Presenters-0715
From CSDMS
CSDMS 2026: Modeling Landscapes in Motion
The lasting imprint of sediment pulses: linking river hazards and landscape evolution
Abstract
Understanding mountain river evolution requires connecting event-scale sediment dynamics to their topographic consequences across timescales. I synthesize observations and models to show how sediment-rich events influence both short-term hazards and longer-term patterns of topographic evolution. Observations and hydraulic analyses show that storm-driven sediment inputs can aggrade channels, reduce conveyance, and modify flood expression well beyond the event itself, effectively conditioning future hazards on prior sediment history rather than water discharge alone. At longer timescales, sediment delivered during extreme events interacts with bedrock channel processes to influence patterns of incision, planation, and terrace formation. Numerical models show that when sediment supply is strongly event-dominated, large precipitation events may suppress rather than enhance bedrock erosion by burying the channel bed. This behavior introduces time lags between forcing and response, complicates interpretations of river incision histories, and links hazard-scale sediment dynamics to the development of persistent topographic features. Together, these results highlight sediment as a key agent linking event-scale disturbances, cascading hazards, and long-term landscape evolution. Disentangling these connections requires models that explicitly represent sediment supply, storage, and transport across scales. Such integrative modeling is essential for predicting how mountain rivers respond to future extremes and for interpreting the geomorphic record left by past events.
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