Guaranteeing Coastal Wetland Survival under Sea Level Rise through Nature-Based Beneficial-Use Dredged Sediment Placement: A Galveston Bay Living Laboratory
In the absence of adequate natural sediment supply, engineered nature-based features such as submerged sills created from beneficial-use dredged material (BUDM) and placed near marshes have been identified as a means to supply marsh systems and adjacent mudflats with the necessary sediment to sustain productivity and vertical growth to keep up with the pace of sea level rise. The research goal for this project is to quantify the benefits to nearby marsh systems and adjacent coastal communities obtained from strategic subaqueous BUDM placement.
The project (1) measures sedimentation rates at the edge and inside of a target marsh system as a result of nearby sill placement and (2) assesses the ecosystem service benefit in coastal flood risk reduction for coastal communities with and without BUDM support to adjacent marsh systems. To accomplish these objectives, BUDM is placed as a submerged sill near a target marsh in west Galveston Bay, Texas (GBT) in collaboration with the US Army Corps of Engineers (USACE). In-situ measurements of hydrodynamic forcing conditions, sediment dynamics, and bio-physical marsh properties form the data basis for analysis.
Quantifying marsh sediment deposition rates related to submerged BUDM placement is crucial for improvement of existing mixed sediment transport numerical models and marsh evolution models. The physical processes are complex but this unique field data set will provide necessary information to calibrate such models and assess the feasibility of submerged sill placement for marsh restoration. The measurements will also provide the basis for future application of this BUDM placement method to help marshes cope with sea-level rise and improve coastal community resilience. To make this technique widely applicable, it is critical to quantify the derived benefits (physical as well as socio-economic), which will be accomplished based on the GBT test site as part of this project.
Knowledge gained through this project will directly inform USACE design of marsh restoration strategies, and will be available to coastal managers, stakeholders, and the general public through the USACE Engineering with Nature web portal, publications, short-courses, and a new Texas A&M University course curriculum on engineering design with natural marine processes. These efforts help create more resilient coastal communities in light of sea level rise through optimizing low-impact coastal ecosystem restoration techniques and assessing related returns on investment. Improving the understanding and encouraging the use of sustainable, eco-friendly BUDM techniques benefits the State of Texas and society as a whole as rising water levels pose a serious and increasing threat. Stay tuned as this project develops.