Identifier

etd-05302017-164350

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Over 25% of Mississippi delta (MRDP) wetlands were lost over the past century. There is currently a major effort to restore the MRDP focused on a 50-year time horizon, a period during which the energy system and climate will change dramatically. I modeled hydraulic dredging to sustain marsh from 2016-2066 and 2016-2100 under a range of scenarios for sea level rise, energy price, and management regimes. A marsh elevation model was calibrated to data from MRDP marshes. I developed a model to simulate dredging costs based on the price of crude oil and a project efficiency factor. Crude oil prices were projected using forecasts from global energy models. The costs to sustain marsh between 2016 and 2100 changed from $128,000 ha-1 in the no change scenario to ~$1,010,000 ha-1 in the worst-case scenario in sea level rise and energy price, an ~8-fold increase. Increasing suspended sediment load raised created marsh lifespan and decreased long term dredging costs. Created marsh lifespan changed nonlinearly with dredging fill elevation and suspended sediment level. Costs and benefits of marsh creation can be optimized by adjusting dredging fill elevations based on the local sediment regime. Regardless of management scenario, sustaining the MRDP with hydraulic dredging suffered declining returns on investment due to the convergence of energy and climate. Marsh creation will likely become unaffordable in the mid to late 21st century, especially if river sediment diversions are not constructed before 2030. Planners must take into consideration coupled energy and climate scenarios for long-term risk assessments and adjust restoration goals accordingly.

Date

2017

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

D'Elia, Christopher

DOI

10.31390/gradschool_theses.4607

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