L’environnement climatique est l’un des facteurs pouvant influencer la performance aérobie. Il existe des températures idéales avec lesquelles les athlètes réalisent de meilleures performances : entre 10 et 12°C en course à pied (Maughan et coll. 2010) ou inférieures à 32°C en cyclisme (Peiffer & Abbiss 2011). Davies et coll. (2016) condensent dans une métaanalyse différentes études portant sur le contre la montre (CLM) en cyclisme en environnement chaud et relèvent que la performance est altérée en climat chaud à partir du milieu de l’épreuve (P < 0,02) et jusqu’à la fin (P = 0,01) par rapport à une condition contrôle.Ce résultat laisse donc apparaitre qu’outre la température environnementale, la durée de l’effort peut également être déterminante dans l’impact du climat sur la performance. L’élévation de la température n’est pas le seul facteur environnemental pouvant influencer la performance. Maughan et coll. (2012) mettent en évidence qu’au plus le taux d’humidité est élevé au plus la performance aérobie est détériorée. Dans cette étude, des athlètes non acclimatés, réalisent une épreuve à vélo à 70% de VO2max jusqu’à épuisement lors de quatre sessions à 24, 40, 60 et 80% d’HR (T: 30°C). Les résultats, montrent que le temps d’exercice diminue significativement avec l’augmentation du taux d’humidité (P < 0,05).A travers ce travail de recherche nous avons donc investigué la question : comment faire pour limiter cet impact du climat sur la performance ?Pour ce faire 3 axes sont développés à travers nos études :a. Etudier l’efficacité de protocoles de refroidissement à plusieurs moments de la performance : avant, pendant et entre deux efforts consécutif.b. Déterminer si les combinaisons de froid peuvent se combiner.c. Déterminer si l’utilisation du menthol peut permettre une optimisation des protocoles de cooling.Les principaux résultats de cette thèse mettent en évidence que l’utilisation de méthodes de cooling est efficace mais que cette efficacité dépend du protocole utilisé. Nous avons ainsi mis en évidence (1) Qu’en pré-cooling il est nécessaire de débuter 1h avant l’effort pour avoir une efficacité de la méthode ; (2) Qu’une immersion avec du menthol est plus efficace qu’une immersion seule entre deux efforts de 20’ mais qu’utilisé sur des vêtements son efficacité n’est pas prouvée; (3) Que le port d’un gilet froid cumulé à une ingestion d’une boisson froide à l’échauffement n’est pas plus efficace qu’un refroidissement interne seul (4) Que le menthol peut influencer les performances en jouant un rôle sur le SNC.L’action du menthol va permettre au SNC de percevoir l’environnement comme étant « plus favorable » et par conséquent entrainer une modification de la rétroaction thermorégulatrice, et ainsi permettre une meilleure performance. Cela sans que le menthol ne joue un rôle délétère à la thermorégulation. / The climatic environment is one of the factors that can influence the aerobic performance. There are an ideal temperatures with which athletes realize better performance: between 10 and 12°C in running (Maughan et al. 2010) below 32°C in cycling (Peiffer & Abbiss 2011). Davies et al. (2016) condense in a meta-analysis different studies on time trial (TT) in cycling and note that the performance is impaired in hot weather from middle of the test (P <0.02) and until the end (P = 0.01) compared to a condition control. This result therefore shows that in addition to the environmental temperature, the duration of the effort can also be decisive in the impact of climate on the performance.Rising temperature is not the only environmental factor that can influence the performance. Maughan et al. (2012) highlight that at the highest level of humidity is high at most aerobic performance is deteriorated. In this study, non-athletes acclimatized, perform a 70% VO2max bike test until exhaustion four sessions at 24, 40, 60 and 80% RH (T: 30 ° C). The results show that time exercise decreased significantly with increasing humidity (P <0.05). Through this research work we therefore investigated the question: how to do to limit this impact of climate on performance?To do this, 3 axes are developed through our studies: a. Study the effectiveness of cooling protocols at several points in the performance: before, during and between two consecutive efforts.b. Determine if cold combinations can combine.c. To determine if the use of menthol can allow optimization of the protocols of cooling.The main results of this thesis highlight that the use of cooling is effective but this efficiency depends on the protocol used. We havehighlighted (1) That in pre-cooling it is necessary to start 1 hour before the effort to have an efficiency of the method;(2) Immersion with menthol is more effective only a single immersion between two efforts of 20 'but that used on clothes its effectiveness is not proven; (3) That wearing a cold vest combined with ingestion from a cold drink to warm up is no more effective than an internal cooling only (4) That menthol can influence performance by playing a role on the CNS. The action of menthol will allow the CNS to perceive the environment as being "More favorable" and therefore result in a change in the feedback thermoregulatory, allow higher performance. This without the menthol isplayed a deleterious role to thermoregulation.

Waste Stabilisation Ponds (WSPs) are characterised by low phosphorus (P) removal capacity. Heterotrophic bacteria are principal microbial agents in WSPs in addition to algae. As treatment proceeds in WSPs, algal growth increases and pH rises, this has lead to believe that P removal is mainly through sedimentation as organic P algal biomass and precipitation as inorganic P. In activated sludge treatment plants (AS), microbial P removal has been improved and is termed as enhanced biological phosphorus removal. There was a need to establish whether it was possible to enhance P removal in WSPs. A performance assessment of pond system at the University of Dare s Salaam (UDSM), Tanzania, has shown that 90% of the P removed was in the primary pond (facultative) and the rest in the maturation pond (aerobic). In these studies, a pure strain A. hydrophyla was isolated from an activated sludge wastewater treatment plant in Sweden. This plant has a train that functions with enhanced biological phosphorus removal. The strain was tested for P uptake in minimal media supplemented with glucose, succinate or acetate, grown aerobically and anaerobically/aerobically. This strain was able to take up P without having been subjected to the anaerobic phase. It was observed that P uptake was enhanced after the anaerobic phase with media supplemented with glucose, but not with succinate or acetate. Phosphorus uptake repeatedly followed the bacterial growth pattern with correlation coefficients of more than 95%. Therefore P removal has a direct correlation with bacterial growth. Two isolates Acinetobacter sp. (isolated from the primary facultative pond) and E .coli (isolated from the maturation pond) were obtained from a tropical WSP treatment system at the UDSM. They were subjected to aerobic P uptake experiment similar to those of A.hydrophyla. The uptake per unit absorbance of bacterial growth was found to be comparable to that of A.hydrophyla, isolated from AS. These results showed that heterotrophic activity is important in WSPs. It is possible to enhance P removal in these systems by designing the primary ponds for maximum heterotrophic activity and probably enrichment. / QC 20101119

Anthropogenic activities are responsible for the impact of global climate change because of burning fossil fuels releasing harmful gases into the environment. As a result, the global temperature has risen about 1.18 °C since 1880, causing the global sea level to rise by 178 mm over the past century. This is a threat to countries that are closer to the ocean, especially the low-lying countries such as the Maldives. It is predicted if the sea level keeps rising, most of these islands could be below sea level by 2030. The Maldives has a tropical climate requiring cooling to achieve thermal comfort. Electricity is used to provide cooling which is generated by burning fossil fuels. Due to the need for more buildings and the effects of global warming, the demand for cooling has increased, ultimately increasing the emissions. Therefore, this paper investigated the methods to minimize the building cooling demand by creating a building model of a school in Feydhoo, Addu City, Maldives using DesignBuilder software. Also, to analyze the potential of using solar technology in providing cooling for the building, a clean energy source reducing emissions. The base model of the building showed that annual electricity consumption for cooling would be about 200.14 MWh. Based on the base model, multiple building models were created to understand the best option that can lower the cooling demand of the building. The results showed that having a super-insulated timber construction could be a better option by using improved double-glazed low-E windows and an improved cooling system with a COP of 3.2. This lowered the cooling energy demand to about 103.71 MWh. Based on these results, a solar thermal cooling system was simulated using Polysun software which shows that solar thermal collectors were not able to provide the required cooling to run the chiller system. Hence, another option was explored where DesignBuilder software was used to model a solar PV array system to provide cooling for the building. But by using a better air conditioning system (VRF system coupled with a DOAS) to provide fresh conditioned air into the building, improving the indoor air quality. The results showed that the new PV array system was able to provide the electricity required not for cooling but for other electrical requirements (total of 163.31 MWh). It also resulted in a surplus of 1 MWh of electricity exported to the utility grid, achieving a net-positive energy building.

O objeto deste trabalho são os microclimas urbanos nas cidades brasileiras na região de Clima Tropical Continental. Partindo do princípio que há uma correlação entre microclimas urbanos e ocupação do solo, o objetivo é medir numericamente a correlação entre a temperatura do ar e algumas variáveis familiares ao planejamento, e que podem ser regulamentadas pela legislação municipal, a fim de orientar as medidas necessárias para amenizar o rigor climático nas cidades da região. Faz-se uma descrição qualitativa e quantitativa das variáveis urbanísticas envolvidas, bem como medições de temperatura e umidade do ar em diferentes estações e horários. Os resultados mostram que as variáveis taxa de ocupação e coeficiente de aproveitamento mantém correlação positiva com a temperatura do ar, e refletem uma maior influência da densidade construída sobre o período noturno, o que concorda com a teoria existente. Já com as variáveis arborização e água a correlação foi negativa em relação à temperatura do ar, em todos os horários. Ao final propõe-se um índice em função das variáveis urbanísticas utilizadas, visando subsidiar futuros trabalhos na determinação da proporção ideal entre densidade construída, arborização e água. / The subject of this thesis is the urban microclimate in cities of the Brazilian Continental Tropical Region. According to the principle that there is a correlation between urban microclimates and urban occupation, the objective is to numerically measure the correlation between air temperature and variables which are familiar to urban planning strategies. These variables can be controlled by municipal regulations, aiming to guide the procedures to ameliorate the urban harsh climate in that region. Qualitative and quantitative descriptions of the urban variables are made, as air temperature and humidity measurements registered along the day for the two main seasons. The results show that with variables related to building density, the correlation was positive when referred to air temperature, and reflected the greater influence of building density at night, what is in accord with the existing theory. On the other hand, using trees and water, the correlation was negative, when related to air temperature, in all periods. At the end, this work suggests an index using urban variables, aiming to support future studies in determining the ideal proportion among building density, trees and water in urban environments.

Os relatórios científicos relacionados com o período de transição das vacas leiteiras são principalmente realizados com animais de raças europeias e em climas temperados. Países com clima tropical estão ganhando importância como fornecedores de alimentos para o mundo e o estudo de raças adaptadas e integradas nessas regiões pode contribuir para o desenvolvimento de práticas de manejo alimentar que melhorem a eficiência bioeconômica dos sistemas de produção. Vinte e quatro animais da raça Holandesa (H) e Girolando F1 - ½ Holandês Gir (F1) foram utilizados durante o período pré-parto (12 H e 12 F1) e 16 animais no período pós-parto (8 H e 8 F1). Os animais foram alimentados com ração totalmente misturada, seguindo dois planos nutricionais antes do parto, com ofertas de 1,69 e 1,89% do peso vivo, com base na matéria seca. Após o parto, os animais foram alimentados ad libitum. Testes de digestibilidade aparente e avaliações em câmaras respirométricas foram realizados 21 dias antes do parto previsto e 21 dias após o parto. Utilizou-se delineamento inteiramente casualizado e os dados foram analisados por ANOVA e a comparação das médias entre os grupos foi realizada pelo teste de Tukey, com nível de significância de 5%. No período pré parto, houve algumas diferenças entre as composições raciais, com maior escore de condição corporal para os animais F1, sem diferença no consumo de matéria seca. Os animais submetidos ao plano 1,89 % apresentaram maior digestibilidade da matéria seca. A emissão e o rendimento do metano entérico foram semelhantes entre as duas composições raciais. Durante o período pós parto, os animais H apresentaram maior consumo de todos os nutrientes, com maior produção de leite e maior emissão de metano por unidade de peso corporal e peso metabólico. Não houve diferença na emissão de metano entérico por quilograma de leite ou leite corrigido para gordura entre composições raciais e planos nutricionais. A partição energética de ambas as composições foi similar, mas o maior escore de condição corporal, menor produção de leite e emissão de metano entérica total semelhante sugerem que os animais Girolando F1 criados em condições tropicais são menos eficientes energeticamente quando submetidos a planos nutricionais recomendados para manutenção de raças europeias. / Scientific reports related to the transition period of dairy cows are mainly carried out with animals of European breeds and in temperate climates. Countries with a tropical climate are gaining importance as suppliers of food to the world and the study of breeds adapted and integrated in these regions can contribute to the development of food management practices that improve the bioeconomic efficiency of production systems. Twenty-four animals of Holstein (H) and Girolando F1 – ½ Holstein ½ Gir (F1) breed composition were used during the prepartum period (12 H and 12 F1), and 16 animals during the postpartum period (8 H and 8 F1). The animals were fed a total mixed ration, following two nutritional plans before calving, with offers of 1.69 and 1.89% of body weight, on a dry matter basis. After calving, the animals were fed ad libitum. Apparent digestibility assays and evaluations in respirometric chambers were performed 21 days before the expected calving and 21 days after calving. A completely randomized design was used and the data were analyzed by ANOVA and the comparison of the means between the groups was done by the Tukey’s test, with significance level of 5 %. In the prepartum period, there were some differences between the breed composition, with a higher body condition score for F1 animals, with no difference in the dry matter intake. The animals subjected to the 1.89% plan presented higher digestibility of dry matter. The emission and yield of enteric methane was similar between both racial compositions. During the postpartum period, H animals presented higher intake of all nutrients, with higher milk production, and higher methane emission per unit of body weight and metabolic weight. There was no difference in the emission of enteric methane per kilogram of milk or fat corrected milk between breed compositions and nutritional plans. The energy partition of both compositions was similar, but the higher body condition score, lower milk yield, and similar total enteric methane emission suggest that Girolando F1 animals raised under tropical conditions are less energy efficient when subjected to nutritional plans recommended for the maintenance level of European breeds.

Os relatórios científicos relacionados com o período de transição das vacas leiteiras são principalmente realizados com animais de raças europeias e em climas temperados. Países com clima tropical estão ganhando importância como fornecedores de alimentos para o mundo e o estudo de raças adaptadas e integradas nessas regiões pode contribuir para o desenvolvimento de práticas de manejo alimentar que melhorem a eficiência bioeconômica dos sistemas de produção. Vinte e quatro animais da raça Holandesa (H) e Girolando F1 - ½ Holandês Gir (F1) foram utilizados durante o período pré-parto (12 H e 12 F1) e 16 animais no período pós-parto (8 H e 8 F1). Os animais foram alimentados com ração totalmente misturada, seguindo dois planos nutricionais antes do parto, com ofertas de 1,69 e 1,89% do peso vivo, com base na matéria seca. Após o parto, os animais foram alimentados ad libitum. Testes de digestibilidade aparente e avaliações em câmaras respirométricas foram realizados 21 dias antes do parto previsto e 21 dias após o parto. Utilizou-se delineamento inteiramente casualizado e os dados foram analisados por ANOVA e a comparação das médias entre os grupos foi realizada pelo teste de Tukey, com nível de significância de 5%. No período pré parto, houve algumas diferenças entre as composições raciais, com maior escore de condição corporal para os animais F1, sem diferença no consumo de matéria seca. Os animais submetidos ao plano 1,89 % apresentaram maior digestibilidade da matéria seca. A emissão e o rendimento do metano entérico foram semelhantes entre as duas composições raciais. Durante o período pós parto, os animais H apresentaram maior consumo de todos os nutrientes, com maior produção de leite e maior emissão de metano por unidade de peso corporal e peso metabólico. Não houve diferença na emissão de metano entérico por quilograma de leite ou leite corrigido para gordura entre composições raciais e planos nutricionais. A partição energética de ambas as composições foi similar, mas o maior escore de condição corporal, menor produção de leite e emissão de metano entérica total semelhante sugerem que os animais Girolando F1 criados em condições tropicais são menos eficientes energeticamente quando submetidos a planos nutricionais recomendados para manutenção de raças europeias. / Scientific reports related to the transition period of dairy cows are mainly carried out with animals of European breeds and in temperate climates. Countries with a tropical climate are gaining importance as suppliers of food to the world and the study of breeds adapted and integrated in these regions can contribute to the development of food management practices that improve the bioeconomic efficiency of production systems. Twenty-four animals of Holstein (H) and Girolando F1 – ½ Holstein ½ Gir (F1) breed composition were used during the prepartum period (12 H and 12 F1), and 16 animals during the postpartum period (8 H and 8 F1). The animals were fed a total mixed ration, following two nutritional plans before calving, with offers of 1.69 and 1.89% of body weight, on a dry matter basis. After calving, the animals were fed ad libitum. Apparent digestibility assays and evaluations in respirometric chambers were performed 21 days before the expected calving and 21 days after calving. A completely randomized design was used and the data were analyzed by ANOVA and the comparison of the means between the groups was done by the Tukey’s test, with significance level of 5 %. In the prepartum period, there were some differences between the breed composition, with a higher body condition score for F1 animals, with no difference in the dry matter intake. The animals subjected to the 1.89% plan presented higher digestibility of dry matter. The emission and yield of enteric methane was similar between both racial compositions. During the postpartum period, H animals presented higher intake of all nutrients, with higher milk production, and higher methane emission per unit of body weight and metabolic weight. There was no difference in the emission of enteric methane per kilogram of milk or fat corrected milk between breed compositions and nutritional plans. The energy partition of both compositions was similar, but the higher body condition score, lower milk yield, and similar total enteric methane emission suggest that Girolando F1 animals raised under tropical conditions are less energy efficient when subjected to nutritional plans recommended for the maintenance level of European breeds.

Cette thèse s'inscrit dans le cadre du programme international AMMA (Analyse Multidisciplinaire de la Mousson Africaine) dont un des objectifs est de mieux connaître les dynamiques régionales des interactions climat-environnement-société. Elle est une contribution à l'étude de la variabilité spatio-temporelle de la végétation, en fonction des différents types d'occupation du sol et sous contrainte des variations saisonnières et interannuelles de la pluviométrie sur la partie supérieure du bassin versant du fleuve Ouémé, au Bénin. Cette espace possède un important réseau de surveillance hydroclimatique au sol, l'observatoire AMMA-Catch, qui fournit de nombreuses données in situ. L'analyse s'appuie aussi sur différentes données issues de la télédétection satellitaire optique (LANDSAT, SPOT-VGT, MODIS, MSG-SEVIRI ou ECOCLIMAP) pour l'étude de l'occupation du sol, de la variabilité photosynthétique de la végétation ou des estimations pluviométriques (RFE – Rainfall Estimate). L'étude porte principalement sur trois questions : 1) les modifications des états de surface récemment observées dans cette zone expérimentale de l'Ouémé supérieur ; 2) la valorisation des différentes données issues de la télédétection satellitaire pour diagnostiquer la variabilité bioclimatique régionale de la végétation ; 3) la compréhension des interactions à l'interface climat/végétation, pour interpréter certaines variations bioclimatiques intra- et interannuelles en fonction des principaux états de surface. Les principaux résultats suggèrent qu'il est possible de discriminer des relations fonctionnelles selon les principaux états de surface forestiers ou très anthropisés. Les analyses diachroniques par classification d'images Landsat (ETM+) montrent que les espaces cultivés enregistrent régionalement une augmentation de 25 % sur la période 2003-2012. Les superficies de jachère diminuent, alors que les savanes arbustives augmentent. Tous les espaces forestiers perdent en superficie sur la décennie observée, en particulier les forêts denses (a priori protégées dans cette région) avec une baisse supérieure à 16 %. La variabilité spatio-temporelle d'un indice de végétation (NDVI) est significativement dépendante des trois principaux modes d'occupation du sol, même si l'artefact dû à la nébulosité complique les analyses et interprétations. Les contrastes entre le domaine de forêt naturelle encore préservée (la forêt classée) et les espaces en mutation agricole (cultures et jachères) sont particulièrement visibles. Sur la décennie 2002-2012, il n'y a pas de tendance des pluies, mais plutôt une succession de phases sèches et humides, qui induisent finalement une stabilité interannuelle du NDVI. Le déphasage moyen entre pluies et activité végétale est en moyenne de quatre décades, mais il semble que la fin de la saison végétative recule ait reculé d'au moins 10 jours sur la période étudiée, traduisant une modification des précipitations de fin d'année. / This thesis is part of the international AMMA program (Analyse Multidisciplinaire de la Mousson Africaine - Multidisciplinary Analysis of African Monsoon) whose objective is to better understand the regional dynamics of climate-environment-society interactions. It is a contribution to the study of the spatio-temporal variability of vegetation, according to different land use types and under the constraints of seasonal and interannual variations in rainfall in the upper basin of Ouémé river, Benin. This area has an extensive network of hydro-climatic ground monitoring, observatory AMMA-Catch, which provides many in-situ data. The analysis also relies on data from different optical remote sensing satellites (LANDSAT, SPOT-VGT, MODIS, MSG-SEVIRI or ECOCLIMAP) for the study of land occupation, variability of photosynthetic vegetation or rainfall estimate (RFE). The study focuses mainly on three questions: 1) the changes in surface conditions recently observed in the experimental area of upper Ouémé; 2) the analysis of various data from satellite remote sensing to diagnose regional bioclimatic variability of vegetation; 3) the understanding of climate/vegetation interface interactions, in order to interpret certain intra-and interannual bioclimatic variations depending on the main surface conditions. The main results suggest that it is possible to discriminate the functional relationships from the main conditions of forest or anthropized surface. The diachronic analysis through the classification of Landsat (ETM +) images show that the cultivated areas recorded regionally an increase of 25% over the period of 2003-2012. The areas of set-aside decrease, while shrublands increase. All forests lost in area over the decade observed, particularly dense forest (presumably protected in this region) with a drop of over 16%. The spatio-temporal variability of a vegetation index (NDVI) significantly depends on three main types of land use, even though the noise due to the cloud cover complicates the analysis and interpretation. The contrasts between the preserved natural forest area (the forest reserve) and the agricultural areas (crops and fallow) are particularly visible. Over the decade 2002-2012, there is no trend of rainfall, but rather a succession of wet and dry phases, which ultimately induce an interannual stability of NDVI. The average phase difference between rainfall and vegetation activity is four decades, but it seems that the end of the vegetation growing season has retreated back to at least 10 days during the study period, reflecting a change in rainfall at the end of the year.

O objeto deste trabalho são os microclimas urbanos nas cidades brasileiras na região de Clima Tropical Continental. Partindo do princípio que há uma correlação entre microclimas urbanos e ocupação do solo, o objetivo é medir numericamente a correlação entre a temperatura do ar e algumas variáveis familiares ao planejamento, e que podem ser regulamentadas pela legislação municipal, a fim de orientar as medidas necessárias para amenizar o rigor climático nas cidades da região. Faz-se uma descrição qualitativa e quantitativa das variáveis urbanísticas envolvidas, bem como medições de temperatura e umidade do ar em diferentes estações e horários. Os resultados mostram que as variáveis taxa de ocupação e coeficiente de aproveitamento mantém correlação positiva com a temperatura do ar, e refletem uma maior influência da densidade construída sobre o período noturno, o que concorda com a teoria existente. Já com as variáveis arborização e água a correlação foi negativa em relação à temperatura do ar, em todos os horários. Ao final propõe-se um índice em função das variáveis urbanísticas utilizadas, visando subsidiar futuros trabalhos na determinação da proporção ideal entre densidade construída, arborização e água. / The subject of this thesis is the urban microclimate in cities of the Brazilian Continental Tropical Region. According to the principle that there is a correlation between urban microclimates and urban occupation, the objective is to numerically measure the correlation between air temperature and variables which are familiar to urban planning strategies. These variables can be controlled by municipal regulations, aiming to guide the procedures to ameliorate the urban harsh climate in that region. Qualitative and quantitative descriptions of the urban variables are made, as air temperature and humidity measurements registered along the day for the two main seasons. The results show that with variables related to building density, the correlation was positive when referred to air temperature, and reflected the greater influence of building density at night, what is in accord with the existing theory. On the other hand, using trees and water, the correlation was negative, when related to air temperature, in all periods. At the end, this work suggests an index using urban variables, aiming to support future studies in determining the ideal proportion among building density, trees and water in urban environments.

Les eaux souterraines constituent un des principaux facteurs de contrôle influençant l'activité des glissements de terrain. L'étude hydrogéologique constitue donc une étape incontournable dans la compréhension de leur fonctionnement, en vue de prédire leur déplacement ou d'adapter les solutions d'assainissement. Cependant, les aquifères qui se développent au sein des glissements de terrain sont généralement complexes, et la compréhension de l'hydrogéologie des grands glissements reste encore aujourd'hui une problématique majeure. Dans un contexte climatique extrême de type tropical humide, les glissements du cirque de Salazie (île de La Réunion) constituent des cas d'étude particulièrement porteurs pour l'apport de nouvelles connaissances sur l'hydrogéologie et le fonctionnement des mouvements de terrain de grande ampleur. Pour caractériser ces glissements, une étude pluridisciplinaire associant géologie, hydrochimie, modélisation numérique (globale et déterministe), est mise en œuvre. Sur le secteur nord du cirque de Salazie, l'étude géologique réalisée permet de reconstruire la géométrie de la base d'une instabilité de très grande ampleur, dont le volume est estimé à 370 Mm3. Le glissement de Grand Ilet (175 Mm3) en est la partie la plus active. Les formations volcano-détritiques (brèches) constituant le glissement sont des dépôts d'une ancienne avalanche de débris (> 350 Ma), réactivés localement. Cette étude met également en évidence un régime de déformation extensif associée à l'activité du glissement, favorisant le développement de zones décomprimées subverticales. Au sein des brèches constituant la zone instable, un aquifère continu est identifié. Les écoulements souterrains y sont contrôlés par la géométrie de la base du glissement. Par ailleurs, la nature du couvert végétal en surface, le climat, les propriétés des sols et l'épaisseur de la zone non saturée font que seuls les épisodes pluvieux intenses dont le cumul dépasse 80 mm/ évènement génèrent une recharge de l'aquifère des brèches. Lors de cette recharge, les zones décomprimées favorisent des transferts rapides (< 1 jour) à travers la zone non-saturée, malgré des épaisseurs pouvant atteindre localement 160 mètres. Une infiltration plus lente percole à travers la matrice poreuse des brèches. Pour l'étude de la dynamique des grands glissements dans le cirque de Salazie, l'application de l'outil de modélisation inverse met en évidence que les variations de vitesses de déplacement sont directement reliée aux processus de recharge et de tarissement de la nappe des brèches. Ces modèles s'avèrent particulièrement performants pour prédire les déplacements des grands glissements et comprendre leur fonctionnement. / The landslide activity is commonly controlled by the variation of hydraulic head inside the instable mass. Thus, the hydrogeological study of landslides is an essential step to predict landslide dynamic, and for the remediation choices. However, the aquifers developed in landslide are generally complexes. Actually, the comprehension of landslide hydrogeological functioning is a major problematic, especially for the deep-seated landslides.Under humid tropical climate, the Salazie landslides (Reunion Island) allow to implement an interesting study to characterized deep-seated landslide hydrogeology and functioning. In this study, we performed a multidisciplinary approach, combining geology, hydrochemistry and numerical modeling (global and deterministic);The geological study allows the construction of the deep seated landslide geological model (Grand Ilet sector). The Grand Ilet landslide, corresponding to 175 Mm3, is the most active part of deep seated instability whose the total volume is estimated at 370 Mm3. The volcano-detritic lithologies (i.e basic breccia) constitute the main geological formation of the unstable mass. This breccia is a present-day reactivation of an old destabilization (> 350 Ma). Furthermore, the extensive deformation generated by the landslide activity allows the formation of decompressed zones.Inside breccias, a continuous aquifer is identified. Here, the groundwater flows are controlled by the geometry of the landslide base. Natural land cover, soils properties, unsaturated zone thickness and warm temperature limit the groundwater recharge. Only the intense rainfall episode (80 mm/event) can generated the recharge of landslide aquifer. During these events, rapid transfers circulating inside the decompressed zones have a significant effect on hydraulic charge variations. A slow component is infiltrated inside the porous medium of breccias.The inverse modeling methods with bimodal Gaussian-Exponential transfer function is applied to study the Salazie landslides dynamic. The results show that landslide speed variations are directly controlled by groundwater level variations during the hydrologic cycle (recharge and recession stage). Consequently, the inverse model is a powerful tool for predicting deep-seated landslide movements and for studying how they function.

Les eaux continentales sont des sources de méthane (CH4), de dioxyde de carbone (CO2)et de protoxyde d’azote (N2O). Dans le but de préciser leur importance dans le bilan global des émissions de gaz à effet de serre (GES), de nombreuses études ont été réalisées afin de quantifier les différents flux de carbone et d’azote les parcourant. Ces flux sont perturbés par la mise en place de barrages sur le lit des fleuves. Peu d’études présentent des bilans de carbone et d’azote complets (apports, exports, flux vers l’atmosphère et enfouissement) pour les lacs de barrages, et elles concernent uniquement des écosystèmes boréaux et tempérés. Suite à la création d’un barrage, de la matière organique (MO) est mise en eau (sols et forêts), elle se dégrade rapidement les premières années suivant la mise en eau puis plus lentement par la suite. L’état de dégradation de la MO et la principale source de GES dans un lac de barrage près de 20 ans après la mise en eau sont souvent méconnus. L’étude réalisée 18 ans après la mise en eau du lac de Petit Saut (Guyane Française) est la première étude où les principaux éléments des cycles du carbone et de l’azote d’un lac de barrage hydroélectrique, et de son fleuve en aval, situé en climat équatorial et dont la création a entraîné la mise en eau de forêt primaire, sont étudiés près de 20 ans après la mise en eau. Cette étude se base sur (i) la mesure mensuelle de la qualité des eaux et des concentrations en carbone et azote en amont, dans, et en aval du lac de barrage, (ii) la mesure et/ou le calcul des différents flux de GES vers l’atmosphère, (iii) des données de la signature isotopique et de l’état de dégradation de la MO en amont, dans, et en aval du lac, (iv) des prélèvements de sédiments et de troncs d’arbres ennoyés en 1994 et (v) des incubations d’eau du fleuve, de sédiments et de troncs d’arbres du lac. L’ensemble des données collectées au cours des 12 mois de campagnes réalisées en 2012 - 2013 nous a permis de déterminer que (i) les sols inondés sont toujours des sources significatives de GES contrairement aux troncs d’arbres ennoyés, (ii) dans le lac 84 % des émissions de CH4 et 51 % des émissions de CO2 ont lieu dans la zone littorale (< 10 m de profondeur), (iii) 54 % du CO2 produit dans le fleuve en aval provient de la dégradation de la MO apportée par le lac. Cette étude nous a aussi permis de réaliser des bilans de carbone et d’azote à Petit Saut et un bilan des émissions de chacun des GES émis (CH4, CO2, N2O) près de 20 ans après la mise en eau. / Inland waters are sources of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). In order to define their importance in the global balance of greenhouse gases (GHG) emissions, numerous studies have been conducted to quantify the different fluxes of the carbon and nitrogen browsing them. These fluxes are modified by the creation of dams on river beds. Few studies present full carbon and nitrogen balances (inputs, outputs, fluxes to the atmosphere and sequestration) for reservoirs, and they concern only boreal and temperate ecosystems. The creation of a dam floods organic matter (OM) (soils and forests), which is rapidly degraded the first years following the impoundment and thereafter more slowly. The state of degradation of the OM and the main source of GHG in a reservoir nearly 20 years after impoundment are often unknown. The study conducted 18 years after the impoundment of the Petit Saut Reservoir (French Guiana) is the first study where the main elements of carbon and nitrogen cycles of an hydroelectric reservoir, and its river downstream, located in equatorial climate and which creation resulted in the flooding of primary forest, are studied nearly 20 years after impoundment. This study is based on (i) a monthly measurement of water quality and carbon and nitrogen concentrations upstream, in, and downstream of the reservoir, (ii) measurements and/or calculations of the different fluxes of GHG through the atmosphere, (iii) data of the isotopic signature and of the state of degradation of OM upstream, in, and downstream of the reservoir, (iv) sediments and 1994’s flooded tree trunks sampling and (v) incubations of downstream river water, sediments and tree trunks from the reservoir. All the data collected during the 12 months of campaigns carried out in 2012 - 2013 allowed us to determine that (i) flooded soils are still significant sources of GHG unlike flooded tree trunks, (ii) in the reservoir 84 % of CH4 emissions and 51 % of CO2 emissions occur in the littoral zone (< 10 m depth), (iii) 54 % of the CO2 produced in the river downstream of the dam come from the degradation of the OM provided by the reservoir. This study also allowed us to achieve carbon and nitrogen balances in Petit Saut and emission balance of each GHG emitted (CH4, CO2, N2O) nearly 20 years after impoundment.