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De la simulation de séries climatiques en zone sahélienne à la simulation hydrologique : le cas de la reconstitution des niveaux du lac Tchad sur la période 1851-2011

Abstract : The reduction in the surface area of Lake Chad from 25,000 to 4,000 km2 between 1972 and 1987, in connection with the great drought of the 1980s in the Sahel, had a major impact on the way of life of the riparian populations, although very low lake levels had already been observed several times during the 20th century. The assessment of the hydrological response of the Lake Chad watershed to climate variability is therefore a key issue in addressing the vulnerability of Sahelian populations. In this study, the levels of Lake Chad are reconstructed between 1851 and 2011 from climatic data (precipitation (P) and temperature (T)), by a lake model whose main forcing is the Chari-Logone flow (draining 85% of the inflows to the lake), itself simulated by a rain-flow model. The lake model and rain-flow model were previously adjusted over the period 1955-2011. The climatic series used (P, T) are obtained by the analogue method. This reconstitution method consists in particular of making an analogy between atmospheric situations of the simulation period (here 1851-2011) and the observation period (here 1955-2011), in order to reconstruct the series of P and T over the whole simulation period by resampling the observed series. The lake levels simulated in this way are compared with observations over the period 1955-2011 and historical records of lake levels prior to 1955. This reconstitution of lake levels is compared with another simulation obtained this time from precipitation and temperatures simulated by global climate models of CMIP5 experiments. Confronting the methods of reconstitution of hydrology in the Sahelian zone seems relevant as the rainfall projections are divergent in this region.
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https://hal.inrae.fr/hal-02606966
Contributor : Migration Irstea Publications <>
Submitted on : Saturday, May 16, 2020 - 1:22:59 PM
Last modification on : Wednesday, November 25, 2020 - 3:34:24 AM

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  • HAL Id : hal-02606966, version 1
  • IRSTEA : PUB00056330

Citation

Camille Bouchez, P. Brigode, N. Folton, Pierre Deschamps, Julio Gonçalvès, et al.. De la simulation de séries climatiques en zone sahélienne à la simulation hydrologique : le cas de la reconstitution des niveaux du lac Tchad sur la période 1851-2011. Réunion des Sciences de la Terre 2016, Oct 2016, Caen, France. pp.2. ⟨hal-02606966⟩

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