Fluvial‐Aeolian Interactions and Landscape Recovery After Extreme Events: A Death Valley Dune Field After Hurricane Hilary

Abstract

In arid landscapes, wind drives slow, persistent sediment transport year after year, while rare floods can reshape the landscape in a matter of hours. Recent record‐breaking rainfall, following Hurricane Hilary in August 2023, caused widespread flooding, erosion, and deposition in the Mesquite Flat Dune Field, extending across Death Valley, California. In this work, we study the interaction between fluvial and aeolian sediment transport associated with this extreme event, specifically focusing on landscape recovery. Using repeat satellite images, field observations, and terrestrial LiDAR, we quantify flood depths, sediment volumes, and the pace of landscape recovery. Floodwaters penetrated more than one km into the dune‐field interior, resulting in interdune ponds of standing water up to 3.9 m in depth. As the water receded, deposition of fine sediment from the turbid waters left millimeter‐to‐centimeter thick mud drapes on the dunes and interdunes, armoring the surface from aeolian erosion. Where fluvial erosion removed entire dunes, nascent dunes re‐formed in less than 2 years. Repeat field observations show that fluvial mud deposits were rapidly eroded by aeolian abrasion and unlikely to contribute to the rock record except where they were rapidly buried by dune migration.