A shallow compaction model for Holocene Mississippi Delta sediments
C. Zoccarato, P. Teatini
Dept. of Civil, Environmental and Architectural Engineering, University of Padova, Italy
T. Tornqvist, J. G. Bridgeman<
Dept. of Earth and Environmental Sciences, Tulane University, New Orleans, Louisiana, USA
ABSTRACT
The extensive loss of land elevation and the consequent exposure to flood hazards are seriously
threatening the long-term survival of the Mississippi Delta. Shallow compaction of the top soil
is one of the major components contributing to the relative sea level rise. In the last decades,
more subsidence measurements have become available and recent studies demonstrate that compaction
of Holocene strata is dominant. Here we propose a novel application aimed at modeling the present-day
shallow compaction due to consolidation processes in the top soil. Soil compaction is properly
computed and accounts for the large soil grain motion and the delayed dissipation of pore-water
overpressure. The grain motion is described by means of a Lagrangian approach with an adaptive
mesh where the grid nodes follows the accretion/compaction processes. Model calibration is
obtained from stratigraphic and geochrology information collected at the Myrtle Grove Subsidence
Superstation, where a nearly 40 m-deep sediment core that penetrates the entire Holocene succession
allows testing model results over long (millennial) timescales. Model validation with available
observations from rod surface-elevation table - marker horizon (RSET-MH) data enables the model
to predict future scenarios.
