Biogeosciences Editors' Highlights

Coastal Sediment Deficit Appears Smaller Than Previously Thought

With a deficit of sediment needed to compensate for relative sea level rise, a new study demonstrates that organic material cannot be ignored in evaluating mass and volume accumulation rates.

Source: Journal of Geophysical Research: Earth Surface


Sea level rise jeopardizes deltas and coastal plains, and this is aggravated by subsidence. Both sea level rise and subsidence may partly be compensated for by the accumulation of sediment and other material. Scientists and engineers have predominantly focused on sediment from the river in this context, which often dominates Holocene river delta deposits.

Sanks et al. [2020] analyzed 24-centimeter-deep sediment cores from 391 sites in coastal Louisiana, demonstrating that the often-ignored organic fraction of recently accreted material can be substantial, even on a regional scale. Across coastal Louisiana, organic material accounted for as much as 30 per cent of all volume accumulation, and the associated small bulk densities found in surface sediments significantly offset large subsidence rates. Consequently, the deficit of sediment needed to compensate for relative sea level rise is smaller than previously thought.

This study is based on a globally unprecedented dataset and is likely to trigger widespread debate given that its findings differ substantially from previous studies.

Citation: Sanks, K. M., Shaw, J. B., & Naithani, K. [2020]. Field‐based estimate of the sediment deficit in coastal Louisiana. Journal of Geophysical Research: Earth Surface, 125, e2019JF005389.

—Ton A. J. F. Hoitink, Editor, JGR: Earth Surface

Text © 2020. The authors. CC BY-NC-ND 3.0
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