Geomorphology Commons^™

Field Validation Of Dem And Gis Derived Longitudinal Stream Profiles, Kathryn Schroeder, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

Longitudinal stream profiles provide valuable information concerning geomorphic features and energy states in a stream. Traditionally, stream profiles have been generated by field surveying or topographic map analysis. The continued growth of digital data and Geographic Information Systems (GISs) provide another method by which to achieve stream profile generation. This work examines the effectiveness of digital data, digital elevation models (DEM), and GIS to construct stream profiles. To determine the most effective and accurate data for profile generation, profiles were created using 1-meter (1-m) and 3-meter (3-m) DEMs developed from LiDAR data. Additionally, stream profiles were created from unfilled DEMs …

Longitudinal Profile And Sediment Mobility As Geomorphic Tools To Interpret The History Of A Fluviokarst Stream System, John Woodside, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

The complex drainage systems within karst settings can result in atypical longitudinal profiles. Features, such as cave entrances, can be expressed as anomalous ‘bumps’ in the longitudinal profile of a stream if downcutting has continued upstream of the area in which the water is pirated to the subsurface. Horn Hollow, a fluviokarst valley located in Carter Caves State Park Resort in northeastern Kentucky, was examined for these types of features. The objectives of this study were to determine if sediment mobility can be used as a proxy for anomalous areas along the profile of the valley and if detailed cross-sections …

Exhumation Of The Southern Sierra Nevada–Eastern Tehachapi Mountains Constrained By Low-Temperature Thermochronology: Implications For The Initiation Of The Garlock Fault, Ann Blythe, N Longinotti

Ann Blythe

New apatite and zircon fission-track and apatite (U-Th)/He data from nine samples collected on a north-south transect across the southern Sierra Nevada–eastern Tehachapi Mountains constrain the cooling and exhumation history over the past ∼70 m.y. The four northernmost samples yielded zircon and apatite fission-track ages of ca. 70 Ma, indicating rapid cooling from ∼250 °C to <60 °C (6–8 km of exhumation) at that time. Four of the five southernmost samples yielded slightly younger zircon fission-track ages (57–46 Ma) and apatite fission-track ages (21–18 Ma); the fifth southern sample (from a lower elevation) yielded an apatite fission-track age of ca. 11 Ma. Eight of the nine samples yielded apatite (U-Th)/He ages; these ranged from 60 to 9 Ma, with the youngest ages from the southernmost samples. Inverse thermal history models developed from the data reveal two major stages of cooling for the area, with an initial major cooling event ending at ca. 70 Ma, followed by 50 m.y. of thermal stasis and a second major cooling event beginning at 20 Ma and continuing to the present. The data are consistent with northward-directed tilting and exhumation beginning at 20 Ma, probably as the result of north-south extension in the Mojave Desert on an early strand of the Garlock fault with down-to-the-south offset. A third minor phase of rapid exhumation beginning at ca. 10 Ma is suggested by the data; this may indicate the beginning of left-lateral slip on the Garlock fault.

Meteoric 10Be, FeD, And Clay In Critical Zone Soils, Front Range, Colorado, Cianna Wyshnytzky, James Mccarthy

Cianna E Wyshnytzky

The critical zone is the zone within which meteoric water, atmospheric gases, soil, and bedrock interact, encompassing the zone of soil formation (Anderson et al., 2007). The concentrations of various pedogenic compounds at a given location indicate the degree of weathering that has taken place in the Critical Zone. Among the products of chemical weathering are secondary phyllosilicate minerals (clays) and iron (Birkeland, 1999). At stable sites, chronosequence studies have shown that the amount of pedogenic iron oxide and clay increase as soils become older (McFadden and Hendricks, 1985).

Meteoric ¹⁰Be is a cosmogenic nuclide produced from oxygen and nitrogen …

Holocene Sediment Distribution On The Inner Continental Shelf Of Northeastern South Carolina: Implications For The Regional Sediment Budget And Long-Term Shoreline Response, Jenny Denny, William Schwab, Wayne Baldwain, Walter Barnhadt, Paul Gayes, Robert Morton, John Warner, Neil Driscoll, George Voulgaris

George Voulgaris

High-resolution geophysical and sediment sampling surveys were conducted offshore of the Grand Strand, South Carolina to define the shallow geologic framework of the inner shelf. Results are used to identify and map Holocene sediment deposits, infer sediment transport pathways, and discuss implications for the regional coastal sediment budget.

The thickest deposits of Holocene sediment observed on the inner shelf form shoal complexes composed of moderately sorted fine sand, which are primarily located offshore of modern tidal inlets. These shoal deposits contain ∼67 M m3 of sediment, approximately 96% of Holocene sediment stored on the inner shelf. Due to the lack …

Evaluation Of Beach Nourishment Evolution Models Using Data From Two South Carolina Beaches: Folly Beach And Hunting Island, Sc, Usa, Harry Weathers, George Voulgaris

George Voulgaris

Beach nourishment is a common method used for mitigating coastal erosion. However, it is also a costly undertaking and requires an appropriate cost-to-benefit analysis. Although the costs can be estimated relatively easily, the benefits are directly related to the life expectancy of the proposed project. With this in mind, three existing beach replenishment time-evolution models (the Linear Erosion, the Verhagen, and the One-Line models) were compared for their ability to represent data from two beach nourishment projects that have taken place in South Carolina, USA, at Folly Beach and Hunting Island. Another newly introduced model that combines the One-Line model …

Introduction And Tribute, George Voulgaris, Timothy Kana, Jacqueline Mitchell

George Voulgaris

No abstract provided.

Radon As An Indicator Of Limited Cross-Shelf Mixing Of Submarine Groundwater Discharge Along An Open Ocean Beach In The South Atlantic Bight During Observed Hypoxia, Clayton Mccoy, Richard Viso, Richard Peterson, Susan Libes, Brent Lewis, John Ledoux, George Voulgaris, Erik Smith, Denise Sanger

George Voulgaris

Amongst other ocean state parameters, the development of a wave measurement program was supported as part of the Southeast U.S. Atlantic Coastal Ocean Observing System (SEACOOS). The program focused on supporting nearshore wave measurements using both cabled and autonomous systems but also examined the feasibility of using HF Radar systems for remote estimation of wave parameters. The nearshore stations have provided a significant database on directional wave climate for a number of nearshore locations in the region that provide valuable information to coastal engineers and managers for sustainable development along the coast of the southeastern United States. The ability of …

Wind-Speed Inversion From Hf Radar First-Order Backscatter Signal, W Shen, Klaus-Werner Gurgel, George Voulgaris, Thomas Schlick, D Stammer

George Voulgaris

Land-based high-frequency (HF) radars have the unique capability of continuously monitoring ocean surface environments at ranges up to 200 km off the coast. They provide reliable data on ocean surface currents and under slightly stricter conditions can also give information on ocean waves. Although extraction of wind direction is possible, estimation of wind speed poses a challenge. Existing methods estimate wind speed indirectly from the radar derived ocean wave spectrum, which is estimated from the secondorder sidebands of the radar Doppler spectrum. The latter is extracted at shorter ranges compared with the first-order signal, thus limiting the method to short …

Estimating The Timing Of Cave Level Development With Gis, Brianne Jacoby, Eric Peterson, Toby Dogwiler, John Kostelnicj

Eric Wade Peterson

Identifying cave levels provides insight into cave development and climatic changes that have affected a karst system over time. Cosmogenic dating has been used to interpret levels in Mammoth Cave and the Cumberland Plateau. This absolute dating technique has proven successful in determining cave paleoclimates and regional geomorphic history, but is expensive. The study presented here is a preliminary method to cosmogenic dating that can outline a region’s speleogenesis using a Geographic Information System (GIS) and published denudation rates. The Carter Cave system in northeastern Kentucky is within the karst landscape found along the western edge of the Appalachians and …

A Case History Of The Science And Management Collaboration In Understanding Hypoxia Events In Long Bay, South Carolina, Usa., Denise Sanger, Debra Hernandez, Susan Libes, George Voulgaris, Braxton Davis, Erik Smith, Rebecca Shufford, Dwayne Porter, Eric Koepfler, Joseph Bennet

George Voulgaris

Communication of knowledge between the scientific and management communities is a difficult process complicated by the distinctive nature of professional career goals of scientists and decision-makers. This article provides a case history highlighting a collaboration between the science and management communities that resulted from a response to a 2004 hypoxia, or low dissolved oxygen, event in Long Bay, off Myrtle Beach, South Carolina. A working group of scientists and decision-makers was established at the time of the event and has continued to interact to develop a firm understanding of the drivers responsible for hypoxia formation in Long Bay. Several factors …

Assessing The Impact Of An Organic Restoration Structure On Boat Wake Energy, Jean Ellis, Douglas Sherman, Bernard Bauer, Jeffrey Hart

Jean Taylor Ellis

No abstract provided.

Depth Compensation For Pressure Transducer Measurements Of Boat Wakes, Jean Ellis, Douglas Sherman, Bernard Bauer

Jean Taylor Ellis

No abstract provided.

Retention Of Beach Sands By Dams And Debris Basins In Southern California, Douglas Sherman, Kamron Barron, Jean Ellis

Jean Taylor Ellis

No abstract provided.

Wave Transformation Across A Rock Platform, Belinho, Portugal, Eugene Farrell, Helena Granja, Lorenzo Cappietti, Jean Ellis, Bailiang Li, Douglas Sherman

Jean Taylor Ellis

No abstract provided.

Exploring The Persistence Of Sorted Bedforms On The Inner-Shelf Of Wrightsville Beach, North Carolina, Benjamin Gutierez, George Voulgaris, Robert Thieler

George Voulgaris

Geological studies offshore of Wrightsville Beach, North Carolina reveal subtle large-scale regions of coarse sand with gravel and shell hash (widths between 100 and 200 m and negative relief of ∼1 m) that trend obliquely to the coast. It was previously suggested that these regions serve as conduits for sand exchange between the shoreface and inner shelf during storm-associated downwelling. Consequently they were classified as rippled scour depressions. More recently, the role of alongshore flows and self-organization as a result of inhibited settling of fine sand has been discussed. In this study, 45 days of near-bed current measurements were analyzed …

Effect Of Channel Bifurcation On Residual Estuarine Circulation: Winyah Bay, South Carolina, Yong Kim, George Voulgaris

George Voulgaris

The residual circulation pattern of Winyah Bay, the fourth largest estuary on the eastern coast of the US, is examined using stationary and shipborne current measurements during periods of low freshwater discharge. The estuary has a complex morphology with a single channel and narrow banks at the river entrance and the bay mouth, and a bifurcated channel system (main and western channels, respectively) in the middle part that appears to affect the residual circulation. Overall, the upper (single channel morphology) and middle (dual-channel morphology) parts of the estuary exhibit a baroclinic residual circulation. The presence of bifurcated channels in the …

Internal Waves Revealed By Synthetic Aperture Radar (Sar) Imagery In The Vicinity Of The Eastern Cretan Arc Straits (Eastern Mediterranean), Adonis Velegrakis, E. Oikonomou, A. Theocharis, M Collins, H Kontoyannis, V Papadopoulos, George Voulgaris, T. Wells, E. Balopoulos

George Voulgaris

Internal waves have been detected on ERS-1 SAR images obtained during late summer over the eastern Cretan Straits, an area characterised by complex regional physiography, bottom topography, flow regime and stratification patterns of the upper part of the water column. Analysis of the imaged characteristics of the internal waves has revealed a strong diversity in form, propagation direction and type of sea surface modulation, which indicates various mechanisms of generation. Analysis of the currents recorded over the area shows that, although semi-diurnal tidal currents are present, these are of low magnitude in comparison with the overall flow and, therefore, tidal …

The In Situ Passive Acoustic Measurement Of Shingle Movement Under Waves And Currents: Instrument (Tosca) Development And Preliminary Results, George Voulgaris, Michael Wilkin, Michael Collins

George Voulgaris

An instrumented platform (TOSCA) is described for monitoring coarse-grained sediment transport in high (wave and tidal) energy environments. The system consists of a number of sensors which measure: instantaneous current velocities at three levels; sea surface elevation; and self-generated noise (SGN) caused by intercollision of particles in transit. SGN is related to transport rates, on the basis of laboratory calibration; this, in turn, allows a correlation with simultaneous near-bed shear stress to be established. During the field measurements, PC-based real-time data transmission is realised through the use of a (buoyed) radio telemetry system.

TOSCA has been deployed in eastern Christchurch …