How long does precipitation inhibit wind erosion in the Sahel?

G. Bergametti (1) , J. L Rajot (2, 1) , Caroline Pierre (1) , C. Bouet (2, 1) , B. Marticorena (1)

1 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
2 iEES Paris - Institut d'écologie et des sciences de l'environnement de Paris

Simultaneous measurements of saltation, wind speed, and rainfall performed in Niger before, during, and after 18 rain events are used to investigate how rain events affect wind erosion in the Sahel. The results show that the inhibition of saltation is rapid but progressive after the beginning of a rain event. The decrease of sand transport during the rain event is better linked to the time elapsed from the beginning of the rain event rather than to the cumulative rainfall. In the Sahel, after a rain event, less than 12 h is necessary to almost fully restore the sand transport potential. Our results suggest that assuming that no sand transport and dust emission occur during the 12 h following the end of a rain event could be a reasonable alternative to existing parameterizations of the influence of soil moisture on the wind erosion threshold, at least for the Sahelian conditions.

Domaines: Sciences de l'environnement; Milieux et Changements globaux

G. Bergametti, J. L Rajot, Caroline Pierre, C. Bouet, B. Marticorena. How long does precipitation inhibit wind erosion in the Sahel?. Geophysical Research Letters, 2016, 43 (12), pp.6643-6649. ⟨10.1002/2016GL069324⟩. ⟨hal-02323084⟩