2010 Federal Emergency Management Agency (FEMA) Topographic Lidar: Coastal Massachusetts and Rhode Island

Terrain data, as defined in FEMA Guidelines and Specifications, Appendix N: Data Capture Standards, describes the digital topographic data that was used to

create the elevation data representing the terrain environment of a watershed and/or floodplain. Terrain data requirements allow for flexibility in the

types of information provided as sources used to produce final terrain deliverables. Once this type of data is provided, FEMA will be able to account for the

origins of the flood study elevation data. (Source: FEMA Guidelines and Specifications, Appendix N, Section N.1.2).

Terrain data is used to represent the topography of a watershed and/or floodplain environment and to extract useful information for hydraulic and hydrologic

models. (Source: FEMA Guidelines and Specs, Appendix N) This digital data is produced for the purposes of updating/creating a DFIRM database.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2555/supplemental/ne2010_fema_coastalmari_footprint.KMZ

A vertical accuracy report from the vendor may be viewed here:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2555/supplemental/ne2010_fema_coastalmari_accuracyreport.pdf

LiDAR points in LAS 1.2 format (ASPRS Classes 1,2,7,9,10,12)

Appendix M of FEMA Guidelines and Specifications for FEMA Flood Hazard Mapping Partners contains a detailed description of the data themes and references

to other relevant information.

Any conclusions drawn from the analysis of this information are not the responsibility

of Aero-Metric, CDM, STARR, FEMA, NOAA, the Office for Coastal Management or its partners.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2555

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Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual

surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. These data depict the heights at

the time of the survey and are only accurate for that time.

Vertical testing methods derived from the NSSDA/FEMA guidelines. 131 checkpoints were collected throughout entire project area (including 7 control points).; Quantitative Value: 0.16 meters, Test that produced the value: NSSDA AccuracyZ (RMSEz x 1.9600 = 95% confidence level). Value in meters.

Data contained in the Terrain package highlights specific issues in the Elevation datasets. Terrain data are derived datasets that aid automated

hydrologic and hydraulic analyses, the flood hazard area boundary delineations, and quality control.

The Terrain data are consistent with the Elevation dataset. A comparison of profile plots with the flow vector data confirms that flow vectors are correctly drawn.

Flood hazard boundaries do not extend beyond the External Boundary, if exists. FIRM panels show the flood hazard area delineations where Island data are present.