In the summer of 2003, NRM Personnel and cooperators installed and surveyed-in survey markers (steel pipe, survey nails), and water level Staff Gauges at freshwater pond sites in the study area of ASIS Maryland using a total station and traditional surveying methods. These data are the positions of permanent monitoring stations (Staff Gauges), from which pond water level will be tracked, and of permanent survey markers, or 'benchmarks', from which future measurements and calibrations can be staged.
The purpose of this data set is to obtain real-world coordinates and elevations for these installations that they may be referred to Sea Level - an important aspect of the questions surrounding ASIS pond dynamics - and re-calibrated, measured, and recovered using related methodologies.
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7206 National Seashore Lane
All attempts are made to perform mapping at the time when water level conditions are nearest to "normal". Monitoring of weather over the period leading up to collection, monitoring of regional real-time tide levels as observed against predictions (and subsequent extrapolation to OC), and visual observations are all used to predict a best day. On days of data collection, a GPS position is taken of a known point - a permanent monument - and the collected position is compared to the known coordinates to insure accuracy. All collected files are normally differentially corrected using the base station files from NJDEP, Trenton, NJ. NJDEP files were not used in this instance because the known point was collected after 20:00 EDT - the stopping point of NJDEP file collection. Base station correction files were instead obtained from VIMS (per recommendation of the NPS CRGIS base station site, which was unavailable for the time period). The accuracy of the Northing and Easting coordinates was sub-meter for this survey. A note on file editing: in summer 2002, the GIS/Geomorphology section of ASIS-NRM instituted new shoreline processing procedures. This file was processed using these general guidelines to editing: Check for errors by scrolling one frame at a time through the entire map at a 1:2,000 Scale. Gaps of 5 meters or less can be joined as long as you are certain they were unintentional/errors, and not true features (like a temporary stream/inlet). Use great care in joining and if you are adding vertices; try to mimic natural line-flow as best as possible. Obviously unintentional clustering (E.g., explained by points taken while standing still) of non-line points should be cleared up by deleting carefully chosen points. Post-collection editing of note for this shoreline: originally comprised of two features, these were joined together as the seperation was due only to a battery change.
Topology was created for this data set.
This data set contains the locations of permanent survey equipment for monitoring the level of fresh water ponds on Assateague Island National Seashore
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The Nikon Top Gun total station (model DTM-A10LG, ca. 1994) is set up above monuments, and it is then oriented by backsighting to another known point (monument or witness post). Data points (coordinates and elevation) are then collected from a fixed height and orientation above the monument. When line-of-sight to point of interest is not available, a station reset is performed at intervening temporary set-up points (maintaining line-of-sight for backsight and new point collection). Pond Survey Markers (posts and survey nails) were installed according to convenience for calibration and measuring, and then positions of tops of markers were collected. Staff Gauges were installed according to ease of view from shores, and appropriate depth for long-term monitoring; position data are points directly adjacent (~3.5-6.5cm) to the gauges. Ponds were located with GPS, naming convention and metadata were done at a later date.
7206 National Seashore Lane
Dataset copied.
Internal feature number.
ESRI
Feature geometry.
ESRI
ASIS
Coordinates used to determine exact feature location
ASIS
Coordinates used to determine exact feature location
ASIS
7206 National Seashore Lane
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7206 National Seashore Lane