National Park Service

Northeast Coastal and Barrier Network (NCBN)

Coastal Geomorphology Monitoring

Beach at Sagamore Hill NHS
Beach at Sagamore Hill NHS

Resource Brief – Ocean Shoreline Position

Monitoring Reports

Monitoring Data

NCBN Geomorphological Monitoring Protocol:
Part I – Ocean Shoreline Position

For more information contact: Sara Stevens or
Dennis Skidds

Importance / Issues

A major issue in all coastal parks is the magnitude and rate of shoreline change. This condition affects the quality of the natural and cultural resources as well as the general infrastructure present in the coastal parks. It is among the most basic concerns of being at the shore. It is estimated that at least 70% of the world's sandy shorelines are eroding, and the percentage is expected to increase because of sea-level rise and sediment manipulation by human actions.

The problem of land loss/gain and landscape alteration at the marine edge is fundamental to many issues facing coastal park resource stewards. A primary goal of the NCBN coastal geomorphological program is to provide information to park managers and to improve the understanding of the dynamic nature of coastlines, including the temporal and spatial patterns of change in NCBN parks, for use in management decisions and in describing the condition of marine and coastal areas.

Monitoring Objectives

Determine long-term trends in the seasonal and annual variability in shoreline position for the ocean shoreline in Network parks.

Characterize and improve understanding of how long term trends in marine hydrodynamic processes (tide, current and wave), offshore topography (sediment quality, bathymetry and location of migrating shoals and bodies) and the location of man-made structures influence NCBN park beach/dune systems.

Parks Monitored

  • Assateague National Seashore (ASIS)
  • Cape Cod National Seashore (CACO)
  • Fire Island National Seashore (FIIS)
  • Gateway National Recreation Area (GATE)
  • George Washington Birthplace National Monument (GEWA)
  • Sagamore Hill National Historic Site (SAHI)

Approach

GPS surveys are conducted along the entire shoreline of each park twice a year (spring and fall) in order to accurately map the position of the high-tide swash line. Surveys along the ocean shoreline are accomplished by driving a four-wheel all terrain vehicle (ATV) at a relatively constant speed with the GPS receiver configured to record positions at a very short interval (typically one position per second or roughly every 5 meters).

The USGS Digital Shoreline Analysis System (DSAS) tool is then used to transform the surveyed shorelines into a data matrix of distance measurements from which temporal and spatial changes are determined. Creation of the data matrix provides the basis to characterize the dimensional changes of the entire park's shoreline as well as subsets of the park (smaller areas of special concern).

Assateague National Seashore
Assateague National Seashore

NCBN Geomorphological Monitoring Protocol: Part II – Coastal Topography

Monitoring Reports

Monitoring Data - LiDAR

For more information contact: Sara Stevens or
Dennis Skidds

Importance / Issues

Dune, cliff, and bluff erosion and migration often involve direct threats to resources, buildings and infrastructure, and even to human safety, and are a major management issue in many parks.

Over wash fans and flood plains serve as indicators of potential change and can provide early warning to park managers of an impending issue or of a need for additional monitoring and research.

Monitoring Objectives

Determine trends and characterize the variability in beach-dune topography of the ocean coastline in Network parks over seasonal, annual, and long-term scales.

Characterize and improve understanding of how long term trends in marine hydrodynamic processes (tide, current and wave), offshore topography (sediment quality, bathymetry and location of migrating shoals and bodies) and the location of man-made structures influence NCBN park beach/dune systems.

Parks Monitored

  • Assateague National Seashore
  • Cape Cod National Seashore
  • Fire Island National Seashore
  • Gateway National Recreation Area

Approach

Changes in features including dunes, cliffs, shore lines, over wash fans, etc., will be monitored using state-of-the-art, high-accuracy GPS/GNSS survey equipment to acquire topographic data along pre-established beach-dune profiles at regular intervals. A Spatial Monuments Network of high-quality reference points will be established for each of the NCBN parks, providing a robust geodetic control for long-term monitoring. Spring and fall surveys will be conducted in order to examine seasonal, annual, and long-term change. In addition to monitoring long-term topographic changes, data acquired through this protocol will be used to examine the effects of jetties, shoreline armoring, dredge channels, beach nourishment sites, and dune manipulations.

Historical DTM and orthophoto for FIIS (1969)
Historical DTM and orthophoto for FIIS (1969)

Historical Digital Terrain Models

Historical Orthophoto Mosaics

For more information contact: Sara Stevens or
Dennis Skidds

Overview

The NCBN partnered with the USGS Patuxent Wildlife Research Center Coastal Field Station, located at the University of Rhode Island, to develop a baseline of historical topography to be utilized in long-term topographic change analyses in four coastal parks: Fire Island National Seashore (FIIS), Cape Cod National Seashore (CACO), Gateway National Recreation Area (GATE), and Assateague Island National Seashore (ASIS).

The historical topographic models produced for this project will provide the ideal baseline information for incorporation into models that will further the understanding of the potential impacts of sea-level rise to the coastal parks. The most fundamental knowledge required for understanding how coastal systems may behave in the future is how they have behaved in the past. Historical shoreline change data exist for most areas, but analyses of such data are restricted to 2-dimensional assessments of a line near water level on the beach, thus providing little information on the back beach and dune areas. The photogrammetric products generated for this project are the only available source of historical topographic data for these areas, and include not only historical digital terrain models but the generation of historical orthophotographs as well.

Last Updated: December 07, 2017 Contact Webmaster