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sur le développement des zones arides et semi-arides

Titre : Urbanization Process of a West African Savanna Town : Dynamics and Consequences of Hyper-Urbanization. Case Study of Gombe in Northeast Nigeria

Der Verstädterungsprozess einer westafrikanischen Savannenstadt : Dynamik und Folgen der Hyperurbanisierung am Beispiel von Gombe in Nordostnigeria

Auteur : Balzerek, Heiko

Université de soutenance : Ruprecht Karls Universität Heidelberg

Grade : Doktorgrade 2003

Résumé
The highly rapid growth of African towns results in an increasing imbalance in the symbiosis of man and nature. Furthermore, a profound change in the way of the residents’ coexistence is to be observed. The economic improvement anticipated by the community mirrors the ongoing process of urbanization. Its consequences can be found in all public spheres and cause a socio-economic transformation, which in turn brings about a drastic restructuring of the settlement physiology. This process causes a radical change in the ecosystem and new precarious tensions within the society. Because of its particular scope leading to an increased social vulnerability and a reduced natural carrying capacity we must consider this development as a process of “hyper-urbanization”. For scientific reasons the approach of different human and physical geographic disciplines as well as modern methods of satellite remote sensing, geographic information systems, and a household based social area analysis were applied. This multi-method approach allows to detect and analyse micro-regional change in time and space and the development trends of its progress direction – based on individual interaction among the population as well as interaction with the environment. This paper examines the case of the dynamic population growth in Gombe town – located in the predominantly Muslim northeast of Nigeria – representative for many urban centres in the West African Savannah defined by their high number of residents, doubling every 12 to 15 years. Furthermore, the research about Gombe emphasizes the cause and effect of hyper-urbanization. Social phenomena, as there are alienation of the urban community, modified educational attitude, ethnic biasing of the labour market, return to tribalism, social gap expansion, vertical mobility between the social strata, segregation processes, etc. are described as consequences of increasing intercultural immigration from all parts of the country, an important stimulus for the overall economic and social development. Moreover, this process of socio-economic transformation causes a profound cultural change within the urban community. In Gombe, a fragmentation of the community is to be observed, dividing the society into two large groups : one favouring cultural persistence, the other orientated towards transformation. These two groups are distinguishable according to diverse criteria, i.e. social, economic and demographic characteristics as well as further features as the level of education, religion, prosperity and their place of residence. Education and professional qualification, in contrast to access to resources and power, belong to the modern determinants facilitating social advancement. Unfortunately, these new factors also stir up social tensions between neighbours and can easily lead to open violence. The re-organization of the spatial structure by intensive land use change in Gombe’s periphery reflects the urban intrusion into the peri-urban zone. The ongoing modification of the settlement structure is strongly associated with the population growth rate, which – exceeding the bench mark of 300,000 inhabitants in the year of 2000 – can be determined at 6% annually. The clearing of huge forest reserves – originally created to stop gully erosion along the slope above Gombe – has to be seen in combination with the new economic utilization interests, mirrored by speculation for building land and the highly dynamic real estate market. Drastic ecological shifts in regions like the Sudan zone, suffering from unfavourable constellations of geographical factors, often lead to an irreversible degradation of nature. The increase of natural catastrophes and their impact on urban life can be immense. The annual floods in Gombe take their toll on humans and animals ; floods and streams undercut buildings, roads and bridges near the banks of gullies and lead to their collapse. The continual process of deep-cutting erosion in already deeply cut gullies results in a fast drainage of the ground aquifers, leading to the lowering of ground water tables and the subsequent drying up of wells, still the primary water source for the inhabitants. The scarcity of well water in addition to the inadequate water supply system intensifies the growing health risk and social vulnerability. The annual epidemics of cholera, typhoid fever, diarrhoea as well as the high rate of infant mortality dramatically point out the realistic threat to the health of the whole community, and especially of the most vulnerable low income groups.

Mots clés : Vulnerability , socio economic transformation , urban satellite remote sensing , hyper-urbanization , Ikonos

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