Urban sprawl development and flooding at Yeumbeul suburb (Dakar-Senegal)

Rapid development of urban centers in Africa is becoming a serious challenge for the coming decades with a wide range of foreseen social, economical and environmental implications. With the natural growth of the population, urban demography has been boosted by rural exodus triggered by serious droughts and increasing rural poverty. With the small resources available for an adequate urban management and the lack of efficient urban policy, Dakar capital of Senegal is characterized by an out of control urbanization process. Among the many impacts noted, flooding has appeared recently as a major threat for poor population leaving in the suburbs of Dakar. This study carried out at the outskirts of the town, in Yeumbeul District (17°24’ North, 14°46’ West), tries from rainfall variability, Digital Terrain Model and land cover change analysis since 1954 to track the interactions between natural and human causes of flooding occurring regularly since 1989. This integrated approach shows that the flooding process is not a mere climate variability related issue, it is tightly bound with poor urban management and occupation of irregular, unsuited land devoted to natural process. Satisfaction of housing needs was, for most poor rural dwellers, only possible through informal land markets, forcing them to settle in cheap yet risky lands. The recent extreme rainfall events reveal that most of these urban sprawls are located in flood prone areas. Environmental impacts of these flooded settlements have been examined. Serious flooding of 2005 has been a great momentum for the State and several other stakeholders to initiate various strategies that are discussed in this paper.Key words: Flooding, rural migration, irregular settlements, Dakar, Senegal

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Dynamiques socio-environnementales en Afrique

L'Afrique de l'Ouest subit, depuis plusieurs années, une dégradation des paysages agricoles. La forte variabilité climatique de ces dernières décennies est un des facteurs déterminants de ces transformations qui y sont observées. Les terroirs rizicoles de Basse-Casamance, emblématiques des « civilisations agraires » ouest-africaines, traduisent les dynamiques dans cette région. Ces espaces, aux nombreuses activités humaines, présentent de fortes contraintes naturelles et socio-économiques qui se répercutent sur les systèmes rizicoles. L'analyse des terroirs rizicoles, par une approche des paysages combinant données géospatiales et travaux de terrain, montre des dynamiques contrastées entre l'activité rizicole et son environnement socio-biophysique. Il ressort de l'analyse un recul des terroirs rizicoles en relation avec les changements globaux. La faiblesse de la main-d'oeuvre se traduit par le manque d'entretien des digues de protection des parcelles rizicoles. L'analyse révèle ainsi l'existence de fortes interactions entre activités agricoles, écosystèmes exploités et environnement socio-économique

International conference ICAWA 2016 : extended book of abstract : the AWA project : ecosystem approach to the management of fisheries and the marine environment in West African waters

Dynamics of the coastal arrow of the Barbary Language from 1954 to 2016 Situated on the West African Atlantic coast, at the mouth of the Senegal river delta, the sandy coastal arrow of Langue de Barbarie plays a fundamental role in the stabilization of the north coast of Senegal, and constitutes a natural rampart for the historic island city of Saint-Louis that it defends against the swells and storms of the Atlantic. However, the dynamics of the Langue de Barbarie are still complex and little known, as regards in particular the impact of the swell on the shore and the dynamic response of the latter, the contributions of sand and their redistribution by the swell through coastal drift, longshore sediment transport and its interaction with anthropogenic actions (defense works, breach ...), sedimentary bypass and sedimentary exchanges between the delta of the stream and the delta of the adjacent mouth ... which does not facilitate the forecast of scenarios of geomorphological evolution of this coastal arrow whose socio-economic and environmental stakes are unquestionably strong. The lagoon water level behind the Langue de Barbarie tended to rise considerably during a period of high flooding of the Senegal River, particularly during the rainy season, causing repeated flooding in the town of Saint-Louis and its surroundings. It was during one of these flood cycles that, on the decision of the local authorities, a breach 4 meters wide was opened on the coastal spit in October 2003, with the aim of sparing the historic island of a risk of flooding. The opening of this breach certainly made it possible to lower the water level in Saint-Louis, but reveals in consequence serious problems of management and coastal management. The dramatic enlargement of the breach resulted in the dismantling of the coastal arrow, causing the destruction of houses, infrastructure and settlements that it supports, justifying a dynamic analysis of the Langue de Barbarie

Nematóides do Brasil. Parte V: nematóides de mamíferos Brazillan nematodes. Part V: nematodes of mammals

<abstract language="eng">A survey of nematode species parasitizing Brazilian mammals is presented, with enough data to provide their specific identification. The tirst section refers to the survey ofthe species, related to 21 superfamilies, 45 families, 160 genera and 495 species that are illustrated and measurement tables are given. The second section is concerned to the catalogue ofhost mammals which includes 34 families, 176 species and their respective parasite nematodes. The identification of these helminths is achieved by means of keys to the superfamilies, families and genera. Specific determination is induced through the figures and tables as above mentioned