Model Characterization of Hydrological and Fluvial Sediment Transport Processes in Present-day and Mid-Pliocene Climate Conditions

The Atacama Desert, known for its hyper-arid climate, occasionally experiences extreme rainfall events, significantly impacting desert hydrology and land-surface evolution. Climate records suggest past interruptions of hyper-aridity, notably during the mid-Pliocene. Understanding hydrological changes during the wet phases is hindered by data scarcity. To address this, we use dynamically downscaled precipitation data from a regional climate model (WRF) and offline Atmospheric and Hydrological-Sediment Modeling Systems (AHMS-SED) to analyze water and sediment discharge during extreme rainfall events under the present-day and mid-Pliocene conditions. Calibration and validation were performed for the Salado River Basin and Paranal clay pan, where relatively more data were recorded. Using AHMS-SED simulations, we explore the long-term land-surface responses to extreme precipitation events and examine the impacts of flash floods on sediment transport under different climate scenarios. This study also provides insights into the effects of extreme rainfall events on desert hydrology and land-surface evolution in a future warmer climate.