Fire (plus) flood (equals) beach: Coastal response to an exceptional river sediment discharge event

Scientific Reports
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Abstract

Wildfire and post-fire rainfall have resounding effects on hillslope processes and sediment yields of mountainous landscapes. Yet, it remains unclear how fire–flood sequences influence downstream coastal littoral systems. It is timely to examine terrestrial–coastal connections because climate change is increasing the frequency, size, and intensity of wildfires, altering precipitation rates, and accelerating sea-level rise; and these factors can be understood as contrasting accretionary and erosive agents for coastal systems. Here we provide new satellite-derived shoreline measurements of Big Sur, California and show how river sediment discharge significantly influenced shoreline positions during the past several decades. A 2016 wildfire followed by record precipitation increased sediment discharge in the Big Sur River and resulted in almost half of the total river sediment load of the past 50 years (~ 2.2 of ~ 4.8 Mt). Roughly 30% of this river sediment was inferred to be littoral-grade sand and was incorporated into the littoral cell, causing the widest beaches in the 37-year satellite record and spreading downcoast over timescales of years. Hence, the impact of fire–flood events on coastal sediment budgets may be substantial, and these impacts may increase with time considering projected intensification of wildfires and extreme rain events under global warming.

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Publication type Article
Publication Subtype Journal Article
Title Fire (plus) flood (equals) beach: Coastal response to an exceptional river sediment discharge event
Series title Scientific Reports
DOI 10.1038/s41598-022-07209-0
Volume 12
Year Published 2022
Language English
Publisher Nature Pulications
Contributing office(s) Pacific Coastal and Marine Science Center
Description 3848, 15 p.
First page 3848
Country United States
State California
Other Geospatial Big Sur watershed
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