The Sahelian drought may have ended during the 1990s

Ozer, Pierre; Erpicum, Michel; Demarée, Gaston R.; Vandiepenbeeck, Marc

doi:10.1623/hysj.48.3.489.45285

Cited by 94 publications

(63 citation statements)

References 11 publications

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“…Many studies conducted on pluviographic and hydrographic series in the region (Hubert and Carbonnel, 1987, Paturel et al 1997 have shown the presence of a number of breaks in the series, corresponding to increases (early 1920s and late 1940s) or decreases (in the late 1930s and late 1960s) of yearly averages. Recently, higher averages in the mid-1990s have been highlighted in the hydrological series of the River Senegal at Bakel, which seems to confirm the hypothesis that the Sahelian drought could have ended in the 1990s (Ozer et al 2003, Hubert et al 2007). This leads one to hypothesize the non-stationarity of these series and the existence of points of discontinuity, singularities represented in particular by changes in averages, caused by a change, be it natural or man-made, in the mechanism generating discharge.…”

Section: Introductionsupporting

confidence: 52%

“…At Bakel, they highlighted four breaks: in 1921/22, 1936/37, 1949/50 and 1967/68, while at Koulikoro four analogous breaks were identified: in 1923/24, 1932/33, 1950/51 and 1969/70 (Hubert et al 1989. The hydrological observations of the last two decades suggest that a new break has appeared in 1994/95 with a "return to the wet" (Ozer et al 2003).…”

Section: Variation Of the Flow Regimementioning

confidence: 99%

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A study on hydrological series of the Niger River

Abrate

Hubert

Sighomnou³

2013

Hydrological Sciences Journal

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The Hubert segmentation procedure has been applied to historical series of annual average discharges of the Niger River at Koulikoro (Mali), Niamey (Niger) and Lokoja (Nigeria) stations. The breaks, especially those identified at Koulikoro and Niamey, match well with those identified in the Senegal River series at Bakel using the same procedure. Lokoja departs from this regional pattern, as it shows in the late 1980s a return to wetter conditions much earlier than the other three stations. The magnitudes of the variation of the inter-annual means between the alternating wet and dry periods are significant and similar. These results seem to suggest that phenomena causing non-stationarity in hydrological series can have a sub-continental impact or, in contrast, may be more limited in their spatial coverage.

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Section: Introductionsupporting

confidence: 52%

Section: Variation Of the Flow Regimementioning

confidence: 99%

A study on hydrological series of the Niger River

Abrate

Hubert

Sighomnou³

2013

Hydrological Sciences Journal

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“…3). We applied the nonparametric statistical test of Pettitt (1979) These results correspond to the trends observed elsewhere in the Sahel of West Africa, with the start of the drought in the late 1960s (Dai et al, 2004;L'Hoˆte et al, 2002;Ozer, 2000) and wetter conditions in the early 1990s (Nicholson, 2005;Ozer et al, 2003).…”

Section: Resultsmentioning

confidence: 92%

Fifty years of landscape evolution in Southwestern Mauritania by means of aerial photos

Niang

Ozer

2008

Journal of Arid Environments

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South-western Mauritania is located in a semi-arid environment exposed to large rainfall variations and affected by a severe drought since the mid-1960s. The studied area includes the right bank of the Senegal River and the southern extension of the Saharan sandy dunes and is based on the analysis of climatic data, field studies, and four aerial surveys realized since 1954.The climatic analysis shows that, after a strong decline of yearly rainfall started in the mid-1960s, a significant increase is observed from the early 1990s. In the meantime, dust storms frequency has dramatically increased while the threshold wind speed declined as a result of vegetation contraction. The comparison of the four mosaics of aerial photos reveals the major impact of both drought and human on recent environment changes with the strong decline of the forest, the reactivation of sandy soils and the apparition of large rice fields.If the increase of active dunes activity is likely to be a consequence of the persisting drought, forest decline is more likely to be attributed to fuel wood collection in a first time, then to the creation of rice fields since the late 1980s. Although the 2003 aerial photos show a timid return of vegetation in very limited and specific areas, field surveys show that wind erosion is still very important and water erosion is developing very rapidly because of the absence of vegetation cover. r

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“…The annual rainfall amount achieved its mean level in almost all of West Africa [80,112] in 1999 [7] or during the 2001-2010 decade [4], although this is regarded as controversial by other authors, as highlighted Nicholson [105]. In fact, the controversy mostly arose because the annual rainfall recovery has been relatively recent, and so the use of different data sets (including different sites and time periods) has led to some differences.…”

Section: Annual Rainfall Amount and Indexesmentioning

confidence: 99%

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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The Sahelian drought may have ended during the 1990s

Cited by 94 publications

References 11 publications

A study on hydrological series of the Niger River

A study on hydrological series of the Niger River

Fifty years of landscape evolution in Southwestern Mauritania by means of aerial photos

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

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