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At least 37 records · Page 2Linked to original sources
USGS2021

Impacts of sediment removal from and placement in coastal barrier island systems

Executive Summary On June 24, 2019, Congressman Raul Grijalva of Arizona, Chair of the House Committee on Natural Resources, sent a letter to the directors of the U.S. Fish and Wildlife Service and the U.S. Geological Survey to request their assistance in answering questions regarding coastal sediment resource management within the Coastal Barrier Resources System as defined by the Coastal Barrier Resources Act (Public Law 97–348; 96 Stat. 1653; 16 U.S.C. 3501 et seq.). For the purposes of this response, coastal sediment resource management refers to the removal of sediment from one part of a barrier island system for placement in another part of the coastal system, for either hazard mitigation (for example, erosion or flood control) or coastal restoration (for example, expansion or restoration of beach, dune, and [or] marsh habitats). The specific topics of concern are as follows (paraphrased from Congressman Grijalva’s letter): 1. Disruption of coastal sediment supply resulting from sediment removal and placement, including the replenishment rate of removed sediments and impacts to other components of the barrier island system (discussed in sec. 3). 2. Physical and biological impacts of sediment removal and placement on benthic habitats (discussed in sec. 4). 3. Impacts of sediment removal and placement on fish and other marine species (discussed in sec. 5). 4. Changes in migratory bird nesting and foraging habitats resulting from sediment removal and placement (discussed in sec. 6). 5. Long-term impacts of sediment removal and placement on physical coastal resiliency (discussed in sec. 7).

Open-File Report↗
USGS2016

Erosional and depositional history of the Atlantic passive margin as recorded in detrital zircon fission-track ages and lithic detritus in Atlantic Coastal plain sediments

Comparison of fission-track (FT) ages of detrital zircons recovered from Atlantic Coastal Plain sediments to FT ages of zircons from bedrock in source terranes in the Appalachians provides a key to understanding the provenance of the sediments and, in turn, the erosional and depositional history of the Atlantic passive margin. In Appalachian source terranes, the oldest zircon fission-track (ZFT) ages from bedrock in the western Appalachians (defined for this paper as the Appalachian Plateau, Valley and Ridge, and far western Blue Ridge) are notably older than the oldest ages from bedrock in the eastern Appalachians (Piedmont and main part of the Blue Ridge). The age difference is seen both in ZFT sample ages and in individual zircon grain ages and reflects differences in the thermotectonic history of the rocks. In the east, ZFT data indicate that the rocks cooled from temperatures high enough to partially or totally reset ZFT ages during the Paleozoic and (or) Mesozoic. The majority of the rocks are interpreted to have cooled through the ZFT closure temperature (∼235 °C) at various times during the late Paleozoic Alleghanian orogeny. In contrast, most of the rocks sampled in the western Appalachians have never been heated to temperatures high enough to totally reset their ZFT ages. Reflecting their contrasting thermotectonic histories, nearly 80 percent of the sampled western rocks yield one or more zircon grains with very old FT ages, in excess of 800 Ma; zircon grains yielding FT ages this old have not been found in rocks in the Piedmont and main part of the Blue Ridge. The ZFT data suggest that the asymmetry of zircon ages of exposed bedrock in the eastern and western Appalachians was in evidence by no later than the Early Cretaceous and probably by the Late Triassic. Detrital zircon suites from sands collected in the Atlantic Coastal Plain provide a record of detritus eroded from source terranes in the Appalachians during the Mesozoic and Cenozoic. In Virginia and Maryland, sands of Early Cretaceous through late early Oligocene age do not yield any old zircons comparable in age to the old zircons found in bedrock in the western Appalachians. Very old zircons yielding FT ages >800 Ma are only encountered in Coastal Plain sands of middle early Miocene and younger age. Miocene and younger fluvial-deltaic deposits associated with the major mid-Atlantic Coastal Plain rivers that now head in the western Appalachians (the Hudson, Delaware, Susquehanna, Potomac, James, and Roanoke) contain abundant clasts of fossiliferous chert and quartzite and other distinctive rock types derived from Paleozoic rocks of the western Appalachians. These distinctive clasts have not been reported in older Coastal Plain sediments. The ZFT and lithic detritus data indicate that the drainage divide for one or more east-flowing mid-Atlantic rivers migrated west into the western Appalachians, and the river(s) began transporting western Appalachian detritus to the Atlantic Coastal Plain, sometime between the late early Oligocene and middle early Miocene. By no later than late middle Miocene most if not all of the major rivers that now head west of the Blue Ridge were transporting western Appalachian detritus to the Coastal Plain. Prior to the drainage divide migrating into the western Appalachians, the ZFT data are consistent with the dominant source of Atlantic Coastal Plain sediments being detritus from the Piedmont and main part of the Blue Ridge, with possible input from distant volcanic sources. The ZFT data suggest that the rapid increase in the rate of siliciclastic sediment accumulation in middle Atlantic margin offshore basins that peaked in the middle Miocene and produced almost 30 percent of the total volume of post-rift siliciclastic sediments in the offshore basins began in the early Miocene when Atlantic river(s) gained access to the relatively easily eroded Paleozoic sedimentary rocks of the western Appalachians.

American Journal of Science↗
USGS2012

Linking the historic 2011 Mississippi River flood to coastal wetland sedimentation

Wetlands in the Mississippi River deltaic plain are deteriorating in part because levees and control structures starve them of sediment. In Spring of 2011 a record-breaking flood brought discharge on the lower Mississippi River to dangerous levels, forcing managers to divert up to 3500 m 3 /s -1 of water to the Atchafalaya River Basin. Here we quantify differences between the Mississippi and Atchafalaya River inundation and sediment-plume patterns using field-calibrated satellite data, and assess the impact these outflows had on wetland sedimentation. We characterize hydrodynamics and suspended sediment patterns of the Mississippi River plume using in-situ data collected during the historic flood. We show that the focused, high-momentum jet from the leveed Mississippi delivered sediment far offshore. In contrast, the plume from the Atchafalaya was more diffuse; diverted water inundated a large area; and sediment was trapped within the coastal current. Maximum sedimentation (up to several centimetres) occurred in the Atchafalaya Basin despite the larger sediment load carried by the Mississippi. Minimum accumulation occurred along the shoreline between these river sources. Our findings provide a mechanistic link between river-mouth dynamics and wetland sedimentation patterns that is relevant for plans to restore deltaic wetlands using artificial diversions.

Atchafalaya River↗
USGS1989

Stetson Pit, Dare County, North Carolina: An integrated chronologic, faunal, and floral record of subsurface coastal quaternary sediments

Continuous split spoon samples from a drill hole penetrating 34 m of coastal plain sediments at Stetson Pit in Dare County, North Carolina were taken for lithologic, aminostratigraphic, faunal (ostracodes) and floral (pollen) analyses. Three distinct aminozones are recognized in the subsurface section based upon D-alloisoleucine/L-isoleucine (A/I) values in each of the molluscan species Mulinia lateralis and Mercenaria sp. Ostracode zonations in the subsurface section are based on percentages of 80 thermophilic and cryophilic species (those living today south and north of Cape Hatteras) and the percentages of brackish water species. Five assemblage zones are delineated. Six pollen assemblage zones are also delineated within the subsurface section based upon study of 48 sediment samples. The subsurface record at Stetson Pit is interpreted to represent portions of four interglacials based upon the combined faunal, floral and aminostratigraphic data. The two younger aminozones, with amino acid age estimates of 100,000±20,000 yr (−7.2 to −11.2 m MSL) and 300,000–500,000 yr (−13 to −14.2 m MSL), represent portions of middle/late Pleistocene interglacials. The lower aminozone (−17.4 to −33 m MSL) spans an interval that probably includes at least two interglacials (based upon faunal and floral records) and has an age estimated to be between 800,000 and 1,300,000 yr. Boundaries delineated by faunal, floral, and amino acid methods do not always coincide, due to sampling constraints and phase lags between the different records. One major unconformity (at −17.4 m MSL) in the Stetson Pit section is easily recognized from lithologic characteristics and may represent a hiatus of as much as 800,000 yr. Lithologic changes associated with all other zone boundaries are subtle and would probably not be considered significant in the absence of faunal, floral, or amino acid data.

North Carolina↗
USGS2020

Louisiana Coastal Zone sediment characterization; comparison of sediment grain sizes for samples collected in 2008 and 2015–2016 from the western Chenier plain to the Chandeleur Islands, Louisiana—Louisiana Barrier Island Comprehensive Monitoring (BICM) Program

Repeated sampling and grain-size analysis of surficial sediments along the sandy shorelines of Louisiana is necessary to characterize coastal-zone sediment properties and evaluate sediment transport patterns within the nearshore environments. In 2008, and again in 2015 and 2016, sediment grab samples were collected along the shorelines of the western Chenier plain, the Isles Dernieres (Raccoon, Whiskey, Trinity and East Islands), the Lafourche delta (Timbalier Islands, Caminada Headland, and Grand Isle), the modern delta (Grand Terre Islands from Chaland Headland to Sandy Point), and the Chandeleur Islands (from Curlew Island to Hewes Point). The samples were collected as part of the Louisiana Coastal Protection and Restoration Authority (CPRA) Barrier Island Comprehensive Monitoring (BICM) Program in collaboration with the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS–SPCMSC) and the University of New Orleans Pontchartrain Institute for Environmental Studies (UNO–PIES). Physical properties of the samples (sediment grain size and sorting) were measured and provided in data reports to CPRA. Additional samples collected by the USGS from around Breton Island in 2014 and 2015 supplemented the 2015–2016 BICM data to complete the coastwide dataset. This report compares the results of the 2008 and 2015–2016 sedimentologic analyses and documents changes in composition (percent sand) and mean sediment grain size between the two time periods. At most sample sites, differences in mean grain size varied by less than ±0.25 Φ. The largest changes occurred at sites located near tidal inlets or along rapidly eroding shorelines.

Louisiana↗
USGS2015

First steps of integrated spatial modeling of titanium, zirconium, and rare earth element resources within the Coastal Plain sediments of the southeastern United States

The Coastal Plain of the southeastern United States has extensive, unconsolidated sedimentary deposits that are enriched in heavy minerals containing titanium, zirconium, and rare earth element resources. Areas favorable for exploration and development of these resources are being identified by geochemical data, which are supplemented with geological, geophysical, hydrological, and geographical data. The first steps of this analysis have been completed. The concentrations of lanthanum, yttrium, and titanium tend to decrease as distance from the Piedmont (which is the likely source of these resources) increases and are moderately correlated with airborne measurements of equivalent thorium concentration. The concentrations of lanthanum, yttrium, and titanium are relatively high in those watersheds that adjoin the Piedmont, south of the Cape Fear Arch. Although this relation suggests that the concentrations are related to the watersheds, it may be simply an independent regional trend. The concentration of zirconium is unrelated to the distance from the Piedmont, the equivalent thorium concentration, and the watershed. These findings establish a foundation for more sophisticated analyses using integrated spatial modeling.

Open-File Report↗
USGS2022

Late Holocene human-environment interactions on the central California coast, USA, inferred from Morro Bay salt marsh sediments

Coastal salt marshes and estuaries provide valuable ecosystem services, yet are susceptible to alteration from human activities. Records of past environmental change in these ecosystems can elucidate relationships between human activities, such as land-use practices, and physical and ecological processes, such as sediment accretion and vegetation changes. To reconstruct the environmental history of one such site, we present inferences based on analysis of sediment cores (including magnetic susceptibility, loss-on-ignition, and pollen) from the Morro Bay salt marsh, located in California’s central coast in the USA. Chronologic control for the sediments was established using radiocarbon dates, a spike in lead (Pb) sourced from gasoline combustion exhaust, and the first identified occurrences of the non-native taxa Erodium cf. cicutarium (filaree) and Eucalyptus . We demonstrate that the Morro Bay watershed was significantly altered following Spanish settlement in the region. Environmental changes associated with livestock grazing and agriculture become evident in the data starting after 1772 CE, when the Mission San Luis Obispo de Tolosa was established nearby. The most prominent changes observed are an increase in the accumulation rate of terrigenous sediment, organic matter, and carbonates, as well as a reduction in arboreal taxa concomitant with increased abundances of shrubs, herbs, and grasses. The expansion of Salicornia (pickleweed) in the 19th century suggests the salt marsh expanded at this time due to increased sediment accumulation and a resulting increase in local elevation. The timing and character of changes recorded in the Morro Bay salt marsh sediments are similar to those documented across California in estuaries, marshes, lakes, and meadows, demonstrating the magnitude of the impacts of European settlement and associated land-use practices in this region.

Anthropocene↗
USGS2006

Simulation of ground-water flow in southeastern Oahu, Hawaii

On the leeward side of southeastern Oahu, Hawaii, near-vertical dikes have intruded the gently dipping and highly permeable lava flows of the Koolau mountain. These dikes bound the study area on the north and west and internally divide it into the Waialae and Wailupe-Hawaii Kai aquifers. Recharge to these aquifers, 6 and 9 million gallons per day respectively, has created Ghyben-Herzberg lenses that freely float on sea water and discharge to the sea through coastal sediments. In the Waialae area, where rainfall is high and where thick (poorly permeable) coastal sediments inhibit the discharge of fresh water, heads are 8 to 15 feet above sea level. Lower rainfall and thin coastal sediments that allow easy discharge cause heads to be only 1 to 5 feet in the Wailupe-Hawaii Kai area. The flow of ground water and the effects of future water development were simulated using AQUIFEM, a two-dimensional finite-element flow model, modified for aquifers containing a sea-water interface. The model provides accurate simulation of observed heads averaged over several years and predicts an additional area-wide head decline of about 1 foot when three recently drilled wells are put into production.

Groundwater↗
USGS2010

Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions

Whether coastal areas are experiencing, and responding to, an accelerated rate of global sea-level rise (GSLR) is critically important for the ∼2 billion people living near Earth's oceans. Accretion rates from a suite of physiographically diverse coastal wetlands surrounding Long Island, NY accelerated during the 20th century at 2.3 ± 0.2 × 10 −2 mm yr −2 , which is comparable to reported rates of GSLR acceleration and global temperature changes. Wetlands varied in tidal range, salinity and geomorphic setting, and were located in embayments with limited human impacts in a region with limited and constant rates of subsidence. From geochronologies with temporal resolutions of 2–5 yr, we constructed new composite histories of sediment accretion and mineral deposition. Wetland dynamics are consistent with predictions from sedimentology and a numerical model of ecogeomorphic response, suggesting that these systems, and likely others worldwide, are responding to accelerated GSLR and related climatic changes.

New York↗
USGS2013

Dispersal of fine sediment in nearshore coastal waters

Fine sediment (silt and clay) plays an important role in the physical, ecological, and environmental conditions of coastal systems, yet little is known about the dispersal and fate of fine sediment across coastal margin settings outside of river mouths. Here I provide simple physical scaling and detailed monitoring of a beach nourishment project near Imperial Beach, California, with a high portion of fines (40% silt and clay by weight). These results provide insights into the pathways and residence times of fine sediment transport across a wave-dominated coastal margin. Monitoring of the project used physical, optical, acoustic, and remote sensing techniques to track the fine portion of the nourishment sediment. The initial transport of fine sediment from the beach was influenced strongly by longshore currents of the surf zone that were established in response to the approach angles of the waves. The mean residence time of fine sediment in the surf zone—once it was suspended—was approximately 1 hour, and rapid decreases in surf zone fine sediment concentrations along the beach resulted from mixing and offshore transport in turbid rip heads. For example, during a day with oblique wave directions and surf zone longshore currents of approximately 25 cm/s, the offshore losses of fine sediment in rips resulted in a 95% reduction in alongshore surf zone fine sediment flux within 1 km of the nourishment site. However, because of the direct placement of nourishment sediment on the beach, fine suspended-sediment concentrations in the swash zone remained elevated for several days after nourishment, while fine sediment was winnowed from the beach. Once offshore of the surf zone, fine sediment settled downward in the water column and was observed to transport along and across the inner shelf. Vertically sheared currents influenced the directions and rates of fine sediment transport on the shelf. Sedimentation of fine sediment was greatest on the seafloor directly offshore of the nourishment site. However, a mass balance of sediment suggests that the majority of the fine sediment moved far away (over 2 km) from the nourishment site or to water depths greater than 10 m, where fine sediment represents a substantial portion of the bed material. Thus, the fate of fine sediment in nearshore waters was influenced strongly by wave conditions, surf zone and rip current transport, and the vertical density and flow conditions of coastal waters.

Journal of Coastal Research↗
USGS2018

Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area, Bohai Sea, China

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg (Pb), 50 mg/kg (Zn), 48.8 mg/kg (Cr), 0.1 mg/kg (Cd), 8.4 mg/kg (As), and 20.3 μg/kg (Hg). These concentrations generally met the China Marine Sediment Quality criteria. However, both pollution assessments indicated moderate to strong Cd and Hg contamination in the study area. The potential ecological risk index suggested that the combined ecological risk of the seven studied metals may be low, but that 24.5% of the sites, where sediments were more finer and higher in Corg concentration, had high ecological risk in Hg and Cd pollution.

Bohai Sea, Hebei Province↗
USGS1993

Holocene sedimentation and coastal wetlands response to rising sea level at the Aucilla river mouth, a low energy coast in the Big Bend area of Florida

The shallow dip of the Florida carbonate platform results in low wave energy on Florida ???Big Bend??? coasts. Therefore sedimentation is dominated by river-and tidal-hydrodynamics near the Aucilla River mouth. Where present, Holocene sediments are thin and unconformably overlie Oligocene-aged Suwannee Limestone. The oldest unlithified sediments include reworked carbonate rubble with clay and wood fragments (seven thousand years old or less, based on wood radio-carbon dating). Although this basal sequence is observed in most areas, the sediments that overlie it vary. Sediment sequences from the outer littoral to submarine environments include organic-rich sands, oyster biotherm remains, and cleaner sands with organic-filled burrows. Inner littoral (salt-marsh) sequences generally consist of sandy, fining-upwards sequences in which dry weights of fine-grained clastics and organic components increase up-sequence at similar rates. Offshore sediments preserve greatly attenuated fluvial and salt-marsh facies, if these facies are preserved at all. With sea-level rise, erosion can result from insufficient sediment supply and down-cutting by tidal currents (Dolotov, 1992; and Dalrymple et al., 1992). Dolotov (1992) attributes displacement of original coastal stratigraphy to insufficient sediments for beach profile maintenance, while Dalrymple et al. (1992) attribute erosional truncation (ravinement) or complete removal of portions of typical estuarine sequences to headward migration of tidal channels.

Conference Paper↗
USGS2025

Geologic framework and Holocene sand thickness offshore of Seven Mile Island, New Jersey

The U.S. Geological Survey assessed the Quaternary evolution of Seven Mile Island, New Jersey, to quantify coastal sediment availability, which is crucial for establishing sediment budgets, understanding sediment dispersal, and managing coastlines. This report presents preliminary interpretations of seismic profiles, maps of Holocene sand thickness from the shoreline to 2 kilometers offshore, and tables quantifying the volume of available sediment along the coastal margin based on data collected during 2021 and 2022. The results reveal spatial variability in the thickness and cross-shore extent of Holocene sand. The study area was separated into northern, central, and southern zones by using underlying stratigraphy and geomorphic features. The characteristics and spatial extent of the Holocene sand deposit indicate that hydrodynamic processes contribute to its spatial variability. Northern Seven Mile Island contains the thickest deposits of Holocene sand that were formed by sediment bypass around the Townsends Inlet ebb-tidal delta. Specifically, swash bars have welded to the updrift end of Seven Mile Island and have formed thick deposits of Holocene sand that thicken landward and taper seaward. Despite their thickness, these deposits have the smallest cross-shore extent; therefore, northern Seven Mile Island has the smallest volume of Holocene sand of the three geomorphic zones. Central Seven Mile Island has the thinnest Holocene sand deposits because this section of the barrier island is outside the influence of ebb-tidal deltas. Southern Seven Mile Island has the greatest volumes of Holocene sand because of increased accommodation and deposition adjacent to the Hereford Inlet ebb-tidal delta. Even though tidal inlets exert variable influence on the three geomorphic zones, sediment is distributed fairly uniformly within each geomorphic zone; each of the three zones contains 31.05–36.48 percent of the volume of available Holocene sand.

New Jersey↗
USGS2009

Delta lobe degradation and hurricane impacts governing large-scale coastal behavior, South-central Louisiana, USA

A large deficit in the coastal sediment budget, high rates of relative sea-level rise (???0.9 cm/year), and storm-induced current and wave erosion are forcing barrier shoreface retreat along the periphery of the Mississippi River delta plain. Additionally, conversion of interior wetlands to open water has increased the bay tidal prism, resulting in degradation of barrier islands due to inlet widening, formation of new inlets, and sediment sequestration at ebb-tidal deltas. Single-beam bathymetric surveys along a 165-km stretch of south-central Louisiana barrier coast, from Raccoon Point in Terrebonne Parish to Sandy Point in Plaquemines Parish, were conducted in 2006. These data, combined with historical bathymetry from three time periods (dating to the 1880s), provide a series of digital elevation models that were used to calculate sediment volumetric changes and determine long-term erosional-depositional trends. Dominant patterns during the 125-year period include (1) erosion of ???1.6????????10 9 m 3 from the shoreface, forcing up to 3 km of shoreface retreat, (2) sediment deposition in coastal bights and at ebb-tidal deltas, and (3) a combined increase in tidal inlet cross-sectional area from ???41,400 m 2 to ???139,500 m 2 . Bathymetric and shoreline change datasets separated by shorter time periods (sub-annual) demonstrate that these long-term trends are driven by processes associated with major hurricane impacts, and that rates of shoreface erosion are an order of magnitude greater during active hurricane seasons compared to long-term trends. ?? 2009 Springer-Verlag.

Geo-Marine Letters↗
USGS1992

A mid-Permian chert event: Widespread deposition of biogenic siliceous sediments in coastal, island arc and oceanic basins

Radiolarian and conodont of Permian siliceous rocks from twenty-three areas in teh the circum-Pacific and Mediterranean regions reveal a widespread Permian Chert Event during the middle Leonardian to Wordian. Radiolarian- and (or) sponge spicule-rich siliceous sediments accumulated beneath high productivity zones in coastal, island arc and oceanic basins. Most of these deposits now crop out in fault-bounded accreted terranes. Biogenic siliceous sediments did not accumulate in terranes lying beneath infertile waters including the marine sequences in terranes of northern and central Alaska. The Permian Chert Event is coeval with major phosphorite deposition along the western margin of Pangea (Phosphoria Formation and related deposits). A well-known analogue for this event is middle Miocene deposition of biogenic siliceous sediments beneath high productivity zones in many parts of the Pacific and concurrent deposition of phosphatic as well as siliceous sediments in basins along the coast of California. Interrelated factors associated with both the Miocene and Permian depositional events include plate reorientations, small sea-level rises and cool polar waters.

western North America↗