This document summarizes ongoing projects to map historical shoreline change in Washington County, Rhode Island and project future shoreline positions. It discusses updating shoreline change maps from 1939 to 2014 and using statistical and process-based models to project shorelines as far as 2100 under scenarios of historic rates of change and increased rates due to sea level rise and increased storm impacts. The goals are to better understand coastal risk and guide sustainable development.

1. Shoreline Change Mapping (UPDATE)
and Projecting Future Shoreline change
Bryan A. Oakley1, Rob Hollis, 2,3, Emily Patrolia4
and Jon C. Boothroyd2,3* (deceased)
1. Dept. of Environmental Earth Science, Eastern Connecticut State University
2. Rhode Island Geological Survey
3. Dept. of Geosciences, University of Rhode Island
4. Department of Marine Affairs, University of Rhode Island

2. SHORELINE CHANGE SAMP:
ON-GOING PROJECTS
• Update (to include 2014) Shoreline Change Maps for
Washington County (HUD and RIBRWCT Funded)
• Project future shoreline change for the South Shore
(NOAA PSM Funding)

3. Updated 1939 – 2014 Shoreline Change Maps

4. Shoreline Change Maps
Understand Risk
www.BeachSAMP.org
http://www.crmc.ri.gov/maps.html

5. SCE m
Seaward Shoreline year − Landward Shoreline year
Net Shoreline Movement vs. Shoreline Change Envelope
Boothroyd et al., 2016
Boothroyd and Hehre, 2007
NSM (m
Years between oldest and youngest shoreline

6. Net Shoreline Movement (NSM)
1939
Shoreline
1951
Shoreline
2014
Shoreline
Shoreline Change Envelope (SCE)
1939
Shoreline
1951
Shoreline
2014
Shoreline
-37.5 m 63 m
EPR Rate =
Net Shoreline Movement
Number of years between
oldest and youngest shorelines
EPR Rate =
-37.5 m
75 years
EPR Rate = -0.5 m yr-1
SCE Rate =
63 m
-63 years
SCE Rate = -1.0 m yr-1
SCE Rate =
Distance between most
landward
and seaward shorelines
Landward year - seaward
year
Net Shoreline Movement vs. Shoreline Change Envelope

7. 1939
1963
1963
1939
2014
2012

9. Fill placed at
Quonset Point

10. Shoreline Type Average Shoreline
Change Distance (m)
Average Shoreline
Change Rate (m yr-1)
Shoreline Type %
Glacial Stratified -49.27 -0.76 6%
Barrier/ Beach -35.89 -0.57 63%
Glacial Till -18.41 -0.31 31%
Barrier/ Beach -15.50 -0.21 15%
Glacial Till -13.65 -0.20 11%
Glacial Stratified -8.71 -0.12 22%
Napatree Point to Point Judith
Point Judith to Potowomut River

11. 2016 Mapping vs. 2006 Mapping

12. Bousquet and Son – Aerial Views
Quonochontaug Barrier Pre/Post Sandy:
Barrier Spit Migration

13. PROJECTED FUTURE SHORELINE
POSITIONS
Matunuck Headland in 2050?
1951
2014

14. PROJECTING FUTURE SHORELINE CHANGE
i.e. Making a prediction on future shoreline position
in the future
• ‘Statistical based’ – take historic rates of shoreline change
and multiply them forward by the desired number of years
• ‘Process based’ – incorporate the historical observations,
coupled with physical conditions (grain size, wave
characteristics etc.) and models of beach evolution to
predict shoreline change

15. PROJECTING FUTURE SHORELINE CHANGE
• Increasing rates of shoreline change with
increasing rates of sea-level rise remain a
complicated and controversial topic…
• Significant debate still exists about whether
storms (Fenster et al., 2001; Morton, 2008; Morton
and Sallenger, 2003) or sea-level rise (Leatherman
et al., 2000; Zhang, 2002; Moore, 2006) drives
shoreline change.

16. PROJECTING FUTURE SHORELINE CHANGE
• Occam's razor suggests that while shoreline
change is driven by storms, higher rates of sea
level rise WILL produce higher rates of shoreline
change as storms are allowed to act higher on the
shoreline.
???

17. PROJECTING FUTURE SHORELINE CHANGE
• Our approach; present three scenarios at 2040, 2065 and
2100:
• Historic rate of change + uncertainty in shoreline position
(Ea)
• Exponential rate of Shoreline Change + uncertainty in
shoreline position (Ea)
• “Low” Scenario – rate of shoreline change doubles by
2100
• “High” Scenario – rate of shoreline change increases by
2.5X by 2065 (1 m of SLR) (Moore et al., 2007; Anderson et al., 2015)

18. Historic Rate
Exponential Low
(Double by 2100)
Exponential High
(2.5X by 2065)
Historical vs. Exponential Shoreline Change

19. Shoreline Position - 1939
Shoreline Position - 2014
Uncertainty
Annualized Rate: -1 m yr-1
Projecting Future Shorelines Based on
Historical Shoreline change
Shoreline Position - 2065
54 m (51 m + Uncertainty))
75 m 1939 – 2014

20. Shoreline Position - 1939
Shoreline Position - 2014
Uncertainty
Annualized Rate: -1 m yr-1
Projecting Future Shorelines Using
Exponential Shoreline change
Shoreline Position - 2065 86 m (Exponential High)
65 m (Exponential Low)
54 m (Historic)

21. Shoreline Position - 1939
Shoreline Position - 2014
Uncertainty
Annualized Rate: -1 m yr-1
Projecting Future Shorelines Using
Exponential Shoreline change
Shoreline Position - 2065
Coastal Setback- 2065

22. Misquamicut Barrier – 2100 – Historical Rate of Shoreline Change
Shoreline Position
Controlling Coastal Feature
Setback

23. Misquamicut Barrier – 2100 – Exp. High Rate of Shoreline Change
Shoreline Position
Controlling Coastal Feature
Setback

24. Undoubtedly, our understanding of the dynamics of
shoreline change in the face of accelerated sea level
rise will improve in coming years.
The goal of these projections is to inform
stakeholders and guide sustainable development
choices in the coming decade(s)
“Qualitative Modelling”
Exponential High…?

26. (Former) Boardwalk at SK-TB
Oct 2005
S. Kingstown Town Beach – October 2005 Extra-tropical storm
Bluff
Edge

27. Glacial Bluff at SK-TB Post Sandy
RIDOT
Boardwalk
Pilings

28. South Kingstown Town Beach Bluff Retreat
29 meters (95 feet) of retreat in 26 years

29. Matunuck Headland circa 1950
CRMC Archives

30. Matunuck, 1991 – CRMC Archives, J. Freedman

31. Matunuck, August 2013

32. North Carolina: 125,000 yBP
Sea Level + 6 m (20 ft)
Riggs et al., 2011
i.e. This was all
Underwater…

34. North Carolina:
A few decades and a major storm or two….
Riggs et al., 2011
East Beach, RI…….

35. North Carolina: 100-300 years in the future…?
Riggs et al., 2011

36. End of presentation
OakleyB (at) easternct.edu
http://www1.easternct.edu/oakleyb
http://www.beachsamp.org
Funders/Partners