Les villes n’ayant pas vocation à produire elles-mêmes leurs moyens de subsistance sont un point de départ pour l’étude du système alimentaire. L’approvisionnement alimentaire du cœur dense des métropoles participe à l’amont au métabolisme territorial, impliquant des échanges matériels entre la société organisatrice du système alimentaire et la biosphère qui la sustente. Si des analyses historiques des modalités de l’approvisionnement alimentaire de la capitale ont été produites, ses mécanismes contemporains complexes sont aujourd’hui méconnus. Un objectif de la thèse réside en l’établissement d’un récit circonstancié de la trajectoire socio-écologique de l’approvisionnement alimentaire du cœur de la métropole parisienne, de la fin de l’Ancien Régime à nos jours. Inscrites dans un paysage économique mondialisé, les aires de préhension alimentaire de Paris confirment l’existence d’une empreinte globale du système alimentaire parisien. Cependant, des initiatives récentes promeuvent un retour à un approvisionnement de proximité. Le tournant 2010-2011 marque l’essor de ces démarches nouvelles, jusqu’alors ignorées ou considérées comme marginales et anecdotiques tant par le grand public que par la plupart des acteurs décisionnaires du système alimentaire. La reterritorialisation de l’approvisionnement est issue d’une construction sociale de proximités tant géographique qu’organisée, dont les prétextes et les intérêts des acteurs qui l’encouragent sont multiples. Un second objectif est donc constitué par l’analyse des politiques de trois acteurs (public, associatif et privé) quant à l’avènement d’une transition dans le système alimentaire, impliquant un rapprochement entre les aires de production et les bassins de consommation. Prenant appui sur un cadre théorique fondé par l’écologie territoriale, l’analyse des trajectoires et transitions socio-écologiques et les apports de l’école de la proximité, cette thèse propose une vision pluridisciplinaire de l’évolution du système alimentaire du cœur de la métropole parisienne. / Cities are not meant to produce their own livelihood, and so, they are an interesting starting point to the study of the food system. Based on a threefold theoretical framework – territorial ecology, socio-ecological paths and transitions, and proximity strategies – this thesis aims at a multidisciplinary analysis attesting how the food system has been evolving inside the Paris metropolis. The thesis gives a detailed account of the food supply’s socio-ecological trajectory, from the end of the Ancien Régime to the present day. The 2010-2011 turning point settles new initiatives aiming at proximity foodsheds – which had hitherto been ignored altogether or considered marginal and minor. Reterritorialization of the supply is the result of social constructions of geographical and organized proximities. This work also investigates the policies of three food-system stakeholders (public, community and private) regarding an impending transition in the socio-ecological pathway that would imply a merger between production and consumption foodsheds.

Esta dissertação teve como objetivo principal avaliar o nível de segurança hídrica do abastecimento público de Porto Nacional/TO, associado à quantidade e qualidade de água bruta da bacia do Córrego São João, seu único manancial de abastecimento. Adotou-se o modelo conceitual e metodológico desenvolvido pelo Grupo de Pesquisa “Água, Gestão e Segurança Hídrica em tempos de Mudanças Ambientais Globais”, do qual a autora é parte integrante. O modelo baseia-se no conceito de segurança hídrica associado, de um lado, a riscos qualiquantitativos da água bruta no ponto de captação e, de outro lado, na sua compatibilidade com o sistema de abastecimento público, em particular os subsistemas de captação e tratamento. Dessa forma, foi possível avaliar, de forma qualitativa, a segurança hídrica do abastecimento de Porto Nacional-TO/Bacia do Córrego São João, perante quatro fatores de estresse: i) pressão sobre as condições ambientais; ii) demanda por água; iii) carga poluidora; e iv) eventos hidrológicos extremos (seca e inundação). Os resultados apontam que o maior estressor de risco à segurança hídrica do abastecimento de Porto Nacional se relaciona à demanda por água, pois a disponibilidade hídrica se encontra no seu limite e o uso da água a montante da captação da ETA continua a crescer. Por outro lado, constatou-se que as condições ambientais da Bacia têm sido progressivamente pressionadas, sobretudo pela agricultura e pastagens, além da notória expansão urbana. A qualidade de água e as secas/estiagens agravam esse quadro. Por fim, o principal resultado aponta para uma aparente compatibilidade entre a disponibilidade qualiquantitativa da água bruta do Córrego São João e os subsistemas de captação e tratamento da ETA 02, atualmente. Contudo, avaliou-se também que a Bacia se encontra próxima ao limite crítico, enquanto manancial de abastecimento de Porto Nacional. / The São João stream is the strategic source for supplying the municipal headquarters of Porto Nacional. This dissertation aimed to identify the main risks and vulnerabilities to the public supply of Porto Nacional / TO, associated to the quantity and quality of raw water of the Córrego São João basin, and to analyze the level of current and future water security of the municipality. We adopted the model developed by members of the Research Group "Water, Water Management and Safety in times of Global Environmental Change".Thus, it was possible to develop a methodology of analysis of water security of urban supplies, specific to the São João Stream basin in Porto Nacional / TO, considering four stress factors considered as the most determinant for current vulnerability: i) pressure On environmental conditions; Ii) demand for water; (Iii) pollutant load and (iv) extreme hydrological events. The results showed that the greatest stressor to the water security of the supply of Porto Nacional, related to the problems of quantity and quality of raw water, is the demand for water. On the other hand, the pressure on the environmental conditions of the Basin was evidenced by the preparation and analysis of maps of land use and occupation in 2006, 2011 and 2016; The evolution (in time and space) of the anthropic occupation with implantation of temporary crops and of pastures, besides the notorious urban expansion, was verified. We did not identify any records of total paralysis of ETA 02. The main result shows that, currently, there is still compatibility between the quali-quantitative availability of the raw water of the São João Stream and the subsystems of capture and treatment of ETA 02.