Collaborative Research: Experimental Investigation of Morphodynamic Coupling between River Deltas and Marshes

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Experimental Investigation of Morphodynamic Coupling between River Deltas and MarshesRiver deltas are important to society as population centers and infrastructure hubs for hundreds of millions of people. Most river deltas host vast marshes that are biodiversity hotspots, productive fisheries, effective storm protection, and that capture and store significant amounts of carbon. The processes by which river deltas and marshes grow and collapse as a function of rising sea level and sediment input are well known in isolation. However, there is a fundamental lack of understanding of how marshes and deltas interact. Do feedbacks between marsh and delta dynamics fundamentally influence the behavior of both? The researchers will build laboratory scale deltas subject to controlled environmental conditions that will interact with a newly developed marsh proxy that mimics key marsh properties at a reduced scale. These experiments will help reveal how river deltas and marshes interact over hundred to thousand year timescales under simple conditions, and provide insight into the land loss and subsidence problems that are currently affecting the Mississippi and other global river deltas. The project will broadcast experiments into K-12 classrooms in Louisiana, train a diverse group of researchers at University of Arkansas and Tulane University, and translate results into articles designed for public consumption through social media platforms.The researchers will study how river deltas and marshes interact using physical laboratory experiments that will incorporate a novel marsh proxy. This marsh proxy will be added to deltaic experiments following a rule-based model of sedimentation based on the local elevation of the evolving deposit. For the first time, this will allow them to document how the internal dynamics of deltas are augmented by marshes that cover vast swaths of many delta plains. Through comparison to prior experiments that evolved in the absence of marshes, they will isolate surface dynamics, compactional subsidence patterns, and stratigraphic products of marsh-delta coupling. Quantitative theory developed in this study will aid prediction of marsh and deltas sustainability in the coming decades and enhance ability to interpret their strata for paleo-environmental records. Research will be conducted by a diverse team (in gender, ethnicity, and career stage) including undergraduate and graduate students, and outreach to K-12 students. This project is jointly funded by the Geomorphology and Land-Use Dynamics Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.