Data Management Plan

FEMA Contract No. EME-2003-CO-0340

FEMA Task Order T018

Sanborn Map Company furnished the collection and processing, and development of Lidar and contours using photogrammetry to support the FEMA mapping

requirements for a total of 142 square miles in coastal areas in Plymouth and Bristol Counties in Massachusetts. The 142 square miles includes the

communities of Westport, Dartmouth, New Bedford, Fairhaven, Mattapoisett, Marion, and Wareham. The project area was defined using a buffered shapefile

with limits along the coastline. The project area included a portion of both counties. All lidar data was acquired during November 2006 by Sanborn.

Orthophotography used to create 2D breaklines was produced in 2005 by MassGIS as part of its statewide orthophoto program. All lidar data that

was acquired was produced in accordance with FEMA specifications (Source: FEMA Guidelines and Specifications, Appendix N, Section N.1.2).

Lidar Acquisition Parametes:

Average Altitude: 1,200 Meters AGL

Airspeed: ~120 Knots

Scan Frequency: 36 Hertz

Scan Width Half Angle: 16 Degrees

Pulse Rate: 50000 Hertz

The data being distributed through the NOAA Digital Coast are Gridded Bare-Earth LAS files.

Process Steps:

• 2006-12-31 00:00:00 - Using an Optech Light Detection and Ranging (LiDAR) system, flight lines were planned for standard density 1.4 meter GSD. The Flight plan for the project includes the following specifications to fully meet the project requirements - single pass density of approximately 2.0 square meters per sample * Swath width 728 meters * Flight altitude 1000 meters * flight line spacing -589 meters with 125 meters overlap *Scan Frequency- 35 Hz *Scan Angle- 20 degrees * Aircraft ground speed -- 140 knots * System Calibration pre and post mission * Two GPS base stations within 30 KM. Multiple returns were recorded for each laser pulse along with an intensity value for each return. The data are calibrated for geographic referencing. Points are further processed, using TerraSolid software, to classify return values. The first and last return data is filtered to remove the vegetation and above ground manmade features to yield a ground surface. The bare earth elevation data was draped over the existing orthophotos. Breaklines for hydrographic features, bridges, culverts and major roadways were captured in 2D. Elevations were associated to the breaklines by draping onto the Lidar data. The DTM was then used to produce a TIN. The TIN was used to generate 2-ft contours.
• 2013-11-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received topographic files in ASCII format. The files contained lidar elevation measurements. The data were received in Massachusetts State Plane Mainland (Zone 2001), NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid03 model. The vertical units of the data were feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The ASCII files were converted to LAS V1.2 using LASTools' txt2las. 2. The topographic las file '8002645' was found to be corrupt and removed from the data set. 3. All points in the topographic las files were converted to Class 2 (Ground) using LASTools' las2las. 4. The topographic las files were found to contain noise, those points were manually reclassified to Class 7 (Noise) using Merrick MARS7. 5. All additional VLRs in the topographic las files' header used by MARS7 were removed using LASTools' las2las. 6. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03. 7. The topographic las files were converted from a Projected Coordinate System (MA SP 2001) to a Geographic Coordinate System (NAD83). 8. The topographic las files' horizontal units were converted from feet to decimal degrees. 9. The topographic las files' vertical units were converted from feet to meters.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2602

;