Stratigraphic controls on subsidence in the Mississippi Delta

Wetlands provide the first line of defense for coastal and estuarine populations and environments from damaging storm surges. While multi-billion-dollar projects are planned to ameliorate rapid wetland loss and flood risk in Louisiana, USA, the mechanics of the Mississippi Delta and its underlying architecture are not well constrained in the context of these strategies. Among these, land-surface-elevation loss through subsidence is primary in assessing the land-building potential of river diversions aiming to deliver sediment to wetlands.

This project uses a combination of instrumental (e.g., geophysical surveys), historical (e.g., maps), and geochronologic (e.g., OSL) tools to determine the subsidence risk of diversion receiving basins as it relates to the heterogeneous subsurface lithology that is common across the delta. We also assess the benefit diversions offer to global climate through carbon sequestration. The research aims to product: (i) Quantified differential vertical accretion and subsidence rates within three depositional environments common in the Mississippi Delta: marsh, local waterbody (bay, lake), and (paleo)channel. (ii) A novel subsidence map relating subsidence rates to underlying lithologies in and near the Mid-Barataria Bay Diversion receiving basin. (iii) New estimates of carbon sequestration by deltaic depositional environments.