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Rock Strength Along A Fluvial Transect Of The Colorado Plateau - Quantifying A Fundamental Control On Geomorphology, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

Bedrock strength is a key parameter that influences slope stability, landscape erosion, and fluvial incision. Yet, it is often ignored or indirectly constrained in studies of landscape evolution, as with the K erodibility parameter in stream-power models. Empirical datasets of rock strength suited to address geomorphic questions are rare, in part because of the difficulty in measuring those rocks at Earth's surface that are heterolithic, weak, or poorly exposed. Here we present a large dataset of measured bedrock strength organized by rock units exposed along the length of the trunk Green–Colorado River through the iconic Colorado Plateau of the western …

A 70 Year History Of Coastal Dune Migration And Beach Erosion Along The Southern Shore Of Lake Michigan, Zoran Kilibarda, Craig Shillinglaw

Zoran Kilibarda

A study of aerial photographs from the Indiana Dunes National Lakeshore (adjacent to Michigan City, Indiana, United States of America) revealed that from 1938 to 2008 the Lakeshore’s Mount Baldy dune advanced inland 135 m, at an average rate of 1.9 m/year, while the beach north of the dune receded 98 m, at an average rate of 1.4 m/year. The highest rates of Mount Baldy dune movement (3.3 m/year) occurred concurrently (1965–1973) with highest rates of beach erosion (7.2 m/year). The lowest rates of Mount Baldy dune movement (0.3 m/year) occurred in 1958–1965 period. The highest rates of beach accretion …

The Effects Of Surface Water Velocity On Hyporheic Interchange, Timothy Sickbert, Eric Wade Peterson

Eric Wade Peterson

When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream and the subsurface. In the case of moving water, it is invalid to ignore velocity and to assume that stage equals the net downward pressure on the streambed. The Bernoulli equation describes the distribution of energy within flowing fluids and implies that net pressure decreases as a function of velocity, i.e., the Venturi Effect, which sufficiently reduces the pressure on the streambed to create the appearance of a …

Bedrock Strength And River Morphology Datasets For The Colorado River System, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

There has been renewed debate over the mechanisms and timing of both uplift and erosion in the Interior West. Yet, in order to understand the region’s long-term landscape evolution and patterns of topography a third factor of bedrock properties must be considered. We are completing a large dataset of bedrock strength and exploring it in the context of reach-scale topographic metrics for the upper Colorado River system. Included are rock-strength measures such as laboratory tensile strength, Schmidt-hammer compressive strength, approximate shale proportion, and Selby rock mass strength classification. To estimate the strength of units too incompetent to test directly, such …

Geomorphic Analysis Of Tidal Creek Networks, Karyn Novakowski, Raymond Torres, L Gardner, George Voulgaris

George Voulgaris

The purpose of this study is to determine if concepts in terrestrial channel network analysis provide insight on intertidal creek network development and to present new metrics for their analysis. We delineated creek network geometry using high-resolution digital images of intertidal marsh near Georgetown, South Carolina. Analyses reveal that intertidal creek networks may be topologically random. Length-area relationships suggest that salt marsh and terrestrial networks have similar scaling properties, although the marsh networks are more elongate than terrestrial networks. To account for recurrent water exchange between creek basins at high tide, we propose that the landscape unit of geomorphic analyses …

Bedrock Strength And River Metrics: Spatial And Statistical Correlations On The Incision Of The Colorado Plateau, Southwest Usa, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

Physiographic Factors Defining The Snake River Valley Ava; Beyond "Vin De Idaho", David Wilkins, Virginia Gillerman, Krista Shellie, Ron Bitner, Gregory Jones

David E. Wilkins

Beginning in 1971 with the first plantings of wine grapes, the wine and wine grape industry in southwest Idaho have grown to become significant contributors to the state economy with an annual impact of $75 million (Bierle et al., 2008). With around 1600 acres under cultivation in 50 vineyards producing at least 24 varietals (as of 2007), wine grapes are the state's second largest fruit crop in acreage, with the majority of the crop (USDA, 2008) being produced in the western Snake River Plain of southwestern Idaho and eastern Oregon. In April, 2007, a 21,400 sq. km area in this …

Morphology And Origin Of The Fair Oaks Dunes In Nw Indiana, Usa, Zoran Kilibarda, Joseph Blockland

Zoran Kilibarda

The Fair Oaks Dunes (FOD) of NW Indiana, USA is a large (~4500 km2) inland dune field associated with the late Wisconsin deglaciation of the Laurentide Ice Sheet. Meltwaters released by the Michigan, Saginaw, and Huron–Erie lobes transported fluvioglacial sediment through the Kankakee and Tippecanoe Valleys and their tributaries. The texture and composition of the sand in the FOD suggest a Saginaw Lobe origin of sediment with some Huron–Erie Lobe sediment. Sub-mature sand with sub-angular grains and a large feldspar content suggests relatively short distance of transport during two or possibly three dune-building and dune reworking events. We propose a …

Identifying The Stream Erosion Potential Of Cave Levels In Carter Cave State Resort Park, Kentucky, Usa, Eric Peterson, Brianne Jacoby, Toby Dogwiler

Eric Wade Peterson

Cave levels, passages found at similar elevations and formed during the same constant stream base level event, reveal information about paleoclimates and karst geomorphology. The investigation presented here examines how Stream Power Index (SPI) relates to cave levels. The study area, Carter Caves State Resort Park (CCSRP), is a fluviokarst system in northeastern Kentucky containing multiple cave levels. SPI deter-mines the erosive power overland flow based on the assumption that flow accumulation and slope are proportional to potential for sediment entrainment. Part of this digital terrain analysis requires the creation of a flow accumulation raster from a digital elevation model …