Coastal Processes 101. Greg Berman (Woods Hole Sea Grant & Cape Cod Cooperative Extension)

Transcription

1 Coastal Processes 101 Greg Berman (Woods Hole Sea Grant & Cape Cod Cooperative Extension) January 23, 2019

2 Coastal Processes 101 Outline: ~30 min talk Coastal Processes What is Erosion? Value of the Ecosystem Services

3 Glacial History 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 (Shaw et al., 2002)

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5 Coastal Processes

6 General Coastal Processes

7 Daily/Seasonal Variability Beach Profile Adjustments Large waves, which tend to occur in the winter in Massachusetts, cause the beach to temporarily change its profile. Winter Summer Images adapted from Natural Hazard Considerations for Purchasing Coastal Real Estate in Hawaii - A Practical Guide of Common Questions and Answers, by University of Hawaii Sea Grant College Program, 2006.

8 Beach loss eventually occurs in front of a seawall for a beach experiencing net longterm retreat. A beach undergoing net longterm retreat will maintain its natural width. Images adapted from Natural Hazard Considerations for Purchasing Coastal Real Estate in Hawaii - A Practical Guide of Common Questions and Answers, by University of Hawaii Sea Grant College Program, 2006.

9 Seasonal VS Long Term Erosion

10 Seasonal VS Long Term Erosion

11 Seasonal VS Long Term Erosion

12 Seasonal VS Long Term Erosion

13 Seasonal VS Long Term Erosion

14 Seasonal VS Long Term Erosion

15 Seasonal VS Long Term Erosion

16 Seasonal VS Long Term Erosion

17 Barrier Beach Town Beach Perpendicular to Shore 1 st appeared as ridges (far out on continental shelf) flooded by SLR Rising SL breaches the beach ridge and floods behind creating a bay. System migrates landward across the shelf and SL as rises.

18 Coastal Processes: Barrier Migration Perpendicular to Shore Overwash: Storms push sand across the island and into the lagoon area beyond. Barrier `rolls over on itself.

19 Coastal Processes: Barrier Migration Perpendicular to Shore Adapted from

20 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. General Coastal Processes

21 Evidence of Coastal Processes Transgressive = a beach migrating landward and upward, covering the water body or salt marsh that lies behind it.

22 General Coastal Processes

23 Longshore Sediment Transport

24 Longshore Sediment Transport

25 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.

26 What is Erosion?

27 The Erosion Problem: Education Perspectives It s all sediment transport! What is Erosion???... just more leaving than coming in Accretion Dynamic Equilibrium Erosion

28 Parallel Transport.Blocked LST +3 /yr +4 /yr +5 /yr +8 /yr -2 /yr -2 /yr -1 /yr 0 /yr Direction of Longshore Current Direction of Longshore Current Deposition Erosion Coastal Structure Downdrift Source: MORIS: CZM s Online Mapping Tool

29 Perpendicular Transport.Blocked input 1.3mi

30 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.

31 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

32 Natural Heritage and Endangered Species Program The Natural Heritage & Endangered Species Program (NHESP), part of the DFW, is responsible for the conservation and protection of hundreds of species that are not hunted, fished, trapped, or commercially harvested in the state. The Program's highest priority is protecting the 176 species of vertebrate and invertebrate animals and 259 species of native plants that are officially listed as Endangered, Threatened or of Special Concern in Massachusetts. State: Potential Habitat = historic and currently acceptable habitat Towns: Potential Habit = historic habitat

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34 Erosion Control Structures Designed to extend the usable life of a property. General practice 1920s 1950s. Scientists wrote letter in 1970 s... MA needs erosion. 310 CMR 10: no new coastal engineering structure on a coastal beach/dune/bank to protect a structure built after 8/10/1978 Towns: Engineered structures may require nourishment

35 Value of the Ecosystem Services

36 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes Barrier Beaches Coastal Banks SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, OR PROTECTION OF WILDLIFE HABITAT and/or MARINE FISHERIES Below MLW Rocky Intertidal Shores Salt Marshes

37 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes Barrier Beaches Coastal Banks SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, OR PROTECTION OF WILDLIFE HABITAT and/or MARINE FISHERIES MLW to Toe of Dune/Bank Rocky Intertidal Shores Salt Marshes

38 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, OR PROTECTION OF WILDLIFE HABITAT Barrier Beaches Coastal Banks Rocky Intertidal Shores Salt Marshes

39 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, OR PROTECTION OF WILDLIFE HABITAT and/or MARINE FISHERIES Barrier Beaches Coastal Banks Rocky Intertidal Shores Salt Marshes

40 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes Barrier Beaches Coastal Banks Rocky Intertidal Shores Salt Marshes SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, BECAUSE IT SUPPLIES SEDIMENT TO COASTAL BEACHES, COASTAL DUNES OR BARRIER BEACHES SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, BECAUSE IT IS A VERTICAL BUFFER TO STORM WATERS

41 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes SIGNIFICANT TO STORM DAMAGE PREVENTION, FLOOD CONTROL, OR PROTECTION OF WILDLIFE HABITAT and/or MARINE FISHERIES Barrier Beaches Coastal Banks Rocky Intertidal Shores Salt Marshes

42 Wetlands Protection Act CMR 10 Land Under the Ocean Coastal Beaches Coastal Dunes Barrier Beaches SIGNIFICANT TO THE PROTECTION OF MARINE FISHERIES, THE PREVENTION OF POLLUTION, STORM DAMAGE PREVENTION OR GROUND WATER SUPPLY Coastal Banks Rocky Intertidal Shores Salt Marshes

43 Value of the Ecosystem Services Coastal Property Owner Coastal Resource User Preserve upland Preserve CRA width Revetment Green Infrastructure Nourishment trigger at local beach elevation Nourishment is annual volume for downdrift beaches

44 Value of the Ecosystem Services Grandfathering.pre/post 1978 Buyer beware Remove grandfathering or drop the 1978 restriction on CES Right now we ve got 2 classes of property NFIP tried to remove grandfathering BW12 Lose grandfathering on change in ownership (2 nd homes 1 st )

45 WHAT STRATEGIES INCREASE COASTAL RESILIENCY ON CAPE COD?

46 Hazards --- Adaptation ADAPTATION STRATEGIES HA ZARDS P R O T E C T A C C O M M O D AT E R E T R E AT

47 Collect and organize information on the spectrum of resiliency strategies available A Spectrum Spectrum of Adaptation Strategies DO NOTHING? BEACH NOURISHMENT? OFFSHORE REEFS? COASTAL ARMORING?

48 Do nothing Vegetation Re-grade Managed retreat Beach nourishment Sand fencing Fiber rolls Coir Envelopes C E S Groin The Spectrum of Coastal Erosion Control Methods Sand Bags Gabion Breakwater / Sill Revetment Jetty Seawall

49 Do nothing Vegetation Re-grade Managed retreat Beach nourishment Sand fencing Fiber rolls Coir Envelopes C E S Groin The Spectrum of Coastal Erosion Control Methods Sand Bags Gabion Breakwater / Sill Revetment Jetty Seawall

50 The Spectrum of Coastal Erosion Control Methods Do nothing Vegetation Re-grade Managed retreat Beach nourishment Sand fencing Fiber rolls Coir Envelopes C E S WPA: Coastal engineering structure means, but is not limited to, any breakwater, bulkhead, groin, jetty, revetment, seawall, weir, riprap or any other structure that is designed to alter wave, tidal or sediment transport processes in order to protect inland or upland structures from the effects of such processes.

51 Do nothing The Spectrum of Coastal Erosion Control Methods 1. Will system recover by itself? 2. How far is the structure from the water? 3. Grandfathering protects structures (not lawn) before August 10, 1978 Photo Credit: Ann McNichol

52 The Spectrum of Coastal Erosion Control Methods Do nothing Vegetation Re-grade Managed retreat Horizontal V E R T I C A L

53 Adaptation - Brewster 09/29/ /15/ /12/2017

54 Questions? Greg Berman Coastal Processes Specialist Woods Hole Sea Grant Cape Cod Cooperative Extension

55 About this analysis The maps shown here combine two existing datasets: Zones of chronic inundation along the coast, previously published by Dahl et al and Spanger-Siegfried et al and included in the analysis and accompanying interactive maps for When Rising Seas Hit Home: Hard Choices Ahead for Hundreds of US Coastal Communities (2017) The Zillow Transaction and Assessment Database (ZTRAX), published by the online real estate company Zillow (Zillow 2017). The findings presented here are intended to be a starting point for community, state, and national-level discussions about the risks of sea level rise to coastal property. Where possible, communities should undertake more detailed local mapping in order to better assess their specific risks.

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