scholarly journals A survey of storm-induced seaward-transport features observed during the 2019 and 2020 hurricane seasons

Shore & Beach ◽  
2021 ◽  
pp. 31-40
Author(s):  
Jin-Si Over ◽  
Jenna Brown ◽  
Christopher Sherwood ◽  
Christie Hegermiller ◽  
Phillipe Wernette ◽  
...  
Keyword(s):  
North Carolina ◽  
Emergency Response ◽  
Critical Role ◽  
Geodetic Survey ◽  
Return Flow ◽  
National Geodetic Survey ◽  
Coastal Change ◽  
Coastal Evolution ◽  
The North ◽  
Flow Features

Hurricanes are known to play a critical role in reshaping coastlines, but often only impacts on the open ocean coast are considered, ignoring seaward-directed forces and responses. The identification of subaerial evidence for storm-induced seaward transport is a critical step towards understanding its impact on coastal resiliency. The visual features, found in the National Oceanic and Atmospheric Administration, National Geodetic Survey Emergency Response Imagery (ERI) collected after recent hurricanes on the U.S. East Atlantic and Gulf of Mexico coasts, include scours and channelized erosion, but also deposition on the shoreface or in the nearshore as deltas and fans of various sizes. We catalog all available ERI and describe recently formed features found on the North Core Banks, North Carolina, after Hurricane Dorian (2019); the Carolina coasts after Hurricane Isaias (2020); the Isles Dernieres, Louisiana, after Hurricane Zeta (2020); and the southwest coast of Louisiana, after Hurricanes Laura and Delta (2020). Hundreds of features were identified over nearly 200 km of coastline with the density of features exceeding 20 per km in some areas. Individual features range in size from 5 m to 500 m in the alongshore, with similar dimensions in the cross-shore direction, including the formation or reactivation of outlets. The extensive occurrence of these storm-induced return-flow and seawardflow morphologic features demonstrates that their role in coastal evolution and resilience may be more prominent than previously thought. Based on these observations we propose clarifying terms for return- and seaward-flow features to distinguish them from more frequently documented landward-flow features and advocate for their inclusion in coastal change hazards classification schemes and coastal evolution morphodynamic models.

scholarly journals A survey of storm-induced seaward-transport features observed during the 2019 and 2020 hurricane seasons

2021 ◽  
Author(s):  
Jin-Si Over ◽  
Jenna Brown ◽  
Chris Sherwood ◽  
Christie Hegermiller ◽  
Phillipe Wernette ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Critical Role ◽  
Geodetic Survey ◽  
Return Flow ◽  
National Geodetic Survey ◽  
Coastal Evolution ◽  
The North ◽  
Island Evolution ◽  
Flow Features ◽  
The Impact

Hurricanes are known to play a critical role in reshaping coastlines, particularly on the open ocean coast in cases of overwash, but storm induced seaward-directed flow and responses are often ignored or un-documented. Subaerial evidence for seaward sediment transport (outwash, return-flow) increases our understanding of the impact hurricanes have on coastal and barrier island evolution. Towards this goal we catalog all available National Geodetic Survey Emergency Response Imagery (ERI), the National Oceanic and Atmospheric Administration’s (NOAA) collection of post-hurricane aerial imagery on the U.S East Atlantic and Gulf of Mexico coasts, for visible washout and return flow features. The most recent examples are from the North Core Banks, North Carolina, after Hurricane Dorian (2019), the Carolina coasts after Hurricane Isaias (2020), the Isles Dernieres, Louisiana, after Hurricane Zeta (2020), and the southwest coast of Louisiana, after Hurricanes Laura and Delta (2020); these include erosive scours and channels but also depositional deltas and fans on the shoreface and nearshore. Over the nearly 200 km of coastline analyzed, hundreds of seaward-flow features were identified; the density exceeds 20 per km in some areas. Individual features measure between 5 m and 500 m in both the along- and cross-shore dimensions. The extensive occurrence of these storm-induced return-flow and outwash morphologic features demonstrates that their sediment transport role may be more influential than previously thought. Based on these observations, we advocate for their inclusion in coastal change hazards classification schemes and coastal evolution morphodynamic models and propose an adoption of direction-explicit terms to use when describing return- and seaward-flow features to reduce redundant jargon and distinguish them from more frequently documented landward-flow features.

The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 

2021 ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric ◽  
Ryan Hardy ◽  
...  
Keyword(s):  
North American ◽  
Gravity Data ◽  
The United States ◽  
Geodetic Survey ◽  
Airborne Gravity ◽  
Data Sets ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
Satellite Gravity ◽  
The North

<p>For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1’x1’ grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east. xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3” grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the relative geoid accuracy could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.</p>

scholarly journals Tidal Datums with Spatially Varying Uncertainty in North-East Gulf of Mexico for VDatum Application

2018 ◽  
Vol 6 (4) ◽  
pp. 114 ◽  
Author(s):  
Liujuan Tang ◽  
Edward Myers ◽  
Lei Shi ◽  
Kurt Hess ◽  
Alison Carisio ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Measurement Errors ◽  
Deep Ocean ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Model Errors ◽  
Large Uncertainty ◽  
North East ◽  
The North ◽  
Spatially Varying

We conducted a VDatum-spatially varying uncertainty study for the North-East Gulf of Mexico. The newly developed tide model incorporated the latest available National Ocean Service (NOS) bathymetry survey data and National Geodetic Survey (NGS) shoreline data, and the datum products reflected the updated tidal datum data from the Center for Operational Oceanographic Products and Services (CO-OPS). A gridding technique based on the wavelength of long waves in the deep ocean was applied to improve model efficiency. In this study, we highlight the creation of the tidal datum products and associated spatially varying uncertainty, which was developed by blending the model results, observations, and measurement errors together using a spatially varying uncertainty method based on a variational approach. The study found that model errors, measurement errors, and lack of observations can contribute to large uncertainty in the tidal datum products. The need for high quality bathymetry data in coastal areas is essential for reducing model error. As for the large uncertainty due to lack of observations or large measurement error, this can be improved by placement of new observations with high precision. Compared to a single uncertainty value, the spatially varying uncertainty provides more accurate representation of the uncertainty for the tidal datum products in VDatum. The uncertainty results will be used to help with decision-making on placement of new tide gauges to further reduce the uncertainty in the VDatum products.

scholarly journals Subsidence determination in the Central Valley, California

2018 ◽  
Vol 106 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Marcelo Romero ◽  
Mike Mustafa Berber
Keyword(s):  
Central Valley ◽  
Satellite System ◽  
Geodetic Survey ◽  
Reference Station ◽  
National Geodetic Survey ◽  
The North ◽  
Elevation Changes ◽  
System Data ◽  
Global Navigation Satellite ◽  
Gnss Data

Abstract Twenty four hour GNSS (Global Navigation Satellite System) data acquired monthly for 5 years from 8 CORS (Continuously Operating Reference Station) stations in Central Valley, California are processed and vertical velocities of the points are determined. To process GNSS data, online GNSS data processing service APPS (Automatic Precise Positioning Service) is used. GNSS data downloaded from NGS (National Geodetic Survey) CORS are analyzed and subsidence at these points is portrayed with graphics. It is revealed that elevation changes range from 5 mm uplift in the north to 163 mm subsidence in the southern part of the valley.

The north american vertical datum of 1988 (navd ‘88) internal status report prepared for cism ‘88 winnipeg, manitoba may 24-27, 1988

CISM journal ◽  
1989 ◽  
Vol 43 (4) ◽  
pp. 387-393
Author(s):  
Fred W. Young ◽  
John Murakami
Keyword(s):  
North American ◽  
The United States ◽  
Geodetic Survey ◽  
Background Information ◽  
Status Report ◽  
National Geodetic Survey ◽  
The North ◽  
Vertical Datum ◽  
History Of ◽  
Expected Benefits

Canada and the United States through their respective national geodetic survey organizations have been cooperating in a project to redefine the heights for bench marks in North America. This report will deal with a history of the levelling network in Canada, provide background information about the North American Vertical Datum of 1988 (NAVD ‘88) Project itself, give an update concerning key Canadian activities and tasks related to the project, and finally state the expected benefits of such an undertaking.

scholarly journals REPLACING NAVD88: THE EFFECTS OF VERTICAL DATUM MODERNIZATION ON COASTAL ENGINEERING

2018 ◽  
pp. 58
Author(s):  
Nicole Kinsman ◽  
Monica Youngman
Keyword(s):  
Mississippi River ◽  
North American ◽  
Vertical Motion ◽  
The United States ◽  
Satellite System ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
The North ◽  
Vertical Datum

The United States (US) National Geodetic Survey (NGS) will be replacing the North American Vertical Datum of 1988 (NAVD88) with the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). NAVD88 is still the official vertical datum of the NSRS at this time, but it is in need of improvement; it is both biased (by about one-half meter) and tilted (about 1 meter coast to coast) relative to the best global geoid models available today. This issue stems from the fact that NAVD88 was defined primarily using terrestrial surveying techniques at passive geodetic survey marks. For access, users must often collect hours of Global Navigation Satellite System (GNSS) data, or rely on our nation’s network of passive survey marks, which is not fully stable (consider areas of subsidence such as the Mississippi River delta) and is deteriorating over time. Maintenance of these marks requires significant resources and vertical motion of marks is not tracked in a systematic way. A modernized vertical reference frame will primarily rely on GNSS such as the Global Positioning System (GPS) in combination with an updated and time-tracked geoid model. This paradigm shift will result in improvements to the National Spatial Reference System (NSRS) that will provide users with enhanced access, easier maintenance, and more consistent coordinates for precise positioning activities nationwide.

Modernizing the Datums of the National Spatial Reference System

2015 ◽  
Vol 49 (2) ◽  
pp. 151-158
Author(s):  
Dru A. Smith ◽  
Daniel R. Roman ◽  
Vicki A. Childers
Keyword(s):  
North American ◽  
Reference System ◽  
Passive Control ◽  
The United States ◽  
Geodetic Survey ◽  
Federal Agencies ◽  
National Geodetic Survey ◽  
Spatial Reference ◽  
The North ◽  
Vertical Datum

AbstractThe National Spatial Reference System (NSRS) is the official coordinate system for all geospatial activities performed by civilian federal agencies of the United States, including National Oceanic and Atmospheric Administration's navigational charts. Two of the datums that make up the bulk of the NSRS, the North American Datum of 1983 (NAD 83) and the North American Vertical Datum of 1988 (NAVD 88), were created with the most accurate surveying technology available in the 1970s and 1980s. However, analysis over the last decade has proven that both datums contain systematic errors at the few meters level. While there have been improvements to these datums over the years, they have all been restricted to adjusting subsets of coordinates within the datum, rather than replacing the datum itself. However, the rise of near-real-time positioning technologies at the few centimeter level has made it no longer viable to maintain the two datums.The National Geodetic Survey is engaged in a decade-long effort to prepare the NSRS user community and collect the necessary data to define two new datums that will not only replace NAD 83 and NAVD 88 but also reduce the overall reliance of those two datums on passive control. The two new datums are expected to be completed and jointly released in 2022.

Development and evaluation of the xGEOID20 Digital Elevation Model at NGS

2020 ◽  
Author(s):  
Jordan Krcmaric
Keyword(s):  
Digital Elevation Model ◽  
Geoid Undulation ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
The North ◽  
Digital Elevation ◽  
Vertical Datum ◽  
Elevation Model ◽  
Ellipsoid Heights

<p>The U.S. National Geodetic Survey (NGS), an office of the National Oceanic and Atmospheric Administration (NOAA), will release a new vertical datum in 2022, the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This new datum will be based on a high degree spherical harmonic model of the Earth’s gravitational potential, and will yield a geoid undulation model (GEOID2022) to calculate orthometric heights from GNSS-derived ellipsoid heights.</p><p>In preparation for the new vertical datum, NGS has computed annual experimental geoid models (xGEOID) since 2014. This year’s xGEOID model (xGEOID20) will use an updated digital elevation model (DEM) composed of TanDEM-X, 3DEP, MERIT, and other DEMs. The DEMs are merged together to create a seamless elevation model across the extent of the xGEOID20 model. The accuracy of the merged DEM is tested using independent datasets such as GPS on benchmarks and Icesat-2. The effect of the updated DEM on the geoid model is also determined by comparing geoid models computed with previous DEMs to the new xGEOID20 model, and with comparisons to the NGS Geoid Slope Validation Survey lines.</p>

Sign in / Sign up

Export Citation Format

Share Document