期刊名称：Science et changements planétaires / Sécheresse
印刷版ISSN：1147-7806
电子版ISSN：1777-5922
出版年度：2009
卷号：20
期号：1
页码：131-138
DOI：10.1684/sec.2009.0171
出版社：John Libbey Eurotext
摘要：Figures See all figures Authors Jean-Louis Rajot , Harouna Karambiri , Olivier Ribolzi , Olivier Planchon , Jean-Pierre Thiebaux IRD, UR 176 Solutions Université Abdou-Moumouni (UAM) IRD, BP 11416 Niamey Niger, 2iE (Groupe EIER-ETSHER) UTER GVEA 01 BP 594 Ouagadougou 01 Burkina Faso, IRD UR 176 Solutions IRD-IWMI-NAFRI BP 06 Vientiane Laos RDP, IRD UR 176 Solutions Po Box 1025 Kasetsart University Bangkok 10903 Thailand Key words: Sahel, water erosion, wind erosion DOI : 10.1684/sec.2009.0171 Page(s) : 131-8 Published in: 2009 In the Sahel, sandy soils are widespread and support not only most of the pearl millet production, the major staple crop in the region, but also grass production for livestock. Parent sediments of these soils have an aeolian origin and are hence prone to wind erosion. Still, their clay content, even though very low, allows physical crust formation during rainfall leading to runoff and water erosion. Squall lines, major rainfall events of the rainy season, are usually preceded by intense wind. Wind and water erosions are therefore closely associated in both time and space, but they are rarely studied simultaneously. Erosion measurements were performed for two years (2001, 2002) on a small catchment of grazing land (1,4 ha) at Katchari, Burkina Faso, a location typical of the Sahel area with under 500 mm annual rainfall. Wind erosion occurs at the onset of the rainy season, from May to 15th of July, when soil cover is the lowest and before the growth of vegetation. On this non-cultivated area, the same dynamic unfolds as that recorded in millet fields in other sahelian studies. Water erosion occurs throughout the rainy season, but certain intense events produce most of the total annual erosion. Wind causes the largest sediment fluxes leading to both erosion (up to 20 Mg/ha per year) and deposition (up to 30 Mg/ha per year) depending on the area in the catchment. Water erosion is one order of magnitude lower than wind erosion and is more intense where wind erosion is highest. Hence, the same area is eroded by both wind and water. Conversely, areas where aeolian deposition occurs are less affected by water erosion and correspond to fertile islands where vegetation grows. From this study, it comes out that there is on the whole no land degradation at the catchment scale, but an intense aeolian and water dynamic leading to substantial spatial variability typical of sahelian landscapes.
