Dynamique d’occupation du sol des zones humides urbanisées de Dakar (Sénégal) de 1942 à 2014

L’étude est une analyse de la dynamique spatiale de l’occupation du sol des zones humides (Niayes) de Dakar de 1942 à 2014 par l’utilisation d’outils de la géomatique. Nous avons exploité les photographies aériennes des années 1942, 1966 et 1978 et les images satellitaires des années 2003 et 2014 pour une cartographie de l’occupation du sol. Les résultats d’analyse montrent que la grande sécheresse des années 1970 a modifié l’hydrologie des Niayes et entraîné une régression des zones inondables. La surface de ces dernières varie de 35,84 % en 1942 à 5,44 % en 2003. À partir de 2003, l’urbanisation accrue de la zone a réduit progressivement la superficie qui était occupée par les Niayes bien que l’eau ait progressé de 9,25 % en 2014. À cette date, le bâti prédominait à 37,27 % dans la zone au détriment des surfaces nues, de l’eau et surtout de la végétation. La densification du réseau routier constitue le principal facteur de fragmentation des Niayes et la principale porte d’entrée à leur occupation.The study is an analysis of the land cover spatial dynamics of the wetlands (Niayes) of Dakar from 1942 to 2014 by the use of geomatic tools. We used the aerial photographs of the years 1942, 1966 and 1978 and the satellite images of the years 2003 and 2014 to establish land-cover maps. The results of the analysis show that the big drought of the 1970s affected the hydrology of the Niayes and brought a decrease in the extent of the flood-prone areas. The surface of the latter varied from 35.84 % in 1942 to 5.44 % in 2003. From 2003, the increased urbanization of the area gradually reduced the area that used to be covered by the Niayes although flooded areas rose by 9.25% in 2014. At that time, the built-up area prevailed with 37.27% at the expense of bare areas, waters surfaces, and especially woodlands. The densification of the road network is the major driver of the fragmentation of the Niayes and the main entryway to their occupation

Dynamique d’occupation du sol des zones humides urbanisées de Dakar (Sénégal) de 1942 à 2014

The study is an analysis of the land cover spatial dynamics of the wetlands (Niayes) of Dakar from 1942 to 2014 by the use of geomatic tools. We used the aerial photographs of the years 1942, 1966 and 1978 and the satellite images of the years 2003 and 2014 to establish land-cover maps. The results of the analysis show that the big drought of the 1970s affected the hydrology of the Niayes and brought a decrease in the extent of the flood-prone areas. The surface of the latter varied from 35.84 % in 1942 to 5.44 % in 2003. From 2003, the increased urbanization of the area gradually reduced the area that used to be covered by the Niayes although flooded areas rose by 9.25% in 2014. At that time, the built-up area prevailed with 37.27% at the expense of bare areas, waters surfaces, and especially woodlands. The densification of the road network is the major driver of the fragmentation of the Niayes and the main entryway to their occupation

Dynamique d’occupation du sol des zones humides urbanisées de Dakar (Sénégal) de 1942 à 2014

The study is an analysis of the land cover spatial dynamics of the wetlands (Niayes) of Dakar from 1942 to 2014 by the use of geomatic tools. We used the aerial photographs of the years 1942, 1966 and 1978 and the satellite images of the years 2003 and 2014 to establish land-cover maps. The results of the analysis show that the big drought of the 1970s affected the hydrology of the Niayes and brought a decrease in the extent of the flood-prone areas. The surface of the latter varied from 35.84 % in 1942 to 5.44 % in 2003. From 2003, the increased urbanization of the area gradually reduced the area that used to be covered by the Niayes although flooded areas rose by 9.25% in 2014. At that time, the built-up area prevailed with 37.27% at the expense of bare areas, waters surfaces, and especially woodlands. The densification of the road network is the major driver of the fragmentation of the Niayes and the main entryway to their occupation

Water Resources Dynamics and Vulnerability in Rusizi National Park (Burundi) from 1984 to 2015, in the Context of Climate Change and Global Warming

The study of water resources’ dynamics and vulnerability in Rusizi national Park aimed to achieve the following objectives: (1) to identify, characterize and map water bodies, (2) to analyze and explain their periodical evolutions and (3) to analyze the spatial transformation processes affecting them. It is a contribution to the knowledge of the Park’s water resources for the development of monitoring systems and the sustainability of their functions as strategic ecosystems. It is based on the diachronic analysis of land cover from multi-date Landsat images of years 1984, 1990 and 2011 (TM), 2000 (ETM+) and 2015 (OLI-TIRS), landscape ecology tools and socio-economic and climate data. Supervised classification of images allowed the identification of 9 to 10 land cover classes including water bodies, according to years. A total number of 17 water bodies were detected from 1984 to 2015. During this period, regularly detected and dried up water bodies represent 18.2% and 54.6% respectively. The rates of water bodies’ drying up were 69.2% in 2000 and 64.2% in 2015. Water bodies are experiencing a great deterioration in number, size and stability. The Park's water coverage has decreased from 3.56% in 1984 to 2.43% in 2015. This corresponds to a decline of 31.2%. The water bodies’ stability, which was 75.70% between 1984 and 1990, represents only 42.78% between 1984 and 2015. The stability of individual water bodies is decreasing as well while low spatial connectivities are being observed between some close water bodies. The spatial transformation processes carrying these dynamics are patch enlargement, patch creation, patch attrition and patch dissection, depending on the period. Global warming, rainfall variability and farming activities like land drainage and irrigation are the most important threats to water resources

Protection internationale du climat et souveraineté étatique

La protection internationale du climat, de par ses enjeux de dimension mondiale, interroge inévitablement la capacité de la communauté internationale à s’en saisir, les méthodes et sources du droit international ainsi que son effectivité et plus largement notre conception de l’ordre juridique international. Alors que le droit international est un droit encore jeune et donc parfois contesté dans son objet et bien sur dans ses résultats, il doit répondre à des enjeux considérables qui dépassent largement ce pour quoi il a été historiquement conçu : un droit de la guerre puis un droit de la coexistence pacifique et à présent un droit favorisant l’harmonie dans les relations internationales pour poursuivre – éventuellement – un intérêt supérieur aux États qui pourrait être l’intérêt général de l’humanité. Il demeure cependant, dans ses origines et ses fondements, intrinsèquement, génétiquement même, interétatique