1. Section 9: Extracting a Shoreline from Lidar Data

2. Historical Aerial Photography ( Provides Historical Shoreline Positions) 1930’s to 1990’s - Vertical Aerial Photographs

3. Shoreline Interpretation on Photography ( Wet/Dry Line) Gulf of Mexico Matagorda Bay

4. MHHW+0.6 m msl Geotube Landward boundary BEG-02 Beach profile QAd496Gibeaut_CCC_Jan31_2002 Lidar Digital Elevation Model (1 - m Grid) Ellipsoidal heights converted to orthometric heights (NAVD 88) using GEOID99 gravity model. Local mean sea level (MSL) correction applied.

5. Lidar Survey Video

6. Galveston Beach Wet/Dry Line

7. Intensity Draped on Topography

8. Galveston Island Profile

9. Representative Wet/Dry Elevation 0.6 m along Upper Tx Gulf Coast 0 1 2 3 -2 0.6 MHHW 0 100 Height relative to MSL (m) Distance (m) 50 upper berm crest vegetation line

10. Why Use a Wet/Dry 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.

11. Hand-Smoothed Shoreline