Derivation of ground surface and vegetation in a coastal Florida wetland with airborne laser technology By Ellen A. Raabe, Melanie S. Harris, Ramesh L. Shrestha, and William E. Carter Open-File Report 2008–1125 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Reston, Virginia 2008 Revised and reprinted: 2008 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Suggested citation: Raabe, E.A., Harris, M.S., Shrestha, R.L., and Carter, W.E., 2008, Derivation of ground surface and vegetation in a coastal Florida wetland with airborne laser technology, U.S. Geological Survey, Open-File Report 2008-1125, Saint Petersburg , FL, 41 p. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. ii Contents Figures................................................................................................................................................................................. iii Photos ..................................................................................................................................................................................iv Tables...................................................................................................................................................................................iv Abstract.................................................................................................................................................................................1 Introduction ......................................................................................................................................................................1 Study Area........................................................................................................................................................................2 Methods................................................................................................................................................................................5 Ground Control ................................................................................................................................................................5 ALSM Data Acquisition and Processing ....................................................................................................................6 Digital-Surface Model ...................................................................................................................................................7 Results...................................................................................................................................................................................8 Bare-Earth DSM ..............................................................................................................................................................8 Vegetation-Canopy DSM.............................................................................................................................................16 Land-Cover Maps..........................................................................................................................................................21 Shoreline ........................................................................................................................................................................26 Geomorphic-Profile Transects ...................................................................................................................................27 Discussion ..........................................................................................................................................................................32 Acknowledgments ............................................................................................................................................................32 References Cited ..............................................................................................................................................................33 Appendix I...........................................................................................................................................................................35 Figures Figure 1. Locations of airborne laser-altimetry flights at Lukens Creek, Bird Creek, and Waccasassa, August, 17, 1999. ..................................................................................................................................................................3 Figure 2. Example data cloud and break points for functional landscape units. ...................................................8 Figure 3a, b. Differences between field-surveyed and surface-model elevations using 2-, 5-, and 10-m filters for a) marsh at Lukens Creek, b) forest and thick marsh. ................................................................................9 Figure 4. (a) Orthophotoquad, and (b) ground-surface DSM at Lukens Creek. .....................................................10 Figure 5. (a) Orthophotoquad, and (b) ground-surface DSM at Bird Creek and Waccasassa. .........................10 Figure 6. Bare-earth digital-surface model at Lukens Creek derived from ALSM. ..............................................12 Figure 7. Bare-earth digital-surface model at Bird Creek derived from ALSM....................................................13 Figure 8. Bare-earth digital-surface model at Waccasassa River derived from ALSM. ....................................14 Figure 9. Canopy-height digital-surface model at Lukens Creek derived from ALSM. .......................................17 Figure 10. Canopy-height digital-surface model at Bird Creek derived from ALSM. ..........................................18 Figure 11. Canopy-height digital-surface model at Waccasassa River derived from ALSM. ...........................19 Figure 12. Lukens Creek land-cover categories derived from ALSM. ....................................................................22 Figure 13. Bird Creek land-cover categories derived from ALSM. .........................................................................23 Figure 14. Waccasassa River land-cover categories derived from ALSM. ..........................................................24 Figure 15. ALSM-derived shoreline compared to 1:24,000 hydrography (USGS) shoreline at Bird Creek.......26 Figure 16. Transect A-A1 across Lukens Creek showing profile derived from bare-earth and canopy- surface models..................................................................................................................................................................28 Figure 17. Transect B-B1 showing profile from Lukens Creek across tidal marsh and forest remnants.........29 Figure 18. Transect C-C1 showing profile from upper reach of Lukens Creek to forest and relict dunes. .....30 Figure 19. Transect D-D1 showing profile from Waccasassa River to a meander on Bird Creek....................31 iii Photos 1. Low marsh at Site 1, Lukens Creek. ............................................................................................................................4 2. Black needlerush at Site 2, Bird Creek ......................................................................................................................4 3. Coastal forest at Site 3, Waccasassa River ..............................................................................................................5 4. Differential GPS roving antenna in high marsh at Lukens Creek..........................................................................6 5. Roving antenna and geodimeter in black-needlerush marsh ...............................................................................6 6. Transition from tidal marsh to forest at Bird Creek ...............................................................................................11 7. Morbid forest with standing dead Sabal palms at Lukens Creek .......................................................................11 8. Bird Creek levee with scrub and coastal-forest vegetation.................................................................................15 9. Sinkhole and sawgrass at Lukens Creek .................................................................................................................15 10. Thick sawgrass along tidal-creek tributary to Waccasassa River ...................................................................16 11. Tall, thick-canopied hydric hammock in summer ...............................................................................................20 12. Open-canopy oak and palmetto scrub in sand hills.............................................................................................20 13. Recovery of sand-hill oak scrub following fire management............................................................................21