Mise en évidence des zones touchées par la désertification par télédétection à basse résolution au Niger

Hountondji, Yvon-Carmen; Ozer, Pierre; Nicolas, Jacques

doi:10.4000/cybergeo.2761

Cited by 13 publications

(10 citation statements)

References 39 publications

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“…In contrast, Hein and De Ridder (2006) used the RUE concept (Rain Use Efficiency) to make satellite information more consistent with the numerous studies that highlighted a severe reduction in vegetation cover over the Sahel (Ada and Rockström 1993, Loireau 1998, Chinen 1999, Leblanc et al 2008, Le Breton 2012. This observation corroborates the findings of previous studies by Hountondji et al (2004) in Niger. In western Niger, total herbaceous yield was shown to be increasing despite the land clearing, because of the increase in crop area (Hiernaux et al 2009a).…”

Section: Introductionsupporting

confidence: 96%

Runoff evolution due to land-use change in a small Sahelian catchment

Amogu

Estèves

Vandervaere

et al. 2014

Hydrological Sciences Journal

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International audienceLand-use changes have been significant these last decades in West Africa, particularly in the Sahel region; in this area, climatic and demographic factors have led to a rise in cropped areas in recent decades causing strong changes in the water cycle and in river regimes. This study compares the rainfall-runoff relationships for two periods (1991-1994 and 2004-2011) in two small and similar neighbouring Sahelian catchments (approx 0.1 km(2) each). This allows identification of the different hydrological consequences of land-use/land-cover change, particularly the fallow shortening and the consequent degradation of topsoil. The main land surface change is a 75% increase in crusted soil area. Runoff increased by more than 20% on average between the two periods while flood duration decreased by 50% on average. However, runoff values remained largely constant in the lower part of the northern basin due to a strong increase in in-channel infiltration

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Section: Introductionsupporting

confidence: 96%

Runoff evolution due to land-use change in a small Sahelian catchment

Amogu

Estèves

Vandervaere

et al. 2014

Hydrological Sciences Journal

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“…As shown in most of the literature, there is a general re-greening in the whole Sahel except in Niger and central Sudan. The western part of Niger is also commonly observed as an area with decreasing NDVI values, as observed by Hountondji et al [82] and Dardel et al [83] (Figure 8). Clearly, extended areas of the Iullemeden basin east of Niamey (left bank of the Niger River) are experiencing an ongoing desertification of the ferricrete plateaus (or at least a decrease in vegetation cover), the sandy soils basin and valleys showing a slight increase in woody plants [14] are far from compensating the strong decrease in vegetation cover observed from 1965 to 2010 in both areas, as well as in the slopes of the Niger River valley and lower basins of right bank tributaries [72].…”

Section: Some Concepts In Land Use/land Cover Change Studiessupporting

confidence: 56%

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

Descroix

Guichard

Grippa

et al. 2018

Water

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Abstract:In the West African Sahel, two paradoxical hydrological behaviors have occurred during the last five decades. The first paradox was observed during the 1968-1990s 'Great Drought' period, during which runoff significantly increased. The second paradox appeared during the subsequent period of rainfall recovery (i.e., since the 1990s), during which the runoff coefficient continued to increase despite the general re-greening of the Sahel. This paper reviews and synthesizes the literature on the drivers of these paradoxical behaviors, focusing on recent works in the West African Sahelo/Sudanian strip, and upscaling the hydrological processes through an analysis of recent data from two representative areas of this region. This paper helps better determine the respective roles played by Land Use/Land Cover Changes (LULCC), the evolution of rainfall intensity and the occurrence of extreme rainfall events in these hydrological paradoxes. Both the literature review and recent data converge in indicating that the first Sahelian hydrological paradox was mostly driven by LULCC, while the second paradox has been caused by both LULCC and climate evolution, mainly the recent increase in rainfall intensity.

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“…In particular, images from the Advanced Very High Resolution Radiometer (AVHRR) on board the National Oceanic and Atmospheric Administration (NOAA) satellite have been widely used for global studies of Sahel/Sudanian environments due to the extensive archive (dating back to 1982), the free data, the suitable wavebands and the high temporal resolution. Using NOAA-AVHRR databases (GIMMS, Pathfinder or ARTEMIS), several authors interpreted time series of the Normalized Difference Vegetation Index (NDVI) in terms of ecosystem degradation or recovery, particularly in arid and semi-arid areas (e.g., Hountondji et al, 2004;Pouchin et al, 2002;Prince et al, 1998;Wessels et al, 2007). Because of subtle temporal variations and a broad scale signal, the results of these studies are sometimes difficult to interpret and may even appear to be contradictory.…”

Section: Introductionmentioning

confidence: 98%