Numerical simulations of Holocene salt-marsh dynamics under the hypothesis of large soil deformations

• Published in: Advances in water resources 2017-12, Vol.110, p.107-119
• Main Authors: Zoccarato, C., Teatini, P.
• Format: Article
• Language: English
• Subjects: Accretion; Adaptive mesh; Compaction; Computer simulation; Consolidation; Deformation mechanisms; Deposition; Dynamics; Finite element method; Frameworks; Geomechanics; Grain; Groundwater; Groundwater flow; Holocene; Holocene deposition; Interactions; Intertidal salt marshes; Iron; Large soil compaction; Linearity; Mathematical models; Modelling; Numerical experiments; Numerical modeling; Numerical models; Numerical simulations; Overpressure; Porous media; Salt marshes; Saltmarshes; Sea level; Sea level rise; Sedimentation; Sedimentation & deposition; Sedimentation rates; Simulators; Soil; Soil compaction; Soil dynamics; Soil permeability; Soil properties; Two dimensional flow; Two dimensional models; Wetlands
• ISSN: 0309-1708; 1872-9657
• DOI: 10.1016/j.advwatres.2017.10.006

•A numerical model for the long-term marsh accretion and compaction is proposed.•A 2D groundwater flow simulator is coupled to a 1D vertical geomechanical module.•The mechanical compaction highly influences the marsh vertical dynamics. Salt marshes are vulnerable environments hosting complex interactions between physical and biological processes. The prediction of the elevation dynamics of a salt-marsh platform is crucial to forecast its future behavior under potential changing scenarios. An original finite-element (FE) numerical model accounting for the long-term marsh accretion and compaction linked to relative sea level rise is proposed. The accretion term considers the material sedimentation over the marsh surface, whereas the compaction reflects the progressive consolidation of the porous medium under the increasing load of the overlying younger deposits. The modeling approach is based on a 2D groundwater flow simulator coupled to a 1D vertical geomechanical module, where the soil properties may vary with the effective intergranular stress. The model takes also into account the geometric non-linearity arising from the consideration of large solid grain movements by using a Lagrangian approach with an adaptive FE mesh. The numerical experiments show the potentiality of the proposed 2D model, which consistently integrates in modeling framework the behavior of spatially distributed model parameters. High sedimentation rates and low permeabilities largely impact on the mechanism of soil compaction following the overpressure dissipation.