Physical Sciences and Mathematics Commons^™

How Old Are Marshes On The East Coast, Usa? Complex Patterns In Wetland Age Within And Among Regions, Anna E. Braswell, James B. Heffernan, Matthew L. Kirwan

VIMS Articles

Sea‐level dynamics, sediment availability, and marine energy are critical drivers of coastal wetland formation and persistence, but their roles as continental‐scale drivers remain unknown. We evaluated the timing and spatial variability of wetland formation from new and existing cores collected along the Atlantic and Gulf coasts of the United States. Most basal peat ages occurred after sea‐level rise slowed (after ~4,000 years before present), but predominance of sea‐level rise studies may skew age estimates toward older sites. Near‐coastal sites tended to be younger, indicating creation of wetlands through basin infilling and overwash events. Age distributions differed among regions, with younger …

Coastal Marsh Degradation Into Ponds Induces Irreversible Elevation Loss Relative To Sea Level In A Microtidal System, Lennert Schepers, Patrick Brennand, Matthew L. Kirwan, Glenn Guntenspergen, Stijn Temmerman

VIMS Articles

Coastal marshes and their valuable ecosystem services are feared to be lost by sea level rise, yet the mechanisms of marsh degradation into ponds and potential recovery are poorly understood. We quantified and analyzed elevations of marsh surfaces and pond bottoms along a marsh loss gradient (Blackwater River, Maryland, USA). Our analyses show that ponds deepen with increasing tidal channel width connecting the ponds to the river, indicating a new feedback mechanism where channels lead to enhanced tidal export of pond bottom material. Pond elevations also decrease with increasing pond size, consistent with previous work identifying a positive feedback between …

Modeling Marsh‐Forest Boundary Transgression In Response To Storms And Sea‐Level Rise, J. Carr, G. Guntenspergen, Matthew L. Kirwan

VIMS Articles

The lateral extent and vertical stability of salt marshes experiencing rising sea levels depend on interacting drivers and feedbacks with potential for nonlinear behaviors. A two‐dimensional transect model was developed to examine changes in marsh and upland forest lateral extent and to explore controls on marsh inland transgression. Model behavior demonstrates limited and abrupt forest retreat with long‐term upland boundary migration rates controlled by slope, sea‐level rise (SLR), high water events, and biotic‐abiotic interactions. For low to moderate upland slopes the landward marsh edge is controlled by the interaction of these inundation events and forest recovery resulting in punctuated transgressive …

Relative Influence Of Antecedent Topography And Sea-Level Rise On Barrier-Island Migration: Sediment Core Data, Justin L. Shawler, Jennifer E. Connell, Bianca Q. Boggs, Christopher J. Hein

Data

No abstract provided.

Sediment Delivery To A Tidal Marsh Platform Is Minimized By Source Decoupling And Flux Convergence, Daniel J. Coleman, Neil K. Ganju, Matthew L. Kirwan

VIMS Articles

Sediment supply is a primary factor in determining marsh response to sea level rise and is typically approximated through high‐resolution measurements of suspended sediment concentrations (SSCs) from adjacent tidal channels. However, understanding sediment transport across the marsh itself remains limited by discontinuous measurements of SSC over individual tidal cycles. Here, we use an array of optical turbidity sensors to build a long‐term, continuous record of SSC across a marsh platform and adjacent tidal channel. We find that channel and marsh concentrations are correlated (i.e., coupled) within tidal cycles but are largely decoupled over longer time scales. We also find that …

Relative Impacts Of Global Changes And Regional Watershed Changes On The Inorganic Carbon Balance Of The Chesapeake Bay, Pierre St-Laurent, Marjorie A.M. Friedrichs, Raymond G. Najjar, Elizabeth Shadwick, Hanquin Tian, Yuanzhi Yao

VIMS Articles

The Chesapeake Bay is a large coastal-plain estuary that has experienced considerable anthropogenic changeover the past century. At the regional scale, land-use change has doubled the nutrient input from rivers and led to an increase in riverine carbon and alkalinity. The bay has also experienced global changes, including the rise of atmospheric temperature and CO2. Here we seek to understand the relative impact of these changes on the inorganic carbon balance of the bay between the early 1900s and the early 2000s. We use a linked land–estuarine–ocean modeling system that includes both inorganic and organic carbon and nitrogen cycling. Sensitivity …

Vims 2019 York River Estuary Data In Support Of: Improved Penetrometer Performance In Stratified Sediment For Cost-Effective Characterization, Monitoring And Management Of Submerged Munitions Sites (Serdp Project: Mr18-1233), Grace M. Massey, Cristin L. Wright, Carl T. Friedrichs, Nina Stark, Dennis Kiptoo

Data

This work complements the efforts by the Virginia Tech Department of Civil & Environmental Engineering in SERDP MR18-1233, as described in the project’s final report (Stark et al, 2020) and in the Master’s thesis by Dennis Kiptoo (Kiptoo, 2020). One of the objectives of the project was to improve calibration of the Bluedrop free fall penetrometer (FFP) with high resolution sampling of a variety of sediment types. To accomplish this, a series of 9 stations over 12 cruises were visited along the York River, an estuary in the Virginia portion of the Chesapeake Bay, and in the Pamunkey River, which …

Vims 2019 Potomac River Estuary Data In Support Of: Improved Penetrometer Performance In Stratified Sediment For Cost-Effective Characterization, Monitoring And Management Of Submerged Munitions Sites (Serdp Project: Mr18-1233), Grace M. Massey, Cristin L. Wright, Carl T. Friedrichs, Nina Stark, Dennis Kiptoo

Data

This work complements the efforts by the Virginia Tech Department of Civil & Environmental Engineering in SERDP MR18-1233, as described in the project’s final report (Stark et al, 2020) and in the Master’s thesis by Dennis Kiptoo (Kiptoo, 2020). Previous work on this project, conducted in the York River during 2018-2918 worked to improve calibration of the Bluedrop free fall penetrometer (FFP) with high resolution sampling of a variety of sediment types (Massey et al, 2020a). Calibration methods developed (Kiptoo, 2020) were used to rapidly identify different sediment types from a grid of 59 Bluedrop PPF stations sampled on the …

Impacts Of Seagrass Dynamics On The Coupled Long‐Term Evolution Of Barrier‐Marsh‐Bay Systems, I.R.B. Reeves, L. J. Moore, E. B. Goldstein, A. B. Murray, Matthew L. Kirwan

VIMS Articles

Seagrass provides a wide range of economically and ecologically valuable ecosystem services, with shoreline erosion control often listed as a key service, but can also alter the sediment dynamics and waves within back‐barrier bays. Here we incorporate seagrass dynamics into an existing barrier‐marsh exploratory model, GEOMBEST++, to examine the coupled interactions of the back‐barrier bay with both adjacent (marsh) and nonadjacent (barrier island) subsystems. While seagrass reduces marsh edge erosion rates and increases progradation rates in many of our 288 model simulations, seagrass surprisingly increases marsh edge erosion rates when sediment export from the back‐barrier basin is negligible because the …

Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers, Kenneth Michael Czapla

Dissertations, Theses, and Masters Projects

Salt marshes provide valuable ecosystem services to human society, but are currently under threat from accelerating sea level rise and nutrient enrichment. Carbon (C) and mineral accumulation allow salt marshes to maintain elevation above sea level and survive. Anthropogenic nitrogen (N) loading is increasing in many salt marshes, causing negative impacts on marsh resilience such as increased decomposition and decreased below-ground production. However, increasing N may also have simultaneous positive effects such as increased primary production and above-ground biomass, surface sediment accretion, and denitrification rates, which remove excess N from coastal waters. Many studies have been conducted to determine the …

The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman

Dissertations, Theses, and Masters Projects

Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration …

Role Of Delta-Front Erosion In Sustaining Salt Marshes Under Sea-Level Rise And Fluvial Sediment Decline, Shi Lun Yang, Xiangxin Luo, Stijn Temmerman, Matthew L. Kirwan, Et Al

VIMS Articles

Accelerating sea-level rise and decreasing riverine sediment supply are widely considered to lead to global losses of deltaic marshes and their valuable ecosystem services. However, little is known about the degree to which the related erosion of the seaward delta front can provide sediments to sustain salt marshes. Here, we present dataf rom the mesomacrotidal Yangtze Delta demonstrating that marshes have continued to accrete vertically and laterally, despite rapid relative sea-level rise (approx.10 mm yr−1) and a > 70% decrease in the Yangtze River sediment supply. Marsh progradation has decelerated at a lower rate than fluvial sediment reduction, suggesting an additional …

Hurricane Sandy Effects On Coastal Marsh Elevation Change, Alice G. Yeates, James B. Grace, Et Al, Scott Lerberg, James C. Lynch, Nichole Maher, J.Patrick Megonigal, W. G. Reay

VIMS Articles

High-magnitude storm events such as Hurricane Sandy are powerful agents of geomorphic change in coastal marshes, potentially altering their surface elevation trajectories. But how do a storm’s impacts vary across a large region spanning a variety of wetland settings and storm exposures and intensities. We determined the short-term impacts of Hurricane Sandy at 223 surface elevation table–marker horizon stations in estuarine marshes located across the northeast region of the United States by comparing post- storm surface elevation change with pre-storm elevation trends. We hypothesized that the storm’s effect on marsh elevation trends would be influenced by position relative to landfall …

Impacts Of Muddy Bed Aggregates On Sediment Transport And Management In The Tidal James River, Va, David W. Perkey, S. Jarrell Smith, Kelsey A. Fall, Grace M. Massey, Carl T. Friedrichs, Emmalynn M. Hicks

VIMS Articles

Aggregation state significantly influences the size, density and transport characteristics of fine sediment. Understanding sediment transport and deposition processes in the nation’s navigable waterways is a primary mission for the US Army Corps of Engineers (USACE), particularly when it comes to infilling of navigation channels. In this study, a newly developed camera system was used to evaluate the aggregation state of eroded sediment from cores collected in the tidal James River, VA. Results showed that bed sediments were composed mostly of mud, but that erosion predominately occurred in the form of aggregates with median sizes 50-270x larger than the disaggregated …

Extraordinary Human Energy Consumption And Resultant Geological Impacts Beginning Around 1950ce Initiated The Proposed Anthropocene Epoch, Jaia Syvitsk, Colin N. Waters, John Day, John D. Milliman, Et Al

VIMS Articles

Growth in fundamental drivers—energy use, economic productivity and population—can provide quantitative indications of the proposed boundary between the Holocene Epoch and the Anthropocene. Human energy expenditure in the Anthropocene, ~22 zetajoules (ZJ),exceeds that across the prior 11,700 years of the Holocene (~14.6 ZJ), largely through combustion of fossil fuels. The global warming effect during the Anthropocene is more thanan order of magnitude greater still. Global human population, their productivity and energy consumption, and most changes impacting the global environment, are highly correlated. This extraordinary outburst of consumption and productivity demonstrates how the Earth System has departed from its Holocene state …

What's In The Muck? Benthic Sediment Characterization And Community Structure, Cristin Wright

Reports

Grades: 9-12 Subjects: Biology | Environmental Science | Oceanography

Sediment classification and grain size can affect the types of organisms that live in the sediment. Some organisms prefer sandier sediment, while others love the fine-grained mud.

In this activity, students will classify sediment samples by grain size and plot their findings on a ternary plot. The students will then further investigate which benthic organisms live in the different sediments and which may be more resilient to a change in sediment classification.

Filling In The Gaps: Applications Of Deep Learning, Satellite Imagery, And High Performance Computing For The Estimation And Distribution Of Geospatial Data, Seth Goodman

Dissertations, Theses, and Masters Projects

Many regions around the world suffer from a lack of authoritatively-collected data on factors critical to understanding human well-being. This challenges our ability to understand the progress society is making towards reducing poverty, improving lifespans, or otherwise improving livelihoods. A growing body of research is exploring how deep learning algorithms can be used to produce novel estimates of sparse development data, and how access to such data can impact development efforts. This dissertation contributes to this literature in three parts. First, using Landsat 8 satellite imagery and data from the Armed Conflict Location & Event Data Project, convolutional neural networks …