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Thesis/Dissertation: BibTeX citation key:  Amogu2009a
Amogu, O. (2009) Dégradation des espaces sahéliens et conséquences sur l'ensablement du fleuve Niger. Grenoble, Université Joseph Fourier.
Added by: Fanny Lefebvre 2010-09-16 16:55:47    Last Edited by: Fanny Lefebvre 2010-11-25 11:56:16
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Categories: General
Creators: Amogu
Publisher: Université Joseph Fourier (Grenoble)

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Abstract
In order to achieve the overall objective of this research which was to gain an understanding into the impact of land cover change on sediment production and transport in the middle Niger River basin, the application of various approaches was necessary. These approaches included the study of hydrological data (1929 – 2008) and land cover data (1965 – 2000), in addition to the measurement of sediment characteristics (2005-2008).The study focused on two Sahelian subbasins(the Gorouol and the Sirba basins) in comparison to a Sudanian basin (the Mékrou basin). An evaluation of the evolution of land cover by remote sensing techniques showed an increase in disturbed bare soil surfaces favouring an increase of sediment transfer to the middle Niger via conventional tributaries as well as ungauged ephemeral streams that have increased in number and size since the 1970s. Field measurements of sediment characteristics where carried out at ten locations along the middle Niger River and some of its tributaries in order to quantify the sediment flux and sources in the study area. Hydrological analyses showed the impact of the reduction of precipitation on river discharge, with the most recent dry period, resulting in the alteration of the Niger River’s regime at Niamey and affecting river planform. The sediment flux analysis for the middle Niger River points to the existence of other significant sediment sources apart from the main tributaries. A simulation of the sediment transporting capacity, by grain size class, using data from a 1-D model of the river enabled the localization of areas of sediment equilibrium and deposition, when compared to measured sediment concentration values.
Added by: Fanny Lefebvre    Last Edited by: Fanny Lefebvre