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Open AccessArticle

Investigation of Short-Term Evolution of Soil Characteristics over the Lake Chad Basin Using GRACE Data

1
ISSI (International Space Science Institute), 3012 Bern, Switzerland
2
GET (UMR 5563), Université de Toulouse, UPS/CNRS/IRD/CNES, 31400 Toulouse, France
3
Équipe-projet ENDSUM, CEREMA, 76120 Le Grand Quevilly, France
4
École des Ponts-ParisTech, Laboratoire Navier/CERMES (UMR 8205), 77455 Marne-La-Vallée, France
5
CESBIO (UMR 5126), Université de Toulouse, CNES/CNRS/IRD/UPS, 31400 Toulouse, France
*
Author to whom correspondence should be addressed.
Remote Sens. 2018, 10(6), 924; https://doi.org/10.3390/rs10060924
Received: 30 April 2018 / Revised: 4 June 2018 / Accepted: 5 June 2018 / Published: 12 June 2018
(This article belongs to the Special Issue GRACE Facing the Challenge of Extreme Spatial and Temporal Scales)
In the Sahelian region, the West African Monsoon (WAM) is an important phenomenon for land water storage evolution, as demonstrated by The Gravity Recovery and Climate Experiment (GRACE) estimations. The Monsoon leads to an annual increase of the water mass. However, GRACE data also displays the existence of a semi-annual cycle whose its origin is still uncertain. This cycle is characterized by a gain of water mass at the beginning of the dry season. In this study, 10-days GRACE data are used to understand the characteristics of this semi-annual cycle. Investigations of the rainfall events, rivers discharge peaks, and the Lake Chad water level variations suggest that they are not at the origin of this cycle. However, MODIS evapotranspiration data display an increase each 6 months, during the rainy season, and at the same time as the semi-annual cycle estimated by GRACE. This increase occurs in regions where the amount of clays at the surface exceeds 30%. The link between both signals and the proportion of clays at the surface leads us to the conclusion that the seasonal variation of the vertical permeability of clays controls the amount of water present in the unsaturated zone. View Full-Text
Keywords: seasonal vertical permeability; GRACE; evapotranspiration; clays; Lake Chad basin seasonal vertical permeability; GRACE; evapotranspiration; clays; Lake Chad basin
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MDPI and ACS Style

Lopez, T.; Ramillien, G.; Antoine, R.; Darrozes, J.; Cui, Y.-J.; Kerr, Y. Investigation of Short-Term Evolution of Soil Characteristics over the Lake Chad Basin Using GRACE Data. Remote Sens. 2018, 10, 924.

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