2002 NOAA Lidar: Willapa Bay, WA Mudflat (WA)

NOAA contracted with Spencer B. Gross, Inc. (SBG) to obtain airborne Lidar of Willapa Bay, Washington during low tide

conditions. The Lidar data was processed to deliver topographic surface elevation data of the exposed intertidal flats and surrounding

terrestrial areas.

Original contact information:

Contact Org: NOAA Office for Coastal Management

Phone: 843-740-1202

Email: coastal.info@noaa.gov

The elevation data will be used to investigate the impacts of invasive species on the local ecology.

10244

The tide patterns of Willapa Bay required that the project area be divided into three sections, and Lidar

flights had to be flown in an East/West orientation to capture the low, low tide conditions. As the tidal waters moved throughout

the Bay, flights were completed according to tide data provided by the University of California - Davis (Evolution & Ecology Dept.).

Flights were completed during all acceptable periods - day or night.

The Willapa Bay, WA Lidar project boundary may be viewed at: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/12/supplemental/wa2002_noaa_willapa_mudflat_m12.kmz

The Willapa Bay, WA Lidar Data Validation Report may be viewed at: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/12/supplemental/wa2002_noaa_willapa_mudflat_m12_surveyreport.pdf

Any conclusions drawn from analysis of this information are not the responsibility of NOAA, 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=12

The data set is dynamically generated based on user-specified parameters.

;

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of the data

may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness

of its limitations.

Independent ground control points were acquired using static GPS methods in flat open areas throughout the

project area. These points were estimated to have a vertical accuracy of 0.02m. The processed lidar data were compared to ground

control points within the project. Lidar points surrounding the x-y of each ground control point were located. A triangulated irregular

network (TIN) model was created and a z value was interpolated. The interpolated Lidar z value at ground control x-y was compared to

the ground control z. The mean elevation difference for all comparison was used to estimate and remove an elevation bias within the

Lidar data. The elevation bias was determined to be 0.137m. Removal of the bias resulted in a RMSE of 0.128m. Processing steps

(datum conversion, projection, grid interpolation, etc.) introduce additional error factors which have not been tested and factored

into the reported error.

RMSE at 1 sigma = 21 cm

RMSE at 1 sigma = 12.8 cm

None available

Lidar Specifications: 7,000-feet AMT flight height; 24 degree field of view, 2.84-meter average post-spacing,

2978-foot swaths flown with 30% sidelap, 24,000 pulses per second; 1+1 collection (one return and one intensity value per pulse).

Lidar flown with an ADS40, Leica Geosystems Lidar system, February 2002 model. The flight consisted of 71 E/W flight lines with 2 N/S

cross flight lines for data calibration purposes: 800 flight line miles covering 274 square miles. For each lift, 2 flight lines were

flown at the Astoria, OR airport for system calibration purposes.