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Coastal Zone Module Tiffany L. Hepner Bureau of Economic Geology John A. and Katherine Jackson School of Geosciences The University of Texas at Austin Development of this module has been funded by National Science Foundation Geoscience Education GEO-0224501
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Texas High School Coastal Monitoring Program Funding for THSCMP is provided by the Texas Coastal Coordination Council, The Meadows Foundation, the National Science Foundation, Conoco, the Exxon Foundation, and the Wray Family Trust.
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Texas High School Coastal Monitoring Program l Provide high school students with an inquiry-based learning experience. l Increase public awareness and understanding of coastal processes and hazards. l Obtain a better understanding of the relationship between coastal processes, beach morphology, and shoreline change, and make data and findings available for solving coastal management problems. http://txcoast.beg.utexas.edu/thscmp/
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Study Area
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Student Orientation
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Beach Measurements Topographic transect oriented perpendicular to the shoreline. For comparison through time, profiles are measured from the same starting point landward of the beach and oriented in the same direction. Purpose: Provide quantitative morphological data and shoreline and vegetation line positions Method: Measure relative changes in beach topography using Emery rods and tape measure Equipment: Emery rodsTape measure (at least 5m) Hand sighting levelSurvey flags Sighting compassData forms and clipboard
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Topographic Profile Determine vertical change between front and back Emory rods using siting level or horizon Measure horizontal distance between Emory rods
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Processes measurements Estimates of processes acting on the beach: wind direction and speed; wave breaker type; surf zone width; wave direction, height, and period; number of apparent longshore bars; longshore current Purpose: Explore relationship between processes and beach changes. Over time these data may be used to “calibrate”, for a specific beach location, data acquired by weather and wave stations in the area. Encourage students to systematically observe processes that surround them Method: Visual observations averaged among three observers. Float and stopwatch for longshore current. Hand-held wind gauge Equipment: Tape measureSighting compass wind gauge3 floats Data forms and clipboard
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Measuring Speed and Direction of Current Orientation of Dunes and Shoreline Observation of waves Observation of wind Beach Observations
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Shoreline Measurements Horizontal (no elevation) survey of the vegetation line and shoreline. Shoreline and foredune trends. Measurement of beach cusps Purpose: Provide quantitative data on the position and trend of the shoreline and the longshore spacing and relief of beach cusps Method: Differential Global Positioning System walking survey Equipment: Differential Global Positioning System (GPS) receiver Emery rodsDigital camera Sighting levelSighting Compass Tape measureData forms and clipboard
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Mapping Shoreline and Vegetation Line with GPS
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2002-2003 Student Participants
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Beach Features
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Barrier Island System
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Barrier Island Cross-Section
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Tropical Storm Frances
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l September 7-13, 1998 l Extensive beach and dune erosion and damage to structures. l Storm surge peaked at 1.4 meters above mean sea level. l Peak wave height = 4.09 meters l Extreme water levels (>0.78 meters) lasted 64 hours and extreme wave heights (>2.3 meters) lasted 73 hours.
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Ball High School Monitoring Sites
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BEG02 Pre-Tropical Storm Frances
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BEG02 Post-Tropical Storm Frances
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Coastal Processes
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Waves l There are 3 forces that form waves: wind, earthquakes, and gravitational attractions between Earth, Sun, and Moon. l Ocean waves are typically formed by the wind (friction between the wind and the waters surface). l The size of a wave depends upon the wind speed, length of time wind blows in the same direction, and the fetch (distance over which the wind blows). l Wind waves will continue as long as the wind is blowing. Once the wind stops the waves will continue until all of their energy is dissipated.
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Wave Length Calm water level Wave Height Crest Trough Wave Diagram Wave Period = time it takes 2 successive crests (or troughs) to pass a fixed point Frequency = number of waves per second (1/period)
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Wave Motion l Water particles in waves move in a nearly stationary circular motion. l At the surface, the orbit is ~ equal to the wave height. The orbits decreases in size downward through water column to a depth of L/2. l Breaking occurs when crest angle is less than 120º or a steepness (H/L) greater than 1/7. Direction of wave Seafloor
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Breaker Types l Spilling Breaker-gentle beach slope, waves break far from shore and surf gently rolls over the front of the wave l Plunging Breaker-moderately steep beach slope, less steep wave, slightly longer period, wave curls over forming a tunnel until wave breaks l Surging Breaker-steep beach slope, low wave of long period, doesn’t actually break-wave rolls onto beach
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Tides l Tides are actually waves. They are caused by the gravitational forces of the Earth, Moon, and Sun. l Tides are caused by a relationship between mass of the above celestial objects as well as their distance from Earth. l The moon orbits the Earth once every 27 days and 8 hours. Therefore, the tides move up 50 minutes every day. l High tide is generated by the pull of the moon upon global waters. There is an equal pull on the opposite side of the Earth from the moon. l Spring tides occur when the Earth, sun, and moon line up (new and full moon-2x during the lunar month). Spring tides have the largest tidal ranges. l Neap tides occur when the moon is in the first and third quarter (tidal range smallest).
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Galveston Pleasure Pier Neap Spring
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Galveston Pleasure Pier-June 2003
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Hurricane Claudette Water Levels Corpus Christi July 10-20, 2003
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