Michael S. Fenster

New England tidal inlets with special reference to riverine-associated inlet systems

Abstract Tidal inlets along the glaciated coast of New England exhibit a diverse morphology due to widely different physical and geological settings and sediment abundance. Except for the glacial sediment coasts of Cape Cod, Nantucket Island, and Marthas Vineyard, most regions of New England are rocky, and barrier and tidal inlet development is related to isolated glacial and riverine sediment supplies. Inlet-connected bays and marshes encompass many different origins, including drowned river valleys, glacial lake discharge channels, indented bedrock and glacial sediment coasts, kettles, and groundwater sapping channels. Generally, inlet size is correlated to tidal range; the largest inlets (width >300 m) occur along mesotidal coasts, whereas most inlets along microtidal coasts are small (width In spite of their diversity, New England tidal inlets can be grouped into three broad categories based on their morphology, hydrographic regime, and sediment transport characteristics. These classes include the wave-dominated and mixed-energy tidal inlets, and riverine-associated tidal inlets. Wave-dominated inlets tend to occur in microtidal settings and are found primarily in southern New England. They contain flood-tidal deltas of variable morphology and poorly developed or absent ebb-tidal deltas. They have histories of migration, closure, and reopening during storms. Mixed-energy tidal inlets occur mostly along the mesotidal shorelines of central and northern New England. These inlets exhibit well-developed ebb- and flood-tidal deltas. They are backed by extensive marshes and tidal creeks and, in some cases, by a broad system of tidal flats. Riverine-associated tidal inlets coincide with major rivers that have significant freshwater discharge, especially during late winter and early spring. The throat cross-sections are large in comparison to other inlets in New England and are a function of their tidal prism. They contain well-developed subtidal ebb-tidal deltas and variable developed flood-tidal deltas. Ebb-oriented bedforms, grain size, and mineralogical analyses of channel sediments, and hydraulic data have been used to demonstrate that the estuaries are exporting sand to the nearshore, a process that has likely been ongoing since deglaciation. The mechanism for downstream movement of sand in the estuaries is moderate to large spring freshets and major floods when freshwater discharge supplants the saltwater tidal prism. During these periods, there are unidirectional seaward currents in the estuaries that may last for several days or weeks.

Apparent Extinction of the Tiger Beetle, Cicindela hirticollis abrupta (Coleoptera: Carabidae: Cicindelinae)

Abstract The results of this study indicate the historic range of Cicindela hirticollis abrupta Casey was limited to only five sites within the Sacramento Valley of California. Extensive searches within and beyond its historic range along the Feather and Sacramento Rivers in 2001–2004 failed to find any individuals of this tiger beetle and very little suitable habitat. Another tiger beetle, C. o. oregona Dejean, which occurs in a much greater array of water edge habitats, was common at some sites. The cumulative effects from the Oroville and Shasta Dams, including loss and deterioration of sandy edge river habitats and prolonged high water levels, probably caused the extirpation of C. h. abrupta in the late 1980s to early 1990s.

Net ebb sediment transport in a rock-bound, mesotidal estuary during spring-freshet conditions: Kennebec River estuary, Maine

Hydrographic data—obtained concurrently along the 25 km longitudinal axis of the Kennebec River estuary during a 13 h semidiurnal tidal cycle of a spring freshet superimposed on near-perigean spring tides—revealed a strong ebb-current dominance along the length of the estuary. Ebb- current dominance is produced by riverine flow that supplants a substantial part of the flood-tidal prism. In addition, side-scan sonograms showed a suite of large bed forms (1–12 m height) with nearly ubiquitous ebb orientations veneering the estuary bottom. Embayment geometry, salinity, water temperature, discharge, current velocity, and bed-form data all suggest that ebb- velocity asymmetry, set up by seasonal changes in freshwater discharge superimposed on ebb-directed tides, is the most important control on net bed-load sediment transport within this high-latitude, rock- bound estuary. These data augment a model that shows that a freshwater discharge threshold exists for net seaward bed-load sediment transport. The results from this study can be used to refine existing conceptual sedimentologic and morphologic classifications of estuaries.

Coarse-Grained Sediment Transport in Northern New England Estuaries: A Synthesis

Although it is widely stated in the literature that estuarine river mouths are sediment sinks, northern New England estuaries are an exception to this model because they export coarse-grained sediment to the nearshore. The traditional view is that estuaries fill with sediment ranging from mud to gravel derived from fluvial or upland sources as well as from the inner continental shelf and adjacent shorelines. Fluvial sediments are deposited primarily in the inner and central portions of an estuary, although fluvial mud can be deposited in the outer estuary in some tide-dominated systems (e.g. sections of the Gironde River (France), Allen, 1991; Fly River (Papua New Guinea), Harris et al., 1993). The deposition of sediment in the inner and central portions of an estuary is due to the combined influences of a downstream decrease in the riverine current strength and clay flocculation produced by fresh and saltwater mixing. In estuaries having high sediment loads, fluidized mud can be an important component of estuarine sedimentation (Wells, 1983, 1995). Marine sediments enter the outer estuary due to residual, flood-oriented bottom currents and stronger flood than ebb tidal currents. This former flow pattern is caused by the seaward-flowing freshwater advecting the underlying saltwater producing a mass balance deficit of saltwater (Dyer, 1973).

Assessing decadal-scale changes to a giant sand wave field in eastern Long Island Sound

Three digital precision bathymetric data sets spanning 16.1 yr enabled a long-term analysis of the geometric, migration, and volumetric changes to large bedforms in a 1 km2 region of eastern Long Island Sound. Whereas a 1 yr study of sand wave mechanics during 1987 provided indirect evidence of long-term southwestward transport, this study adds a June 2003 data set and conclusively demonstrates a basinward (southwestward) progression of sand waves between 7 and 17 m in height. In addition, the modus operandi of sand wave migration during various temporal scales involves crestal flexing, crestal rotation, and differential migration along the crest. A volumetric analysis suggests that the sand waves are in a waning phase of migration and early stage of preservation as sea level rises into the basin and flood-dominant tidal currents decrease in strength.

Habitat Preference and the Effects of Beach Nourishment on the Federally Threatened Northeastern Beach Tiger Beetle, Cicindela dorsalis dorsalis: Western Shore, Chesapeake Bay, Virginia

Abstract This study examines the habitat preference of the US federally threatened northeastern beach tiger beetle, Cicindela dorsalis dorsalis, and the effect of beach nourishment on existing habitats along two western Chesapeake Bay beaches. Winter Harbor Beach and Smith Point Beach, located approximately 100 km to the north, historically have supported large populations of C. d. dorsalis. Grain size distributions, sediment compaction at two depths, temperature, moisture, and beach width habitat parameters were analyzed by analysis of variance and Tukeys honestly significant difference multiple comparison test and related to the distribution and abundance of C. d. dorsalis. The results from this study indicate that this species prefers beaches at least 6 m wide, with moderately well–sorted sands having a mean grain size of 0.5 to 0.6 mm, and relatively compacted sediment with averages of 69 psi and 110 psi at depths of 10 and 15 cm, respectively. In addition, the two nourishment projects had a positive short-term effect on the beetle habitat despite differences in deposition location. At Smith Point Beach, deposition occurred on top of the subaerial beach with a minimal increase in beach width. At Winter Harbor Beach, nearshore deposition caused a 50-m increase on average in beach width. Within weeks of deposition, adults of C. d. dorsalis rapidly moved onto the nourished sections of both beaches and produced large numbers of larvae. Winter Harbor Beach experienced the greatest increase in beetle numbers, most likely because of the additional habitat created by nearshore deposition. However, continued erosion from natural and anthropogenic sources could produce a chronic threat to productive habitats. These findings will assist coastal engineers and developers in determining effective measures designed to aid both economic and ecologic interests.

Ecotone displacement trends on a highly dynamic barrier Island: Hog Island, Virginia

Aerial photographs, recording 12 positions of the shoreline and vegetation line over a 50-yr period, were used to investigate long-term ecotone displacement trends and the relationship between ecotone displacement and shoreline migration on Hog Island, Virginia. A robust regression modeling technique, originally developed for shoreline trend detection analyses, enabled examination of the direction, magnitude, and timing of changes in long-term ecotone displacement. Measurements were obtained at 277 shore normal transects spaced 50 m apart. The results show that long-term trends in ecotone displacement and shoreline movement are nonlinear for over three-fourths of the Hog Island coast. On average, the shoreline and vegetation line experienced reversals in 1972 and 1974, respectively. Rarely did the ecotones and shorelines move in tandem or synchronously. Concavity tests indicate that most of the shoreline and ecotone are currently moving seaward and the distance between the shoreline and vegetation line is decreasing through time. Evidence exists for a decennial time lag between the reversal of the shoreline and the ecotone and vice versa. The ecotone and shoreline trends apparently correspond to tidal inlet dynamics, individual storm events, storm climate, inherited topography (e.g., dune), and vegetation type.

Effects of off‐highway vehicles on sandy habitat critical to survival of a rare beetle

Recreational activity, including use of off‐highway vehicles, threatens a variety of rare taxa that depend on undisturbed marine beaches, freshwater shorelines, aeolian dunes and other sandy habitats. The endemic Coral Pink Sand Dunes (CPSD) tiger beetle (Cicindela albissima Rumpp) occupies a 300 × 1500 m area within a larger dune field in southwestern Utah. Our objectives were to determine the habitat required by larvae, explain why habitat is so restricted, and to quantify how off‐highway vehicles (OHVs) affected habitat. Macrohabitat characteristics (subsurface moisture, sediment grain size, compaction, vegetation cover) were not different in areas containing high beetle densities compared to those with low. Within the core area containing most beetles, larvae were found primarily in microhabitats with cohesive sand close to the surface. Compaction and moisture provide the cohesive sand required for larvae to maintain burrows during development. Compacted sand, soil moisture and vegetation supporting larval prey were largely absent in heavy OHV‐use areas. Larvae were less abundant within OHV tracks compared to non‐track areas. Apparent survival of larvae experimentally translocated to OHV tracks was lower than that of larvae translocated to non‐OHV areas. Our results show that beetles are restricted to an area where cohesive sand occurs near the surface, interspersed with sufficient vegetation to produce prey. These conditions are localised to an area where dunes migrate at a rate sustaining these conditions. Restricting OHV use from all areas where natural processes create cohesive sand covered with adequate vegetation will minimise extinction probability for the beetle.

Intense Storms Increase the Stability of Tidal Bays

Author Posting.

Robert Dolan (1929–2016)

Dr. Robert Dolan died on 24 April 2016 in Charlottesville, Virginia, at age 87. He was Professor Emeritus at the University of Virginia (UVA). He will be remembered as a pioneer in the field of coastal geomorphology. After serving in the U.S. Navy, Bob earned his B.S. from Southern Oregon College in 1955, his M.S. from Oregon State University in 1957, and his Ph.D. from the Coastal Studies Institute at Louisiana State University in 1965. As part of his dissertation, Bob set up instrumentation on a pier he rented at Nags Head, North Carolina, to measure the impact of storms. Three weeks into this project, the infamous Ash Wednesday storm of 1962 slammed into the U.S. eastern seaboard. An excellent account of Bob’s experience living on the front row of this storm and the impact it had on his life and career can be found in Ribbon of Sand: The Amazing Convergence of the Ocean and the Outer Banks by Alexander and Lazell (2000). In short, living and working through that experience shaped his research direction and career for the next nearly 50 years. I had the great pleasure of working with him for a few short years as his post-doc and on several other projects following the post-doc including a technical review of NASA’s Wallops Island Flight Facility Shoreline Restoration and Infrastructure Protection Program (with Laura Moore and Bob Dean), the Oregon Inlet jetties Environmental Impact Assessment, and a grain-size analysis of the Virginia barrier islands recently published in Sedimentology. Bob took his first and only faculty position at UVA in 1965 where he helped to found the Department of Environmental Sciences in the early 1970s during his tenure as Chair. In the years following, Bob worked with the United States Geological Survey (USGS), National Park Service (NPS), U.S. Army Corps of Engineers, and U.S. Fish and Wildlife Service on many projects, but arguably his most noteworthy were those that took place along the Outer Banks of North Carolina. His work with Harry Lins titled, ‘‘The Outer Banks of North Carolina’’ (Dolan and Lins, 2000) is in its fourth printing. During the 1970s, Bob worked to save the Cape Hatteras lighthouse and Hatteras seashore and wrote a landmark paper on the negative impacts of maintaining sand dunes on beaches. This research ultimately led to a reversal of NPS policy along the Cape Hatteras National Seashore to allow the dunes, built in the 1930s by the Civilian Conservation Corps, to erode naturally. He also recommended mining sand from Cape Point at Cape Hatteras to use for nourishing the beach in front of the Cape Hatteras lighthouse. The borrow site has remained to this day and I affectionately refer to this pond as ‘‘Dolan’s Pond’’ (Figure 1). While the list of his work in this area is quite extensive, I remember him as a liaison and an expert who, among other things, enabled competing interests to develop mutually satisfactory solutions in the debate regarding construction of the Oregon Inlet jetties. Bob also worked as a liaison scientist for the Office of Naval Research (ONR) and lived overseas for two stints during the mid-1980s and mid-1990s assessing ONR coastal and marine research and engineering activities. In the late 1970s and early 1980s, Bob played a major role in advancing the field of shoreline change research with his UVA colleagues Bruce Hayden and Suzette May Kimball among others. He was among the first to develop a shoreline digitizing system when the technology was at its infancy. He then spent many years compiling two large shoreline datasets—COASTS and CEIS—that were used by research groups, coastal land managers, policy makers, and local homeowners to assess the vulnerability of coastal properties and use as a land-use decision making tool. Bob and his research team ultimately used those data to provide technical support for the Federal Emergency Management Agency’s shoreline mapping program Bob Dolan while grab sampling in Oregon Inlet, NC. Photo taken May 2003.