Peter A. Slovinsky, Marine Geologist Maine Geological Survey Department of Agriculture, Conserva=on and Forestry. Funding from:

Transcription

1 Peter A. Slovinsky, Marine Geologist Maine Geological Survey Department of Agriculture, Conserva=on and Forestry Funding from:

2 50% 40% Figure modified from Griggs, %

3 Global Sea Level Rise Driving Factors: Volumetric Increase (mel=ng of land-based ice sheets and glaciers) Glaciers (m of water equivalent thickness) 30 well-studied glaciers have decreased in average thickness by 60 feet

4 Global Sea Level Rise Driving Factors: Thermal Expansion (expansion of the water column due hea=ng of the oceans) Ocean Heat (10 22 joules) compared with average Global sea level (mm) as difference from 1990 Global sea level rise average over the last century: 1.8 mm/year

5 Since 1993, global sea level has risen at 3.4 mm/yr

6 Locally, sea level is rising in the long term

7 is rising faster in the short term can rise abruptly

8 Abrupt short-term sea level rise in the North AtlanPc Portland saw an average of approximately 5 higher than normal Pdes in the summer of 2009, and, especially in winter of This was the highest along the whole east coast.

9 Causes: 1) A downturn (or slow-down) of the AtlanPc Meridional Overturning CirculaPon (AMOC) Image from dailymail.co.uk

10 Causes: 2) A strongly negapve North AtlanPc OscillaPon Cold air dips south Northeasters track up coast Weakened westerly winds allow for dominant onshore winds

11 Five of the highest monthly sea levels recorded occurred in 2010 Nine of the highest monthly sea levels occurred in the last decade

12 and is expected to con$nue to rise.

13 FEMA Flood Insurance Rate Maps are changing

14 and in general, flood zones are expanding and are increasing in height.

15 King Tide October 25, 2016 A. Sherwin, MCP I m going to need a boat soon

16 Hourly Readings >= 12 b MLLW Long Term Mean Last Decade Mean Exis=ng Condi=ons (flood stage = 12 ^ MLLW) Long Term Mean = 2.6 readings/year Last Decade Mean = 8.5 readings/year Data from NOAA CO-OPS

17 Changes in Annual Flooding DuraPon with SLR (using 2013 as a representapve year) Scenario Flood Stage (ft, MLLW) # times inundated % of high tides Duration, hrs Existing Flood % ft SLR % ft SLR % ft SLR % ft SLR % based on 2013 Portland tidal station data from the NOAA Inundation Analysis Tool Based on this, there would poten=ally be a tenfold increase in the frequency of flooding with one foot of sea level rise.

18 What about storm Pdes and storm surges?

19 Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical Pdes. Storm surge should not be confused with storm =de, which is defined as the water level rise due to the combina=on of storm surge and the astronomical =de (Na=onal Hurricane Center)

20 Storm Surge Superstorm Sandy Kings Point, NY 10/29-10/30/2012 Storm Tide Predicted Storm Surge

21 Storm Surge Superstorm Sandy Predicted Storm Tide Portland, ME 10/29-10/30/2012 Storm Surge

22 Time Interval (years) Surge Height (feet) (100 %) 2 (50%) (20%) 3.3 (10 %) (5%) (4 %) (2 %) (1.3 %) 6.0 (1%) These numbers correlate rela$vely well with overall longer term sea level rise planning! P.A. Slovinsky, MGS

23 Interval (yrs) High Storm Water Tide Level (b, (ft, MLLW) MLLW) 1 5 (100 %) (20%) (10 %) (4 %) (2 %) (1 %)

24 Interval (yrs) High Storm Water Tide Level (b, (ft, MLLW) MLLW) 1 5 (100 %) (20%) (10 %) (4 %) 1 foot difference! (2 %) (1 %)

25 And complicapng all this is precipita$on 100-year 24-hour rainfall has increased by about 25-30% (TP-40 to Atlas 14) Brunswick Public Works Wmtw.com 4.8 of rain (within 6 hours between a 50 and 100-year event!) and an 11.6 G $de with 0.5 G of surge! Portland Press Herald C. Adams, MGS

26 MGS has created many state-wide GIS datasets to support municipal resiliency to coastal hazards and climate adaptapon Viewers or datasets created: Highest Annual Tide (HAT) line PotenPal sea level rise and storm surge inundapon Sea Lake and Overland Surges from Hurricanes (SLOSH) Shoreline Change (under way) Coastal Sand Dune Maps Landslide Hazard and Coastal Bluff Stability Maps Poten=al Marsh Migra=on Living shoreline suitability (under way) hgp://

27 The Highest Annual Tide (HAT) is the regulatory boundary for Shoreland Zoning in =dal areas. hgp://

28 Unlike most viewers, uses the Highest Annual Tide (HAT) as a star=ng point. hgp://

29 hgp://

30 Category 2 at Mean High Tide hgp://

31 Source: NH Science and Technical Advisory Panel (STAP), 2014 PotenPal Planning Thresholds and Horizons Recommended Planning for Sea Level Rise: Short Term: approximately 1 ^ by 2050 Long Term: 3.3 ^ or more by 2100

32 PotenPal Planning Thresholds and Horizons Sea level rise will likely exacerbate the frequency, duration, and extent of flooding due to storm surge. Recommended Planning for Storm Surge: Consider use of the Federal Flood Resiliency Management Standard per Execu=ve Order for infrastructure BFE+2, BFE+3 0.2% Eleva=on Use a climate informed science approach

33 PotenPal Planning Thresholds and Horizons Sea level rise will likely exacerbate the frequency, duration, and extent of flooding due to storm surge. Recommended Planning for Storm Surge: Add SLR scenarios to current 1% and 0.2% flood elevarons from best-available flood data (NHSTAP, 2014)

34 ComplicaPng all this Climate Change will likely exacerbate the frequency and amount of precipitation that falls Recommended Planning for PrecipitaPon: For current design, use the best available precipita$on informa$on such as NOAA ATLAS 14 or NRCC precipita$on data hvp://hdsc.nws.noaa.gov/hdsc/pfds/ hvp://precip.eas.cornell.edu/ Design to manage a 15% increase in frequency ager 2050 (NH STAP)

35 Thank you! Peter A. Slovinsky, Marine Geologist Maine Geological Survey (207)