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HomeMy Public PortalAbout160405_BCAG_MeetingSlidesBrewster Coastal Risks Yesterday, Today, and Tomorrow BCAG  –  Mee)ng  3   — For  Committee  consideration   — Local  Tides   — Historic  storm  surge  measurements  for   Nor’Easters   — Sea  Level  Rise  (SLR)  and  storm  surges  in  the   context  of  high  tides   — Coastal  Change  –  a  historic  perspective   — Updated  GIS  visualizations     — Preliminary  parking  impacts   2016  NOAA  )dal  predic)ons   Sesuit  Harbor,  East  Dennis,  MA   — Tidal  range  (consecutive  Low/High  Tides):   — Average:  10.3  feet   — Ranging  from  6.8  to  15.2  feet   — Relative  to  the  shoreline  (Mean  High  Water  or   MHW)   — Most  (58%)  high  tides  are  above  MHW   — ~  1  in  17  high  tides  (5.8%)  are  ≥2  ft  above  MHW:  that’s   41  high  tides   — 3  greatest  high  tides  are  2.8  feet  above  MHW   Measured  Historic  Storm  Surges   — Historic  Storm  Surges  from  NOAA’s  Boston   Gauge   — 4.21'  on  February  9,  2013  (Winter  Storm  Nemo)   — 4.57'  on  October  29,  2012  (Hurricane  Sandy)   — 4.88'  on  October  30,  1991  ("Perfect  Storm"  Halloween   Nor'easter)   — 4.34'  on  February  6,  1978  (Blizzard  of  1978)   — 3.69'  on  February  14,  1940  (Valentine's  Day  Nor'easter  )   — For  visualizations  purposes,  assume  4  ft  surge   SLR  Scenarios  –  Boston  Gauge   Source:  U.S.  Army  Corps  of  Engineers  (USACE)  Sea  Level  Change  Curve  Calculator,  Version  2015.46   — 1  ft  @2038  (in  ~20  years)   — 2  ft  @2054  (in  ~40  years)   — 4  ft  @2078  (in  ~60  years)   Scenarios   — Presented  at  BCAG  Meeting  2   — SLR:  2  ft  and  4  ft  above  MHW   — Storm  surges:  6  and  10  ft  (SLOSH  model)   — Requested  after  Meeting  2,  presented  here   — SLR:  2  ft  and  4  ft  above  MHW   — Storm  surge:  4  ft  (a  “Nor-­‐Easter”)   — To  put  things  into  perspective   — 2  ft  above  MHW  already  occurs  40  times  a  year   — 4  ft  SLR  is  a  daily  equivalent  to  a  Nor-­‐Easter   surge   Coastal Change A Historic Perspective at the Landings   — Breakwater  and  Little  Breakwater   — Paine’s  Creek   — Crosby   Breakwater and Little Breakwater Landings Town and State Owned Property Breakwater and Little Breakwater Landings 1994 Color Aerial and MA CZM Shoreline Breakwater and Little Breakwater Landings 2009 Color Aerial and MA CZM Shorelines Breakwater and Little Breakwater Landings 2014 Color Aerial and MA CZM Historic Shorelines Breakwater and Little Breakwater Landings Historic Shorelines, Erosion Rates and Variability Short Term: 3.05 ft/year (accretion) Long Term: -0.26 ft/year (erosion) Short Term: -1.41 ft/year (erosion) Long Term: -0.56 ft/year (erosion) 1951   1994   2009   1934   Paine’s Creek 2014 Color Aerial and MA CZM Historic Shorelines Crosby Landing 2014 Color Aerial and MA CZM Historic Shorelines Challenging  Predic)ons   — Large  variability   — Spatially   — Temporally   — Limited  data  (shorelines)   — Built  environment  has  changed   Updated  GIS  Flood  Visualiza)ons   — Paine’s  Creek,  Mant’s  Landing,  and  Wing   Island   — Linnell  and  Crosby  Landings   — Little  Breakwater  and  Breakwater   — Ellis  Landing     Paine’s Creek, Mant’s Landing, and Wing Island Salt & Fresh Water Wetlands, and Town Owned Land Paine’s Creek, Mant’s Landing, and Wing Island Mean High Water Paine’s Creek, Mant’s Landing, and Wing Island MHW + 2 feet Sea Level Rise Paine’s Creek, Mant’s Landing, and Wing Island MHW + 4 feet Sea Level Rise (or MHW + 4 foot Storm Surge – possible today) Paine’s Creek, Mant’s Landing, and Wing Island MHW + 4 ft SLR + 4 ft Storm Surge Paine’s Creek, Mant’s Landing, and Wing Island Flooding at Various SLR and Surge Levels Linnell and Crosby Landings Salt & Fresh Water Wetlands, and Town/State Owned Land Linnell and Crosby Landings Mean High Water Linnell and Crosby Landings MHW + 2 feet Sea Level Rise Linnell and Crosby Landings MHW + 4 feet Sea Level Rise (or MHW + 4 foot Storm Surge - possible today) Linnell and Crosby Landings MHW + 4 ft SLR + 4 ft Storm Surge Linnell and Crosby Landings Flooding at Various SLR and Surge Levels Little Breakwater and Breakwater Landings Salt & Fresh Water Wetlands, and Town Owned Land Little Breakwater and Breakwater Landings Mean High Water Little Breakwater and Breakwater Landings MHW + 2 feet Sea Level Rise Little Breakwater and Breakwater Landings MHW + 4 feet Sea Level Rise (or MHW + 4 foot Storm Surge - possible today) Little Breakwater and Breakwater Landings MHW + 4 ft SLR + 4 ft Storm Surge Little Breakwater and Breakwater Landings Flooding at Various SLR and Surge Levels Ellis Landing Salt & Fresh Water Wetlands, and Town Owned Land Ellis Landing Mean High Water Ellis Landing MHW + 2 feet Sea Level Rise Ellis Landing MHW + 4 feet Sea Level Rise (or MHW + 4 foot Storm Surge - possible today) Ellis Landing MHW + 4 ft SLR + 4 ft Storm Surge Ellis Landing Flooding at Various SLR and Surge Levels Paine’s  Creek  –  Access  Impacts   Paine’s  Creek  –  Access  Impacts   Preliminary  Impacts  to     Parking  and  Access   Coastal  Landing Parking  Spaces Scenarios  with  Impacts Parking  Access  to  Parking   Paines  Creek 19 4  ft  SLR 4  ft  SLR  +  4  ft  surge Mants 44 4  ft  SLR/surge 4  ft  SLR/surge Saints 38 N/A N/A Little  Breakwater 6 N/A 4  ft  SLR Breakwater 62 4  ft  SLR  +  4  ft  surge 4  ft  SLR  +  4  ft  surge Point  of  Rocks 3+8 N/A N/A Ellis 19 4  ft  SLR  +  4  ft  surge N/A Linnell 25 4  ft  SLR  +  4  ft  surge N/A Crosby 60 4  ft  SLR/surge 4  ft  SLR/surge Questions?   Paine’s Creek Town and State Owned Property Paine’s Creek 1994 Color Aerial and MA CZM Shoreline Paine’s Creek 2009 Color Aerial and MA CZM Shorelines Paine’s Creek 2014 Color Aerial and MA CZM Shorelines Crosby Landing Town and State Owned Property Crosby Landing 1994 Color Aerial and MA CZM Shoreline Crosby Landing 2009 Color Aerial and MA CZM Shorelines Crosby Landing 2014 Color Aerial and MA CZM Historic Shorelines