After severe Nor'easter storms in January and February, 1998, a constructed berm was installed on the northend of Assateague Island through a partnership including Assateague Island National Seashore, US Army Corps of Engineers, and MD Department of Natural Resources. In 2002, the berm was rebuilt, and in January 2005, notches were created through the berm by a bulldozer in an attempt to re-introduce natural overwash processes. These notches are monitored every month, through collecting elevation surveys, in addition to one survey prior to the notching. These surveys can be used to create an elevation surface.
This survey was collected immediatly after the notches were created in January, 2005. This is the first of monthly monitoring surveys to examine how the notches are evolving. This survey can also be used with the pre-notch dataset to determine how much sediment was moved from the berm.
Elevations will be collected over each notch once a month, except for May - Aug, during which the threatened Piping Plover nests in these locations. These surveys are stored as shapefiles, and titled 'asisberm_notchYYYYMM', where YYYY stands for the year, and MM stands for the month of the survey.
ground condition
none
7206 National Seashore Lane
ASIS GIS Staff
Attributes are accurate as recorded in the field or within the tolerances set in Trimble Geomatics Office. There are no apparent inconsistencies in the attributes. Attributes that were not accurate were corrected in Trimble Geomatics Office.
Horizontal and vertical accuracy checks were conducted over known monuments and error was found to be <0.005m horizontal and <0.010m vertical at all monuments. Data that did not meet RMS, PDOP, SNR and other criteria were discarded.
Each of the six notches were surveyed and data points were collected at an average spacing of 2-4 meters, or when breaks in slope were encountered.
Horizontal accuracy is reported as <0.015m. Positions with accuracy >0.015m are reported, however these positions are of suspect quality.
See accuracy report.
Vertical accuracy is reported as <0.015m. Positions with accuracy >0.015m are reported, however these positions are of suspect quality.
See accuracy report.
The number and location of notches along the constructed berm were determined by Assateague Island NS Resource Management staff and US Army Corps of Engineers. Once a month these notches are surveyed to determine how they are developing and if overwash is occuring. The location of each notch was initially staked out, and can now be found through this and the other previous surveys. A Trimble 5700 total station was used to collect the elevation points. RTK collection was utilized with the base radio broadcasting at 25khz. The base station was set up on known monuments and all data collection was RTK. The base station occupied GPS3 or GPS5. The exact location can be found in the Trimble Geomatics Office original data file. The surveyor used the rover unit, and walked parrell to the shore, perpendicular to the berm notch, back and forth, and collected a point at every 5 seconds or break in slope. This allows for a spacing of 2-4 meters, so there is enough time left to balance the rover pole. The rover and base were set with an elevation mask of 12 degrees, SNR mask of 6.0, and PDOP mask of 6.0. Data was examined in Trimble Geomatics Office and exported as a x,y,z table, which was then converted into a ESRI GIS shapefile.
7026 National Seashore Lane
Internal feature number.
ESRI
Feature geometry.
ESRI
Name of survey point, first character represents notch number (from north to south), 'n' or 'nn' stands for notch and serves as a seperator, second number is a unique sequential whole number for each point in the notch survey.
Trimble Geomatics Office
Point description (if needed).
ASIS
Comments recorded by surveyor, most often signifies the notch number (from north to south).
ASIS
Northing coordinate in UTM, Zone 18, NAD83
UTM Projection
Easting coordinate in UTM, Zone 18, NAD83
UTM Projection
Elevation of each point in NAVD88
NAVD88
Year of data collection.
Calendar
Month of data collection.
Calendar.
Day of data collection.
Calendar.
Time of data collection.
Local time (EST).
Point coordinate latitude in a geographic projection, NAD83.
Trimble Geomatics
Point coordinate longitude in a geographic projection, NAD83.
Trimble Geomatics
Height of the ellipsoid, used to calculate elevation.
Trimble Geomatics
RMS error within each point in meters.
Trimble Geomatics
Number of satellites used in determining point position.
Trimble Geomatics
Precision of horizontal coordinates.
Trimble Geomatics
Precision of elevation measurement.
Trimble Geomatics
The notch number, starting from the northernmost notch (1) to the furthest south (6).
ASIS
7206 National Seashore Lane
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7206 National Seashore Lane