Dissertations / Theses on the topic 'Climat – Sénégal'
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Ndiaye, Aminata. "Les paramètres de l'environnement et la pluviogenèse à travers un système d'information géographique : application à l'hivernage 1990 au Sénégal." Paris 1, 1994. http://www.theses.fr/1994PA010702.
Full textThe experience acquired over several years in the field of rainfall estimation in the Sahelian zone by satellite, has shown that on the regional scale, the results were globally satisfactory. However, on a local scale, it is necessary to take physical and climatic specificities of the study zone in account, by introducing complementary parameters in the computation of the relationships which describe the quantity and the areal distribution of rainfall. This is the method which has been used in Senegal, in the coastal countries of West Africa, where the research for appropriate indicators has been conducted within a geographical information system (GIS), in order to adapt existing models to local conditions
Sarr, Mamadou Adama. "Évolution récente du climat et de la végétation au Sénégal : cas du Bassin versant du Ferlo." Lyon 3, 2009. http://www.theses.fr/2009LYO31058.
Full textUnderstand the evolution and the recent variability of the climate in the arid and semi-arid regions is a necessity in order to anticipate what could be the consequences on the environments and on the societies of those regions, and thus define the strategic politics of sustainable development. To reach that goal, we have organised our research in three parts. The first part treats of the geographical plan through a detailed description of the physical environment and of the different systems of the ground occupation. This description put in evidence a fragile ecosystem under high pressure due to the activities which are employed here. The description summarizes also the middle climate frame by accentuating on the general mechanisms of the general circulation of West Africa which is part of the study zone. The analysis constitutes a recall of the dynamic average global conditions of the climatic tropical field which, in relation with local and regional factors, determines the average components of time in the study field and its margins. The second part concerns the analysis of the spatiotemporal variability on the period going from 1951 until 2005 by putting the accent more on the recorded rainfall than on other climatic parameters such as temperature, evaporation, relative humidity and insulation. But it underlines first the physical and methodological constraints which are compulsory for the statistic analysis of the parameters and justify also the models retained for the use of the database. The analysis of the recorded rainfall results show a high variability, but also a quasi stationarity from the end of the years 1970 and that until the middle of the 1980’s, and since an increase of the annual precipitation volumes on the totality of the study field. Compared to the evolution of other parameters (insulation, temperatures, evaporation and relative humidity), the middle of the 1980’s and the beginning of the years 1990’s appear like a period of trend “break up” justifying the questioning on the persistence or not of the dry trend of the Sahel climate in its totality. The third part starts by the analysis of the evolution of the vegetal production different time scale on the basis of a serie of synthesis images NDVI (Normalized Differential Vegetation Index) of NOAA-AVHRR on the period going from 1981 until 2005. The evaluation of the inter-annual and intra-annual evolution of the vegetal production in relation with the precipitations in the study field demonstrates a good correlation. On the other hand, the anthropic actions, within the framework of execution of the politics of planning disturb this close relation. This situation is put in evidence by the results obtained in the analysis of the cartography of the ground occupation changes between 1990 and 2002. The study conceived on the treatment of the images TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) of Landsat in support of the statements of grounds; confirms the human action in the expansion from the bush savannah to arborous. After defining the characteristics, the follow up tool of the vegetation of the sensor SEVIRI of the satellite MSG is proposed. The corroboration of this new product is done on the basis of a comparative study with those of SPOT-VEGETATION and NOAA-AVHRR, frequently used in the scientific field. After a recall of the essential results of the research, the general conclusion insists on the exploration of solutions for water problems, important for a performing agriculture and a reduced mobility of the pastoral activity. And that passes through the multiplication of studies on the climatic variability, mostly on local scale. The general conclusion shows also the necessity of an approach of multi-sensors for the vegetation follow up. Finally, in order to bring more precisions for the comprehension of the thesis, you will find in the appendix elements concerning the characteristics of satellites as well as the sensors used and a study of cross validation on the techniques of spatial interpolation
Sarr, Benoît. "Climat et agriculture en Afrique Tropicale : le cas de la riziculture dans les espaces aménagés du bassin du fleuve Sénégal." Dijon, 1995. http://www.theses.fr/1995DIJOL013.
Full textThe basin of the Senegal river has been recently the subject of hydro-agricultural equipment (like the dam of Diama and the dam of Manantali). These equipment have been conceived, in order to promote the irrigate cultures of diversification mainly, especially the rice irrigated culture. However, the functioning of the different hydro-agricultural systems is conditioned by mainly constraints of the social, sanitary, and natural environment, including the climate. Among the climatic constraints we find according to the stations and the seasons: diurnal strong heat and by cold nights, worm and dry winds, and important losses in water because of the evapotranspiration, rainfall, etc. The agroclimatical challenges have been studied, mostly the problems of the choice and settlement of the cycles of the irrigated culture. The frequantial analysis of the data and or the numeric simulation have made it possible to detect on one hand the climatic optimal dates for the cultures and on the other hand the rice varieties which genetic properties are tolerant of not with the atmospheric stresses. The whole results have allowed to distinguish two types of gradients: an e-w gradient which brings differences between littoral stations, semi-continental stations and continental stations then a n-s gradient which opposes the sites of the Sahel and its peripheries
Sakho, Issa. "Evolution et fonctionnement hydro-sédimentaire de la lagune de la Somone, Petite Côte, Sénégal." Rouen, 2011. http://www.theses.fr/2011ROUES036.
Full textLocated at the Petite Côte of Senegal, Somone is a small coastal river that flows into the Atlantic Ocean by a microtidal lagoonal-estuarine ecosystem. Today, the contribution of the watershed is absent due to a combination of several factors including the dam of Bandia. The only freshwater inputs are from precipitation and groundwater. Somone is a lagoonal-estuarine system characterized by an inverse hydrological functioning where marine influences predominate. Mangrove, dominated by Rhizophora, is the main characteristic unit of this coastal system. The diachronic evolution of 60 years shows a significant change for all the morphological units of the ecosystem. The mobility of the sandy spit, which caused the closures of the mouth in 1967-1969 and in 1987, is related to meteorological variations. The regressive surface of mangroves between 1954 and 1989 is the result of the combined effect of these closures of the mouth, drought and traditional uses of mangroves. The restoration of the mangrove is mainly due to reforestation policies administered in the 2000s. The annual and seasonal trend shows that the internal reworking is the main hydro-sedimentary processes. Sedimentation rate of the mud flats is 2 to 3 mm. Year-1. The dynamics of the sandy spit of the Somone plays an important role in the development and quality of internal units, the mangroves in particular. The permanent opening of the mouth allows a twice-daily renewal of water in the lagoon, which is essential for regulating the high salt content. The low content of sediment in total organic carbon, reflect the low organic matter production of the mangrove because it is a young and stunted mangrove. Diagenetic processes are anaerobic and mostly in the top 10 cm of the sediment, on the recent deposit. The contribution of young mangroves, like Somone, in the carbon storage process, is low. The lagoonal-estuarine ecosystem of the Somone is fragile and highly reactive and his evolution is fast and linked to the cumulative effects of natural and anthropogenic factors
Noblet, Mélinda. "L'adaptation au changement climatique en zone côtière au Canada et au Sénégal, une comparaison Nord-Sud." Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0042/document.
Full textThis thesis addresses the institutional and vernacular processes of adaptation to climate change in coastal areas. The purpose of this study is to challenge the generally accepted idea by the international community that the southern countries would be more vulnerable and able to cope with the negative impacts of the CC than the northern countries. Canada, a northern country considered developed and the Senegal a southern country perceived under development were selected as case studies. This thesis analyses the ways the problems of the climate and climatic vulnerability are perceived and managed by the Canadian and Senegalese societies and critically examines the actions taken at the title of adaptation. We chose to proceed within a constructivist perspective by establishing the framework of the analysis which concurrently combines the approaches multi-scalar, definitional, interactive and diachronic. From a methodological point of view, this thesis is based on a qualitative approach and privileges semi-directed interview and focus group. The results show that the climatic vulnerability is an international problem and the capacities to be adapted are equally weak in both countries. We have also observed that global warming and the problems it produces put under serious questions the methods of managing environmental issues and patterns of development in both sides north and south
Top, Arame. "Évolution des systèmes de production agricole dans un contexte de changement climatique et de migration et effet de genre dans les trois zones éco-géographiques de la région de Matam au Sénégal." Thesis, Toulouse 2, 2014. http://www.theses.fr/2014TOU20030/document.
Full textThe development of production systems in a global context and such kind of effect in the Matam region aims to introduce mutations in a traditional development environment based on crop rotation and seasonal and spatial alternation in context of irrigated agriculture through the waters of the Senegal River. This context is part of a state policy Senegalese anxious to boost household food security of the river valley rocked by a violent climate crisis which hit nearly two decades. These populations heavily dependent decline integrated culture in a traditional production system that highlighted the livestock, fisheries, rainfed agriculture, seasonal migration, saw their hopes dashed survival. Commissioning of dam Diaman and Manantali, registered in the 0MVS program (development of the Senegal River) between riparian countries (Senegal, Mauritania, Guinea and Mali) significantly reduced the occurrence of floods. This program, which had vast ambitions confiscated the life of riverine populations of the river hindsight flood the Senegal River. These people, whose seasonal migration was part of their production system, adopted a long-term migration to ensure food security of households left the village. The irrigated farming system implemented through irrigation schemes, requires greater human resources and flood recession cultivation and higher production costs
Diouf, Aliou. "Interactions société, nature et climat au Sahel : la rupture socio-économique et écologique au Centre-Est agro-sylvopastoral sénégalais au XXe siècle." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25853/25853.pdf.
Full textSall, Moussa. "Crue et élévation du niveau marin à Saint-Louis du Sénégal : impacts potentiels et mesures d'adaptation." Le Mans, 2006. http://cyberdoc.univ-lemans.fr/theses/2006/2006LEMA3003.pdf.
Full textSenegal river delta is a low area under Atlantic Ocean and Senegal river influences. During the rainy season, the annual river flow, depending to the rainfall in the upper watershed, is combinated to the seasonal sea level rise due to the tropical water flow and the monsoon which accumulate water on the coast. From now to 2 100, sea level will increase because of global temperature rise linked to climate change. Human interventions, like dikes, protect the delta's low areas from flood. Nevertheless, the Diama's dam can't protect Saint-Louis town again flood. Then emergency level has a probability of 34% to occur by year in Saint-Louis and will happen every three years. But water level does not explain all. The duration of water stagnation or the slow evacuation of flow is important too. Then, no dredges, lengthening of "Langue de Barbarie" and sea level rise have increased this phenomenon. Different scenarios of water level based on Senegal river flows at Saint-Louis and sea level rise forecast, carry away impacts with various intensities in Saint-Louis town
Sakho, Issa. "Évolution et fonctionnement hydro-sédimentaire de la lagune de la Somone, Petite Côte, Sénégal." Phd thesis, Université de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00680519.
Full textMbaye, Ibrahima. "Climat et société dans l'apparition et la diffusion de la méningite à méningocoque en zone Soudano-Sahélienne de l'Afrique de l'ouest : Le cas du site de Niakhar (Sénégal)." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. http://www.theses.fr/2005STR1GE16.
Full textCoulibaly, Mamadou Lamine. "Victimations, climat et institutions scolaires : essai de reconstruction du concept de violences scolaires comme objet d’étude à partir d’une comparaison Sénégal-France." Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21801/document.
Full textThis thesis is driven by two goals. The first one deals with assessing school victimizations/bullying in Senegal using a survey answered by 2707 pupils from middle grade (junior high school in France) and secondary grade (Senior high). Its other goal was to focus on seeking for global explanations as well as sociological and historical grounds for “school victimizations” through a comparison with the studies and unchallenged works carried out in France since the 2000s.Based on a study about the connections between deviancy, juvenile delinquency and school, we’ve found that the influence of external factors driving to school violence phenomena is all relative, even diminished, compared to purely institutional – so internal- factors. This confrontation and comparison bring out a paradox: Firstly, Senegalese pupils are relatively protected from schoolmates’ acts of violence. Secondly, in France, micro-acts of violence aimed at teachers tend to develop increasingly. This can be explained by the specific organization and working of each school system.Thus, school violence in Senegal is shaped by educational relations which are based on cultural representations that justify rather coercive teaching methods. It is obviously reflected in the punitive power of the teacher as well as the superiority of school staff due to their age and their sex. Consequently those facts establish relations of power. The situation in France lies on contradictions between institutional policies –school offers- and social demands in education. The first are linked to paradoxical orders such as, on the one hand, compulsory school attendance and academic success and, on the other hand, ranking and selective assessment which totally neglect the pupils’ cognitive skills. Consequently the latter are left with nothing but survival strategies aiming at “saving face” which implies all kinds of transgressions, incidents and disturbing of order within the class
Sané, Tidiane. "Vulnérabilité et adaptabilité des systèmes agraires à la variabilité climatique et aux changements sociaux en Basse-Casamance (Sud-Ouest du Sénégal)." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC155/document.
Full textThe purpose of this research is to analyze vulnerability and adaptability of agrarian systems face to climate variability and social changes in Basse-Casamance, a region where rice growing is a multi-decade. The study focuses on an important aspect of rural development in a context of armed conflict and raises the issue of the dynamics of these systems, which have become an environmental, socio-cultural, economic and political issue. It emphasizes the relationship between the Diola peasant and his environment, through a remarkably ingenious agricultural management, which structuring reflects the deep appropriation of land and embodies a fundamental socio-spatial dimension of the "identity" of the region. Issued from a long social and societal history, from the ingenuity of techniques associated with the exploitation of the environment and the diversity of agrarian systems, rice growing in Basse-Casamance has been facing for more than forty years, multiple external forces, with decisive environmental and socio-economic consequences. The strong climatic variability (rainfall in particular), a key aspect in tropical environment, seems to be one of the triggers of the past and current environmental transformations observed in the region. It has led to other extreme events, with complex contours (high salinity of water and soil, soil acidity, siltation, etc.), therefore, rice growing in many plots of the region has become unpracticable. The magnitude of the changes is measured by a global and multi-scale approach in geography, which integrates both geomatics’ tools (Remote Sensing, GIS, statements of GPS points) and fieldwork (water and soil sampling, physico-chemical analyzes, direct observations, household surveys and people perceptions). This approach led to an important mapping of the observations from diachronic levels and revealed the major trends of the mutations over whole Basse-Casamance and on the scale of rice growing areas. The historical approach has led to a better understanding of the basis of this rice-growing and the conditions under which it is developing. This paradigm is greatly influenced by the public policies in terms of rice growing, implemented in Basse-Casamance, with a view of improving the livelihoods of the rural people. In many cases, however, they have proved to be ineffective and inefficient
Sarr, Serigne Momar. "Usages et conservation des communs en contexte de changement climatique dans le delta du Saloum au Sénégal." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAG028.
Full textThis PhD thesis explores the management and use of commons in relation to the collective benefits derived from their exploitation in the context of climate change in the Saloum Delta, in central-western Senegal. The research is based on a theoretical framework built on the theory of the governance of the commons, to which we combined approaches of psychosociology of social representations, socio-anthropology of development, and sociology of social transaction. The research was conducted in the Saloum Delta, which is formed by an interlacing of islands rich in biodiversity but vulnerable to climate change. In addition, social dynamics show the drive with which women, youth and development projects produce the everyday. Building on an epistemological posture based on the ‘paradigm’ of complex thought and the perspective of a ‘subjectal knowledge,’ the research methodology is primarily qualitative with an ethnographic approach. Based on a case study, the use of a set of tools (documentary review, observation, individual and group interviews) produced a diversity of discursive and factual data. The analysis of the data collected in the field was conducted with a focus on the following dimensions: organisational settings, action and interaction relations in collective action, intentionality and uncertainty of social practices, historicity, space, and forecasting. Research findings show that commons (fishery and forestry), despite a constraining context of climate change and the existence of differential social representations resulting from the presence of a multiplicity of actors in the Saloum Delta, are successfully managed by community organisations and groups of actors working together, including social, state and non-state actors. This is done through social transactions for the conservation of natural resources through a ‘negotiated order’ of sustainability on the one hand, and the uses of collective benefits derived from their exploitation to carry out community projects on the other hand. In fact, collective action of various social and institutional actors – which has been referred to as ‘socio-institutional connection’ – is a condition for the successful management of commons. It is also an adaption strategy to climate change by the social construct of space based on the historicity of the Niominka community – the main group in this region. Furthermore, relations among various actors and with environmental objects such as natural resources and space require the object of sociology to be extended and an interest in facts of nature after the psychosociological approach gains acceptance. For now, this is only possible with inter- and transdisciplinarity in environmental science starting from the concept of vulnerability
Thiaw, Diatou. "Vulnérabilité et Adaptation des territoires aux effets du changement climatique.Incitations globales, stratégies locales. Perspectives pour un développement territorial axé sur un suivi de l’utilisation de l’espace et des ressources dans les Communes de Mbour, Saly et Malicounda (Sénégal)." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV018/document.
Full textThe coast is now affected by different phenomena. Flooding, coastal erosion, biodiversity loss, land degradation ..., are all factors malfunction.The issues are both ecological, socioeconomic and political. The observation on urban and rural areas of Mbour, Saly and Malicounda shows vulnerabilities of both natural and anthropogenic. The observed changes may be specifically the effect of climate change; they also represent a continuation of situations switched by physical, social, economic, political, of territories. According to the perturbations studied, territories appear differently vulnerable. The destruction of homes and infrastructure, declining catches, revenues from fishing, tourism and agriculture are the impacts faced by different actors. The strategies developed are generally neither proactive nor effective. It also poses a problem of responsibility of actors in the mastery of disturbances and their dynamics in this strategic area economically. For a good risk management, this thesis calls for a real policy of regional planning and the establishment of an observatory
Diallo, Alassane. "Changement climatique et migrations humaines au Sénégal : une approche en termes de vulnérabilité du système socio-écologique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAE004/document.
Full textClimate change and human migration are two major issues of our time. Starting from the observation of a dichotomous knowledge between maximalists and minimalists, which results in a limited capacity of scientific research to take into account the dynamic and complex interactions between climate and human migrations, this thesis proposes a better understanding and explanation of the climate-migration relations through a renewed and integrative approach (the vulnerability of the socio-ecological system). It aims to fulfill two objectives. On the one hand, to produce new knowledges those take into accounts socio-ecological interactions and feedbacks at different spatial and temporal scales and, on the other hand, to propose a quantified instrumentation of these social-ecological interactions and feedback. This contribution could serve as a starting point for a decision-making tool to evolve towards more targeted and effective policies.This thesis emphasizes a certain difficulty in highlighting a robust relationship between climate change and migration in the Sahel region. This latter, often seen as a relatively homogeneous entity, presents complex socio-economic and physical-climatic spatial heterogeneities that do not allow a stronger understanding of migratory movements which are in change since the 1970s. For this purpose, a reduced complexity model, based both on a partitioning of the study area (Senegal) and a partitioning of data (agro-ecological zones and regions of Senegal), is mobilized as a framework for the analysis of social-ecological migrations in terms of vulnerability induced by climate change. Thus, the innovative heuristic framework built (knowledge model with a sequencing of variables) has made it possible to instrument the climate-migration relationships within Senegal.Our results show an accelerating/amplifying climatic effect of interregional migrations underlying the living conditions of populations. In general, climate alone is not sufficient to "produce" migration. The climatic effects channel through the socio-economic variables (initial vulnerability). Under these results, we retained in fine the name of "eco-climatic migrants". Thus, policies relating to eco-climatic migration in this western part of the Sahel should move towards both: (i) development issues by reducing socio-economic vulnerabilities (poverty and inequality) by acting on the environment and the populations consistently and extensively respectively; and (ii) climate economics issues by reducing the physical-climatic vulnerability through appropriate mitigating and adapting policies to face climate change
Ndiaye, Abdourakhmane. "Changements climatiques : de la modélisation du phénomène à son éducation. Application au cas des enseignants sénégalais du primaire. Le climat, du savoir scientifique aux modèles d’intégration assignée (Integrated Assessements Models) 1 Environmental education to education for sustainability development : challenges and issues Education for sustainable development : a conceptual and methodological approach De l’éducation au développement durable (EDD) aux Objectifs du Développement Durable (ODD), de nouvelles prescriptions pour les pays du Sud ? Integrated assessment models and other climate policy tools Eduquer aux changements climatiques au Sénégal, une initiation au modèle REDOC via les représentations sociales." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAD007.
Full textOur research has been focused on clarifying the scope, characteristics and principles of Climate ChangeEducation for Sustainable Development (CCESD) in order to implement curricula. This issue is part ofa dual framework : an interdisciplinary approach (linking Climate Science, Economics and EducationSciences) and the integration of CCESD into the primary cycle of the Senegalese education system. Ourresearch methodology was based on two inputs : the dynamics of complex systems (Forrester, 1969,Morin, 1977, 1980) to provide knowledge and the REDOC model (Representations, EducationalApproach, Didactic Tools and Skills) to understand teachers’ representations. The results of our researchled us to identify two postulates, facilitating a CCESD. On the one hand, the register of knowledge thatmust be activated to implement CCESD (four types : scientific knowledge, institutional knowledge,measured knowledge and pedagogical knowledge). On the other hand, the analysis of learners'representations is a necessary and essential step to set up a diversified and complementary set ofpedagogies, develop appropriate didactic tools and propose a contextualised skills referenceframework. In our research, the representations of Senegalese primary school teachers were discussedon the basis of a survey. We highlighted their representations of sustainable development, climatechange or global warming. In the case of Senegal, we observed that the issue of climate change had tobe linked to other controversial issues in the school system : the status of teachers, the quality ofinfrastructure, the issue of public health, the problem of the lack of school canteens, etc. Another wayof reminding us that the goals of sustainable development (SGD) are systemic and that qualityeducation (SDG 4) can be a key driver for change
Lo, Seen Chong Danny. "Caractérisation du fonctionnement de la végétation à l'échelle régionale en liaison avec l'observation satellitaire : [thèse soutenue sur un ensemble de travaux]." Toulouse 3, 1994. http://www.theses.fr/1994TOU30023.
Full textNdao, Mariétou. "Dynamiques et gestion environnementales de 1970 à 2010 des zones humides au Sénégal : étude de l'occupation du sol par télédétection des Niayes avec Djiddah Thiaroye Kao (à Dakar), Mboro (à Thiès et Saint-Louis)." Thesis, Toulouse 2, 2012. http://www.theses.fr/2012TOU20018/document.
Full textThe “Niayes”, coastal wetlands of Senegal, constitute fragile ecosystems that are rich inbiodiversity while traditionally being gardening areas in the “Sahelien” environment. The bigdrought of the 1970s that struck all the Sahel countries also affected the “Niayes” by an influxof rural populations coming from inside the country in search of livelihood. Besides theextreme drought, mass migration considerably increased the proprietary pressure and at thesame time generated an uncontrolled urbanization, especially around the big agglomerationsand agricultural development: both of them undermine the environmental value of thesecoastal ecosystems. In recent years, we have witnessed particularly rainy seasons. This returneof rainfall involved in urbanized areas causes flooding, accompanied by precarious sanitaryconditions for the most unprivileged populations. The rainfall variability, risk of naturalappearance, is added to anthropogenic risk factors such as the non-mastered regionalplanning, the failure of the regulatory framework, and the pollution from various agriculturaland industrial sources.This thesis, after having introduced the concept of wet zones and having presented the Niayesof the Great Coast in general, and of the three study areas (Pikine, outskirts of Dakar; Mboro,Thies region; and Saint-Louis) in particular, traces their environmental problems and variouspolitical differences. Land use of the Niayes is analysed by using remote sensing data for theperiod 1986-2010 to confront its evolution to the management of the sensible ecosystems andquestion the relevance of the implemented politics in the spirit of sustainable development
Marega, Oumar. "Changements socio-environnementaux et évolution des pratiques agropastorales en Afrique sahélienne : étude comparée entre le Ferlo (Sénégal), le Gourma (Mali) et le Fakara (Niger)." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC228/document.
Full textIn a biophysical context characterized by important socioenvironmental changes, the main objective of this PhD is to understand how much agropastoral practices modulatein space and time the vulnerability and adaptability of agroecosystems and sahelians agropastoral societies. To reach this target, this question has been applied at macro-regional scale, relying on three micro-regional study areas: Ferlo (Senegal); Gourma (Mali) and Fakara (Niger) in which perceptions and representations of societies have been studied in a sample of villages and camps. The method developed in this PhD has two components: 1) remote sensing mapping based on satellite image processing, and 2) geo-textual analyses based on lexicometry from semi-structured interviews. The remote sensing mapping allowed to diagnose micro-regional and local scales on land cover change since the 70s until 2010. The diagnosis, based on a multiscale approach, shows intra and inter regional contrasts in the evolution of soil cover by vegetation that invite to nuance observations indicating a greening of Sahel. The articulation of remote sensing with field investigations helped to understand, first the evolution of plant resources, then to consider the variety of responses from the Sahel rural societies to the 70’s and 80’s climate crisis, and to the recent socio-economic changes experienced by sahelian countries. Through lexicometry, geo-textual analysis based on semi-structured interviews allowed to approach the livestock farmer’s perception about the vulnerability and resilience of natural resources. Thanks to the expressed perceptions, the adaptive practices were identified in their variety. It enabled to show the sociospatial reconfigurations in the trajectories of agricultural and pastoral activities that partly explain the contrasts within and between regions observed in Ferlo, Gourma and Fakara
Azzoug, Moufok. "Reconstitution des variations multidécennales et saisonnières de la mousson ouest-africaine au cours des deux derniers millénaires à partir de l’étude sclérochronologique des amas coquilliers fossiles dans le delta du Saloum, Sénégal." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20142.
Full textThe multidecadal and seasonal variations of the West African Monsoon (WAM) in the last two millennia remain poorly documented in the Sahel region because paleoclimate archives are lacking. For this, we propose in this PhD thesis a sclerochronological study of the mollusk bivalve Anadara senilis from massive shell middens to reconstruct multidecadal and seasonal variations of hydrological conditions in the Saloum Delta (Senegal) between AD 460 and 1090. Hydrological conditions in this hypersaline estuary are highly sensitive to the WAM variations.Past hydrological variations are reconstructed by using isotopic composition (δ18O, δ13C) of modern and fossil shells in this Delta. The shells' seasonal isotopic signals reflect faithfully hydrological variations, linked to monsoonal regime. Our results show that the variations of these seasonal isotopic signals, associated to shell growth patterns with known periodicities allow the reconstruction of season durations with a precision of 25 days, a precision that has never been achieved in paleoclimate studies in the Sahel region.Multidecadal variations of hydrological conditions are reconstructed by using isotopic composition of fossil shells collected in the massive shell middens (Dioron Boumak), characterized by high accumulation rate. The averaged δ18O value of fossil shells was more negative by 1.4‰ compared to modern shells' isotopic signature. This result indicates fresher mean conditions in the Saloum Delta that was likely not hypersaline as it is today. The precipitation-evaporation budget was thus more positive in response to a more intense and/or longer rainfall season during from AD 460 to 1090. We propose that winter and early spring rainfall events, which are observed very occasionally today, were occurring frequently during this period. These rains restricted to the western Sahelian coast and followed by the monsoon would have increased the total duration of the rainy season (~ 5 months instead of 3 months today) and substantially increased the annual precipitation-evaporation budget.This study shed light on the high potential of A. senilis as a high resolution paleoclimate archive of rainfall variability in the Sahel region. It shows also the importance of rainfall seasonality in past hydrological cycles that should be taken into account in the future paleoclimate studies
Fall, Ababacar. "Le Ferlo sénégalais : approche géographique de la vulnérabilité des anthroposystèmes sahéliens." Thesis, Paris 13, 2014. http://www.theses.fr/2014PA131028.
Full textThe pastoral anthroposystem of Senegalese Ferlo evolves in an environment historically neglected by agricultural policies because of its characteristics particular biophysics, unfavorable to the agriculture and to the shape of development other than the extensive breeding. This primacy of the itinerant breeding is nowadays more and more disputed by the development of the farming in a context marked by the improvement of the conditions of the rainfall in West-African Sahel, soil depletion in the Groundnut Basin and the multiplication of agricultural development at the valley of the Senegal River. By combining the analysis of remote sensing imagery for mapping land cover changes by the vegetation cover, the study of flora and vegetation landscape and the exploitation of the investigations in villages and camps, this thesis attempts to define the geography of the vulnerability of rural populations and ecosystems which they use. So, pastoralists evolve with daily adaptation strategies in these circles inside Senegal marked by deep ecological instability and by the transformations at work in the Senegalese rural society. These socio-environmental changes contribute to the dynamics of plant landscapes and raise the question of ecosystem degradation
Lo, Cheikh Ibrahima. "Répertoire des bactéries identifiées par Maldi-Tof en Afrique de l'Ouest." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM5051/document.
Full textThe Africa bacteria repertory is unfamiliar because the available tools in this region are not allowed its best knowledge. In fact, bacteria are most often identified using culture techniques on simple media and biochemical tests which enable the identification of some common characters. These methods do not facilitate an exhaustive knowledge of the bacterial repertory; consequently they have recently been revolutionized by the systematic use of MALDI-TOF mass spectrometry (MS).In our thesis we used two mass spectrometers, respectively, MALDI-TOF Vitek MS currently installed at Dakar (Senegal) and MALDI-TOF Microflex LT installed in Marseille (France). In addition we have also confirmed that MALDI-TOF is a powerful tool for identifying bacterial species rarely involved in human infectious diseases. Thus in adopting the MALDI-TOF as a first-line tool in bacterial identification before Gram staining or other techniques of phenotypic identifications based on chemical characteristics, we discovered seven new species of bacteria isolated for first time in humans. Microbial identification using MALDI-TOF MS is currently feasible in Africa. Its performance and effectiveness in routine diagnosis of clinical microbiology laboratories have been proven. It is necessary either to increase the installation of MALDI-TOF, or establishing a network around a shared MALDI-TOF platform between several structures located in the same area, especially in the underdeveloped countries of Africa amortization of investment costs of the device, because it allowed reducing the time of reporting results and indirectly facilitating better care for patients
Sarré, Abdoulaye. "Approche acoustique de la dynamique et la distribution spatiale des ressources halieutiques de petits pélagiques dans l'upwelling sénégalo-mauritanien." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0062/document.
Full textAlong the coast of North-West Africa, among the richest waters over the word, fish supply is important at both socio-economic and cultural levels. In this region, the small pelagic fish are the most abundant marine resources and are monitored using hydroacoustic stock assessment methods since more than three decades. These surveys have allowed providing to local authorities a sound scientific basis for deciding about the management of pelagic fisheries. A specific challenge is to know the representativity of these surveys with respect to the stocks targeted. In this work, we confirm this representativity for Sardinella aurita stock while for S. maderensis, a part of the stock could have not been sampled and for pour Ilisha africana and Ethmalosa fimbriata these surveys are not the best tool. Furthermore, Northward shifts in the distribution of sardinella in the Canary Current Large Marine Ecosystem are recorded in this work and have been attributed to the redistribution of upwelling intensity and productivity, resulting in the abundance of sardinella decreasing in the inter-tropical coastal region. Here for the first time using independent observational time series, we report a robust northward shift in S. aurita since 1995 and attribute it to the strong ocean warming in the region. The observed spatial shifts in biomass in the last 20 years are of the same order of magnitude as those recorded for surface isotherms. Such changes will impact policy considerations in the management of food security in several West African countries and should be considered with respect to “Intended Nationally Determined Contributions”
Mbaye, Linguère Mously. "Essays on the Economics of Migration from Developing Countries." Thesis, Clermont-Ferrand 1, 2013. http://www.theses.fr/2013CLF10420.
Full textThe aim of this thesis is to study through four essays the economics of migration from developing countries. The first chapter assesses the effect of natural disasters (mainly due to climate change), in developing countries, on migration rates and looks at how this effect varies according to the level of education of people. Our results show that natural disasters are positively associated with emigration rates and also involve the migration of highly skilled people. The second chapter presents the different channels explaining the intention to migrate illegally. One of the novelties of the analysis is that it uses a tailor-Made survey among urban Senegalese individuals. We find that potential illegal migrants are willing to accept a substantial risk of death and tend to be young, single and with a low level of education. We also show that the price of illegal migration, migrant networks, high expectations, tight immigration policies and the preferred destination country all play a role in the willingness to migrate illegally. The third chapter completes the second one by studying the role of risk-Aversion and discount rate in illegal migration from Senegal. Our results show that these individual preferences matter in the willingness to migrate illegally and to pay a smuggler. Finally in the fourth chapter, we are interested in the effect of migrants on credit markets in a rural Senegalese context. According to our results, having a migrant in a household increases both the likelihood of having a loan and its size, whether the loan is formal or informal. We also find that this positive effect remains significant no matter if the loan is taken for professional activities or simply to buy food
Fabre, Coline C. "L'adaptation des agriculteurs vivriers du Sénégal au changement climatique : cas de la communauté rurale de Sessène." Thèse, 2010. http://hdl.handle.net/1866/4537.
Full textSenegal is located in a sudano-sahelian region vulnerable to climate change that renders agriculture, the country's main activity, precarious. In fact, changing climate conditions, particularly since the late 1960s, have considerably weakened the agricultural sector, which is mostly subsistence and pluvial in nature. Because of the importance of the country’s subsistence agriculture, it is imperative to know how subsistence farmers in Senegal have changed or will change their practices in order to satisfy their nutritional requirements in the context of climate change and variability. This study was undertaken in the rural community of Sessène using a qualitative approach composed on interviews, participant observation and phenomenological analysis. The research revealed the general characteristics of the agrarian families and farms, demonstrated how farmers dealt with climate change in the recent past and how they envisage doing so in the next few years, all aimed at contributing to a discussion of their adaptive capacity. In response to the shortening of the rainy season, the decrease in rainfall, the increased frequency of extreme events and the impacts of these changes on the natural environment, subsistence farmers are adopting both technical and socio-economic measures.