit Age Glaciaire, une dernière période de remblaiement détritique plus modeste débute. A terme, celle-ci est interrompue par une ultime phase d'incision toujours effective aujourd'hui. L'action conjuguée des oscillations climatiques et des modes d'occupation des sociétés humaines sur le milieu « naturel » apparaît comme le principal moteur d'une morphogenèse mouvementée au cours de la deuxième partie du Postglaciaire.

L'évolution des paysages provençaux (sud Luberon, Vaucluse, France) depuis la dernière glaciation est analysée au travers de la dynamique couplée des formations alluviales et des systèmes travertineux, en relation avec les changements climatiques et l'anthropisation. Des analyses géomorphologiques, sedimento-stratigraphiques et physico-chimiques, dont les résultats sont incrémentés par des études archéologiques et paléoécologiques (malacologie et anthracologie) ainsi qu'une cinquantaine de datations 14C, constituent les fondements d'une étude à vocation pluridisciplinaire sur les relations Homme/milieu en France méditerranéenne.<br /> Aux environs de 50 Ka BP, les vallons du piémont sud du Grand Luberon sont colmatés par de puissants glacis d'accumulation dépassant fréquemment les 30 mètres d'épaisseur et remaniant un abondant matériel torrentiel caillouteux contenant des gélifracts. A leur base, plusieurs « sols rouges » et leur contenu paléontologique, indiquent le caractère plus tempéré des épisodes interstadiaires du Stade Isotopique 3 en domaine méditerranéen.<br />Entre le Dernier Maximum Glaciaire et le Tardiglaciaire (18000-17000 cal BP. ?), période charnière au niveau bioclimatique, une incision majeure intervient, surprenante par son ampleur et sa rapidité. Dès 15500 cal. BP, la tendance morphogénique s'inverse et l'on assiste à une reprise de l'accumulation sédimentaire dans les fonds de vallons. Au sein de cette nouvelle dynamique, de puissantes formations travertineuses se développent aux débouchés d'exsurgences karstiques et signent le réchauffement climatique engagé. Celles-ci constituent jusqu'à présent le plus ancien témoignage du « redémarrage » postglaciaire de la travertinisation dans le sud de la France. Par la suite, et dans l'ensemble des formations détritiques et carbonatées, deux incisions principales se produisent vers 9000 et 6000 cal. BP en alternance avec des phases de remblaiements. Les fluctuations morphogéniques de cette première partie du Postglaciaire s'accordent, et semblent principalement inféodées, aux variations des paramètres bioclimatiques. <br />Dès le Néolithique Final, dans un contexte d'augmentation des occupations humaines, les séquences enregistrent une série de ruptures (incisions) de haute fréquence et de faible amplitude. Ces perturbations sont accompagnées de changements de faciès dans les systèmes carbonatés et d'ouvertures fortes du milieu végétal déterminées par les analyses paléoécologiques. Le caractère particulièrement sensible des ensembles travertineux aux modifications d'origine climato-anthropique du biotope est ainsi souligné. <br />Entre le XIème et le XIIIème siècle après Jésus Christ, on note l'interruption, de l'accumulation des travertins et le démantèlement des formations l.s. (et non entre la fin du Néolithique et la période antique comme il était communément admis). C'est également dans le même intervalle que s'instaure la dynamique majeure d'incision linéaire des talwegs bien connue dans le sud de la France, mais jusqu'à présent rangée dans une chronologie incertaine. Postérieurement au XVIIème siècle, au cours du Petit Age Glaciaire, une dernière période de remblaiement détritique plus modeste débute. A terme, celle-ci est interrompue par une ultime phase d'incision toujours effective aujourd'hui. L'action conjuguée des oscillations climatiques et des modes d'occupation des sociétés humaines sur le milieu « naturel » apparaît comme le principal moteur d'une morphogenèse mouvementée au cours de la deuxième partie du Postglaciaire.