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Home My Public Portal AboutBrewster_Berman_15_17_2018Sediment Transport And The Effects of Rising Seas Greg Berman (Woods Hole Sea Grant & Cape Cod Cooperative Extension) May 17, 2018 Cape Cod Museum of Natural History. Outline: •~30 min talk & time for questions •How does sand move? •SLR •Coastal Threats (Existing/Future) Prepare for Flooding !!! No rush… I’ll cross that bridge when I come to it. Sediment Transport And The Effects of Rising Seas What is Erosion ? The Erosion Problem: Education Perspectives It’s all sediment transport! What is Erosion???..... just more leaving than coming in ErosionAccretionStatic Equilibrium General Coastal Processes Downdrift Direction of Longshore Current Coastal Structure Direction of Longshore Current Erosion Deposition +5’/yr+8’/yr +4’/yr+3’/yr -2’/yr -2’/yr 0’/yr -1’/yr Source: MORIS: CZM’s Online Mapping Tool Longshore Sediment Transport Longshore Sediment Transport Longshore Sediment Transport Longshore Sediment Transport Longshore Sediment Transport Longshore Sediment Transport Google Earth Engine: Timelapse is a global, zoomable video that lets you see how the Earth has changed over the past 32 years. It is made from 33 cloud-free annual mosaics, one for each year from 1984 to 2016, which are made interactively explorable by Carnegie Mellon University CREATE Lab's Time Machine library. Longshore Sediment Transport Google Earth Engine: Timelapse is a global, zoomable video that lets you see how the Earth has changed over the past 32 years. It is made from 33 cloud-free annual mosaics, one for each year from 1984 to 2016, which are made interactively explorable by Carnegie Mellon University CREATE Lab's Time Machine library. General Coastal Processes 1.3mi Perpendicular Transport…….Blocked input Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Seasonal VS Long Term Erosion Coastal Processes: Why they matter •70 –80% of MA shoreline is eroding •Erosion rates have increased since 1950’s •Erosion is not steady…punctuated by storms (layers exposed can cause slumping) Coastal Processes: Key Points 1.Erosion of glacial landforms is the MOST important source of sediment for dunes and beaches in Massachusetts. 2.Wind and waves then transport sediment. 3.Without erosion and then longshore re-deposition there would be no beaches. Coastal Processes: Key Points 1.Erosion of glacial landforms is the MOST important source of sediment for dunes and beaches in Massachusetts. 2.Wind and waves then transport sediment. 3.Without erosion and then longshore re-deposition there would be no beaches. Thanks for contributing sand to our coastal resource areas Thanks for contributing sand to our coastal resource areas Thanks for contributing sand to our coastal resource areas Climate VS Weather Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time. https://www.nasa.gov/mission_pages/noaa-n/climate/climate_weather.html Anyone younger than 40 has ONLY seen rising temperatures EVERY year (Shaw et al., 2002) 25,000 yr ago 400’ below SL, ~1 mile thick By ~ 15,000 ice was gone. 11,000 years ago 6,000 years ago Present Day Glacial History December 2013 Global ↑↑↑↑↑↑ ↓↓↓↓↓↓ Massachusetts State of MA Guidance State SLR Guidance State SLR Guidance 2 0 1 3 2 0 1 8 State SLR Guidance 2 0 1 3 2 0 1 8 Carol1938 10 year flood will be every other year (10% into 50%) Changing the return period of flooding Changing the return period of flooding 1.3’ 500 yr → 50 yr 100 yr →10 yr Hurricane Sandy We got lucky !!! http://www.heraldtribune.com/ 8 9 10 11 12 13 10/29/2012 Predicted high tides at Sesuit Harbor for 2012 2’ 0.1% Hurricane Sandy Battery, NY: 9.5’ surge Landfall >300 miles south, we still got 4½ feet surge Low Tide: 6pm http://www.heraldtribune.com/ 0.1% Hurricane Sandy Battery, NY: 9.5’ surge Landfall >300 miles south, we still got 4½ feet surge Low Tide: 6pm Peak Surge: 5pm 4½ feet High Tide Surge: 2½ feet http://www.heraldtribune.com/ 0.1% Hurricane Sandy VS Nor’Easter Nemo Low Tide: 6:00pm Peak Surge: 5:00pm 4½ feet Low Tide: 3:30am Peak Surge: 2:30am 4¼ feet Sandy 10/29-30/2012 Nemo 02/08-09/2013 Nor’Easter (January 2018) High Tide: 12:30pm Peak Surge: 12:30pm 3.1 feet 1/4-5/2018 Nor’Easter (January 2018) Hurricane Sandy (10/29-30/2012) Predicted High WL = 10.3 MLLW Actual High WL = 12.8 MLLW Nor'easter Nemo (2/8-2/9/2013) Predicted High WL = 10.0 MLLW Actual High WL = 13.0 MLLW Nor'easter Grayson (1/4-5/2018) Predicted High WL = 12.1 MLLW Actual WL = 15.2 MLLW Max Surge: 4.5’ High Tide Surge: 2.5’ Max Surge: 3.9’ High Tide Surge: 3.0’ Max Surge: 4.5’ High Tide Surge: 3.1’ In Boston, a storm tide of 15.16’ was recorded which beat the record set by the Blizzard of 1978 (15.0’). SL has risen ~4.5” in the 40 years since 1978….so SLR is the reason the record was broken!!! Nor’Easter (March 2018) Max Water Level: 15.16’Max Water Level: 14.54’ Still 2’ of surge 5 days later !!! Flood Event Waves Diff = 0.6’….. But 0.5’ is predicted tide Nor’Easter (March 2018) Nor’Easter (March 2018) 6,000 years ago 11,000 years ago (Shaw et al., 2002) 400’ below SL, ~1 mile thick Shoreline was >200 miles offshore present 15,000 years ago = No ice Sea level has risen for tens of thousands of years…it’s not stopping anytime soon, and it’s projected to accelerate. Regarding storms…we’ve been lucky for a long time. Need to plan/adapt “while the sun is shining”! Erosion & Flood management is going to become even more effective as costs + dangers ↑↑↑ http://www.heraldtribune.com/ 0.1% The Implications… Our Choices Matter !!! 2017 National Institute of Building Sciences (NIBS) study looked at 23 years of federally funded mitigation grants provided by the FEMA, EDA and HUD and found mitigation funding can save the nation $6 in future disaster costs, for every $1 spent on hazard mitigation. Original 2005 study had 4:1 ratio. Global Local$$ Questions? Greg Berman Coastal Processes Specialist Woods Hole Sea Grant | Cape Cod Cooperative Extension gberman@whoi.edu | gberman@barnstablecounty.org www.whoi.edu/seagrant www.capecodextension.org/ Extra Slides Greg Berman Coastal Processes Specialist Woods Hole Sea Grant | Cape Cod Cooperative Extension gberman@whoi.edu | gberman@barnstablecounty.org www.whoi.edu/seagrant www.capecodextension.org/ Overwash : Storms push sand across the island and into the lagoon area beyond. Barrier `rolls over on itself.‘ Barrier Migration General Coastal Processes Sea level rise has been occurring for thousands of years. During this time barrier beaches have migrated landward through natural coastal processes and have avoided “drowning in place”. Evidence of Coastal Processes “Transgressive” = a beach migrating landward and upward, covering the water body or salt marsh that lies behind it.