the texas shoreline change project: the texas shoreline change project: combining lidar, historical...
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The Texas Shoreline Change Project:The Texas Shoreline Change Project:
Combining Lidar, Historical Photography, and Ground Surveys to Measure Shoreline Change Rates along Bay and Gulf of Mexico Shorelines
James C. Gibeaut, William A. White, Roberto Gutierrez, Rachel Waldinger, John R. Andrews, Tiffany L. Hepner,
Rebecca C. Smyth, and Thomas A. Tremblay
Bureau of Economic Geology
John A. and Katherine G. Jackson School of Geosciences
The University of Texas at Austin
Shoreline Shoreline LengthLength
Gulf = 600 kmGulf = 600 km
Bays = 9,400 kmBays = 9,400 km
• Mapping past and current shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
Project ComponentsProject Components
Data SourcesData Sources
Before 1930:Maps from the mid to late 1800’s produced by the U.S. Coast Survey – “high-water line mapped.”
Generally not used:Engineering structures altered sediment budget since 1900.
Sand Trapped by Jetty, Southwest end of Bolivar Peninsula (08/07/98)
Data SourcesData Sources
1930’s to 1990’s - Vertical Aerial Photographs
Digital Photo RectificationDigital Photo Rectification
1995 Digital 1995 Digital Orthophoto Orthophoto Quarter Quads Quarter Quads Serve as Base Serve as Base MapsMaps
•USGS/Tx Orthophoto Program
•Scanned color IR film, 1-m resolution
•Meet 1:12,000 map accuracy standards (90% of test points within10 m)
•Our tests show typically within 5 m
Shoreline InterpretationShoreline InterpretationWet/Dry LineWet/Dry Line
Gulf of Mexico
Matagorda Bay
Shoreline InterpretationShoreline InterpretationShoreline and Vegetation LineShoreline and Vegetation Line
Shore andvegetation line
Project ComponentsProject Components
• Mapping shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
1990’s – Kinematic GPS Surveys
Data SourcesData Sources
Project ComponentsProject Components
• Mapping shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
• Mirror sweeps laser beam across the ground.
• Range to target is determined by measuring time interval between outgoing and return of reflected laser pulse.
• Aircraft position is determined using GPS phase differencing techniques.
• Pointing direction of laser determined with Inertial Measuring Unit (IMU) and recording of mirror position.
• Data streams recorded and synchronized for post processing.
GPS ground reference station
Aircraft GPS
GPS satellites
Flight direction
ALTM laser and IMU
Airborne Topographic LidarAirborne Topographic Lidar
GPS Coastal NetworkGPS Coastal Network
GPS base station locationswith 50-km radius circles
Texas Study area
SABP
PTBO
USCG
MATAPTOC
PTAR
QAIL
PTMN
SPAD
Mouth ofRio Grande
Laguna Madre
Matagorda Bay
Corpus Christi Bay
GalvestonBay
SABP U.S. Coast Guard Station, Sabine Pass
PTBO Port Bolivar Tide Gauge
USCG U.S. Coast Guard Station, Freeport
MATA Matagorda Jetty Park, USACE mark
PTOC Port O'Connor Tide Gauge
PTAR Port Aransas
QAIL Padre Island National Seashore
PTMN Port Mansfield Tide Gauge
SPAD U.S. Coast Guard Station, South Padre Island
100 km0
0 50 100 mi
Beach profiles
Lidar Instrument in Cessna 206Lidar Instrument in Cessna 206Optech ALTM 1225Optech ALTM 1225
MHHW +0.6 m msl Geotube
Landward boundaryBEG-02
Beach profile
QAd496Gibeaut_CCC_Jan31_2002
Lidar Digital Elevation ModelLidar Digital Elevation Model1 - m grid1 - m grid
• Ellipsoidal heights converted to orthometric heights (NAVD 88) using GEOID99 gravity model.
• Local mean sea level (MSL) correction applied.
Calibration TargetCalibration Target
Calibration Flight LinesCalibration Flight Lines
0 2 mi
2 km0
Gulf of Mexico
Kinematic surveydata points
Calibration aircrafttrajectory
Shoreline aircrafttrajectory
Galvestoncounty roads
Environmentalsensitivity index
Lidar Survey VideoLidar Survey Video
Galveston BeachGalveston Beach
Wet/Dry Line
Galveston Island ProfileGalveston Island Profile
Lidar last return
Total station ground survey
Lidar last return intensity
Vertical exaggeration 50
Geotube
Vegetation
Monument
Wet/dry line
Water surface
+0.6 m above MSL
0
50
100
150
200
250
300
350
400
–200 –150 –100 –50 0 50 100 150 200 250Distance from monument (m)
–30
–29
–28
–27
–26
–25
–24
Representative Wet/Dry ElevationRepresentative Wet/Dry Elevation0.6 m along Upper Tx Gulf Coast0.6 m along Upper Tx Gulf Coast
0
1
2
3
-1
-2
0.6MHHW
0 100
Hei
ght r
e la t
ive
to M
SL
(m)
Distance (m)
50
upper berm crest
vegetation line
Why Use a Wet/Dry Why Use a Wet/Dry Elevation?Elevation?
• Consistent with historical photography.
• Consistent with 2d ground GPS surveys.
• Lidar can measure reliably even during elevated water levels.
• Geomorphologically significant elevation not as susceptible to short-term erosion/depositional cycles compared to lower elevations.
Hand-Smoothed ShorelineHand-Smoothed Shoreline
Project ComponentsProject Components
• Mapping shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
Shoreline Shape and Shoreline Shape and Projection ProgramProjection Program
ArcView InterfaceArcView Interface
-250
-200
-150
-100
-50
0
50
100
150
200
1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060
Shoreline
Long-term end point rate
Mid-term/linear regression rate
Year QAb5370c
BureauofEconomic
Geology
Shoreline Change RateShoreline Change Rate
Projected ShorelineProjected ShorelineGalveston IslandGalveston Island
Project ComponentsProject Components
• Mapping shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
Ground SurveyGround Survey
Beach ProfileBeach ProfileAnnotatedAnnotated
Project ComponentsProject Components
• Mapping shorelines
– Aerial photography
– Ground kinematic GPS
– Airborne lidar – shoreline plus beach and dune topographic mapping
• Calculating “average annual rate of change” and projecting future shoreline position
– GIS-based Shoreline Shape and Projection Program (SSAPP)
• Beach profile ground surveys
• Data availability and public awareness
– Online reports
– Web-based GIS using ArcIMS software
www.beg.utexas.edu/coastalwww.beg.utexas.edu/coastalwww.beg.utexas.edu/coastalwww.beg.utexas.edu/coastal