Coastal Zone Coastal Zone ModuleModule

Tiffany L. HepnerTiffany L. HepnerBureau 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

Texas High School Coastal Texas High School Coastal Monitoring ProgramMonitoring 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.

Texas High School Coastal Texas High School Coastal Monitoring ProgramMonitoring Program

Provide high school students with an inquiry-based learning experience.

Increase public awareness and understanding of coastal processes and hazards.

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/

Gulf of Mexico

Galveston Bay

Matagorda Bay

San Antonio Bay

Copano Bay

Corpus Christi Bay

Baffin Bay

Laguna Madre

Ball High SchoolGalveston Island

Port Aransas High SchoolMustang Island

Port Isabel High SchoolSouth Padre Island

N

50 0 50 100 Kilometers

Study Area

TEXAS

Study AreaStudy Area

Student OrientationStudent Orientation

Beach MeasurementsBeach 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 rods Tape measure (at least 5m)Hand sighting level Survey flagsSighting compassData forms and clipboard

Topographic ProfileTopographic ProfileDetermine vertical changebetween front and back Emoryrods using siting level or horizon

Measure horizontal distancebetween Emory rods

-50 -25 0 25 50 75 100 125 150 175 200D istance

-4

-2

0

2R

elat

ive

heig

ht (

m) 1999 N ov 4

2000 S ep 21

2000 N ov 9

2001 F eb 1

vertica l exaggera tion = 10 :1

-50 -25 0 25 50 75 100 125 150 175 200D istance (m )

-4

-2

0

2

Rel

ativ

e he

ight

(m

) 2001 A pr 9

2001 O ct 2

2002 M ar 19

2002 O ct 11

vertica l exaggera tion = 10:1

M U I01 (M ustang Island)

M U I01 (M ustang Island)

Processes measurementsProcesses measurementsEstimates 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 measure Sighting compasswind gauge 3 floatsData forms and clipboard

Measuring Speed and Direction of CurrentOrientation of Dunes

and Shoreline

Observation of waves Observation of wind

Beach ObservationsBeach Observations

Shoreline MeasurementsShoreline 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 rods Digital camera

Sighting level Sighting Compass

Tape measure Data forms and clipboard

Mapping Shoreline and Vegetation Mapping Shoreline and Vegetation Line with GPSLine with GPS

2002-2003 Student Participants2002-2003 Student Participants

Beach FeaturesBeach Features

Barrier Island SystemBarrier Island System

Barrier Island Cross-SectionBarrier Island Cross-Section

Tropical Storm FrancesTropical Storm Frances

Tropical Storm FrancesTropical Storm Frances

September 7-13, 1998

Extensive beach and dune erosion and damage to structures.

Storm surge peaked at 1.4 meters above mean sea level.

Peak wave height = 4.09 meters

Extreme water levels (>0.78 meters) lasted 64 hours and extreme wave heights (>2.3 meters) lasted 73 hours.

Ball High School Monitoring SitesBall High School Monitoring Sites

BEG02 Pre-Tropical Storm FrancesBEG02 Pre-Tropical Storm Frances

BEG02 Post-Tropical Storm FrancesBEG02 Post-Tropical Storm Frances

Coastal ProcessesCoastal Processes

WavesWaves

There are 3 forces that form waves: wind, earthquakes, and gravitational attractions between Earth, Sun, and Moon.

Ocean waves are typically formed by the wind (friction between the wind and the waters surface).

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).

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.

Wave Length

Calm water level

WaveHeight

Crest

Trough

Wave DiagramWave Diagram

Wave Period = time it takes 2 successive crests (or troughs)to pass a fixed pointFrequency = number of waves per second (1/period)

Wave MotionWave Motion

Water particles in waves move in a nearly stationary circular motion.

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.

Breaking occurs when crest angle is less than 120º or a steepness (H/L) greater than 1/7.

Direction of wave

Seafloor

Breaker TypesBreaker Types

Spilling Breaker-gentle beach slope, waves break far from shore and surf gently rolls over the front of the wave

Plunging Breaker-moderately steep beach slope, less steep wave, slightly longer period, wave curls over forming a tunnel until wave breaks

Surging Breaker-steep beach slope, low wave of long period, doesn’t actually break-wave rolls onto beach

TidesTides

Tides are actually waves. They are caused by the gravitational forces of the Earth, Moon, and Sun.

Tides are caused by a relationship between mass of the above celestial objects as well as their distance from Earth.

The moon orbits the Earth once every 27 days and 8 hours. Therefore, the tides move up 50 minutes every day.

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.

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.

Neap tides occur when the moon is in the first and third quarter (tidal range smallest).

Galveston Pleasure PierGalveston Pleasure Pier

Neap

Neap

Spring

Spring

Galveston Pleasure Pier-June 2003Galveston Pleasure Pier-June 2003

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

152 157 162 167 172 177 182

Julian Day

Hei

ght A

bove

Mea

n Lo

wer

Low

Wat

er (

m)

Predicted

Observed

Hurricane Claudette Water LevelsHurricane Claudette Water Levels Corpus Christi July 10-20, 2003Corpus Christi July 10-20, 2003

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

190 192 194 196 198 200 202 204

Julian Day

Hei

ght

Abo

ve M

ean

Low

er L

ow W

ater

(m

)

Bob Hall Pier

Texas State Aquarium