1. Pg. 43 1.Shoreline is the boundary between ocean/lake and land 2.) Beach is the strip of sediment that extends from low tide inland to a cliff or zone of permanent vegetation 3.) Waves erode and deposit material along the shore erode-take away deposit-leave behind Courtesy of USGS

2. Pg. 43 4.Beach erosion is a geologic hazard - one that costs millions of dollars to prevent and control A. East coast - build on barrier islandsbarrier islands B. West coast - narrowing of beaches -sediments are being removed

3. Pg. 43 5. Where do wave get their energy? A. Wind B. Movement of sea floor - tsunami C. Landslides D. Volcanic explosion Waves transmit energy so they have capacity to do work As in “beaches and structures get ‘worked’ by waves”

4. Pg. 44 6. Characteristic features of waves A. Crest B. Trough C. Wavelength Tsunami - very long wavelength Winter - longer = move sand offshore Summer - shorter = move sand onshore D. Height

5. Image courtesy of Office of Naval Research. Another good link

6. Pg. 44 7. The height and length depend on 3 things A. Wind speed/strength B. Duration the wind has blown C. Fetch - the distance over which the wind has blown ROGUE WAVES are extra big (sink ships)WHY??? Constructive and destructive wave interaction

7. Pg. 44 8. How does the water within a wave move? A. Wave form moves forward, water particles move in a circular path B. At 1/2 the wavelength wavebase and lower there iswavebase negligible water motion above is when the wave touches bottom Courtesy of NOAA 1 wavelength Wavebase=1/2 wavelength

8. Pg. 44-45 9. This explains a number of things: A.Wave refraction - waves bend as they hit theWave refraction shoreline at angle. Leading edge reaches base level first and slows down. B.Waves break as they approach the shore remember wave base - surf C. Beach drift-movement of sediments down shore D. Longshore currents-causes longshore drift of sedimentsLongshore drift of sediments Another diagram of longshore current and thediagram resulting drift of sediments ND pg. 363 fig. 12.34

9. Pg. 44-45 9. This explains a number of things: continued E. ADD summer and winter beaches-constantly in flux THIS IS FOR HIGHER LATITUDES SUMMER DEPOSITION: short wavelength=pushes sand towards the beach=sandy beach WINTER EROSION: long wavelength=sand away from beach=rocky beach=sand is deposited off shore Illustrates that wave type influences beaches ND pg. 361/ fig. 12.30/12.31

10. Pg. 45 10.Were does the material come from that forms beaches? A. Shoreline erosion - nearby land or cliff-mass wasting Courtesy of NOAA Sediment production

11. Pg. 45 B. Erosion of the land - brought to ocean by streamsstreams Courtesy of NASA

12. Pg. 45 11. Waves erode by: A. Impact sediments bashing against stone creates more sediments - sand blaster B. Pressure-waves compress water into cracks=increases pressure=more cracking C. Abrasion-sediments sliding/grinding against stone creates more sediments - sand paper D. ADD physical removal of sediments already did but is important longshore offshore-winter vs. summer ND pg. 361 fig. 12.30 & 12.31

13. Pg. 45 12. Human Effects on Coast- Trying to Control Erosion A) Dams - store sediment behind - beaches diminished B) Sea Walls and riprap - to stop cliff retreatSea Walls riprap build on a cliff and consider it a temporary structure erosion will win-WHY wall REFLECTS larger waves ND pg. 354 fig. 12.22 *Creates deeper water which allows bigger waves to hit the wall and the wall reflects this larger amount of energy which takes sand out to sea/away=EROSION C) Groins - trap sand so won’t disappearGroins Still need artificial replacement (fig. 1)

14. Pg.45 (continued) D) Jetties - create protection for channels for boatsJetties E) Breakwater -protection for harbor, form tombolo(fig. 5)Breakwater F) Sea level rise ND pg. 353/ fig. 12.20Sea level rise Know: migration distance=1000(d) So if sea level rises 4 feet WHAT WILL HAPPEN? Direction of movement an amount So if sea level lowers 2 feet WHAT WILL HAPPEN? Direction of movement an amount

15. Pg. 46 BOTTOM LINE -YOU CAN’T CONTROL NATURE BEACH REPLENISHMENT is expensive and where do you get the sand?

16. Pg. 46 Mitigation generally falls into one of the following: 1)Beach nourishment-bring it in and dump it (imitates natural depositional processes) 2) Shoreline stabilization through structures see #12 3) Land-use changes-”uhm… maybe we shouldn’t build there” People need to understand that coastal zone development is temporary and expendable. Keep in mind these 5 principles…

17. Pg. 46 1)Coastal erosion is natural process problems occur when people build structures within the coastal zone 2) Any shoreline construction causes change 3) Stabilization through engineering structures protects the property of relatively few people at great expense to the general public. 4)Structures designed to protect a beach may eventually destroy it. 5)Once built, structures produce a trend in coastal development that is difficult to reverse.

18. QUIZ SLIDE #1 What is this feature? Which way is the longshore current/drift? SLIDE #2 How does this slide relate to beach erosion/deposition? SLIDE #3 What will be the results for each of the two pairs of waves SLIDE #4 Which wave represents summer and winter waves and WHY? Which wave will result in sand deposition and which erosion WHY HURRICANE REVIEW VIDEO?