More Frequent River Avulsions on Deltas Due to Sea-Level Rise

Research Overview

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Recent PhD graduate and Resnick Fellow, Austin Chadwick, is a member of a research team that developed a new numerical model that couples the physics of river flow, sediment transport, riverbed deposition and erosion, and river avulsion processes. The results of this study are summarized in the publication, "Accelerated River Avulsion Frequency on Lowland Deltas Due to Sea-level Rise" and notes that rates of relative sea-level rise on deltas should cause coastal rivers to naturally divert their course, or avulse, more frequently.

Scientific Achievement

We showed modern rates of relative sea-level rise on deltas should cause coastal rivers to naturally divert their course, or avulse, more frequently.

Satellite view of a river avulsion, whereby the river abruptly and catastrophically changed its course to the ocean. This delta is found in East Aceh, Sumatra. Credit: Base image courtesy of Sentinel 2, Vamsi Ganti, and Sam Brooke.

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Satellite view of a river avulsion, whereby the river abruptly and catastrophically changed its course to the ocean. This delta is found in East Aceh, Sumatra. Credit: Base image courtesy of Sentinel 2, Vamsi Ganti, and Sam Brooke.

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Significance and Impact

Results provide a framework to predict delta response to future sea-level rise, which is valuable for planning engineered diversions to nourish deltaic ecosystems and prevent catastrophic flood hazards in coastal megacities.

(L) Satellite view of the Yellow River delta, China. The Yellow River, like other rivers across the globe, repeatedly changes its course on the delta to deposit sediment and build new land. (R) Satellite view of the Mississippi River Delta. On deltas like the Mississippi, sea-level rise will not only cause coastal land loss, but also cause river avulsions to occur more frequently and farther inland than they have historically. Credit: Base images courtesy of Google Earth

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(L) Satellite view of the Yellow River delta, China. The Yellow River, like other rivers across the globe, repeatedly changes its course on the delta to deposit sediment and build new land. (R) Satellite view of the Mississippi River Delta. On deltas like the Mississippi, sea-level rise will not only cause coastal land loss, but also cause river avulsions to occur more frequently and farther inland than they have historically. Credit: Base images courtesy of Google Earth

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Technical Details

• We developed a new numerical model that couples the physics of river flow, sediment transport, riverbed deposition and erosion, and river avulsion processes.
• Model predictions agree with global historical river data.
  

Austin J. Chadwick, Michael P. Lamb, Vamsi Ganti (2020) Accelerated River Avulsion Frequency on Lowland Deltas Due to Sea-Level Rise. Proceedings of the National Academy of Sciences Jul 2020, 117 (30) 17584-17590; DOI: 10.1073/pnas.1912351117

Contact: Michael P. Lamb