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Storm-induced precipitation variability control of long-term erosion


IPGP - Îlot Cuvier


Séminaires thème Système Terre

Visio Zoom

Éric Gayer

Université de Paris - IPGP

Erosion is often treated as a continuous process, yet it occurs through discrete events such as floods and landslides of variable magnitude and periodicity. It has also long been expected to be strongly dependent on precipitation, however, the influence of temporal rainfall variability upon long-term evolution of landscapes remains unclear. In this project we report high erosion rates (0.8 to ~10 mm yr-1 over ~70 ka) estimated from paleovolcanic reconstructions across a steep rainfall gradient on Reunion Island, which show that long-term erosion rates are influenced by the cyclone-induced variability of precipitation. Geostatistical analysis of 30 years of daily rainfall records reveals that erosion rates are high where the local climate is the driest and where the difference in intensity between extreme rainfall events and prevailing precipitation is the strongest. This implies that the intrinsic variability of precipitation impacts landscape evolution not only through extreme meteorological events, but also through background rainfall-induced parameters such as humidity and dryness, which modulate the erosion threshold of the Earth's Critical Zone. Zoom link: