ASFPM 2012 Annual Conference Developing Coastal Erosion Hazard Area Maps for Lakes Ontario and Erie New York State Department of Environmental Conservation (DEC) Jeff Burm, CFM Elena Drei-Horgan, PhD, CFM Matt Chlebus (NYDEC) Brent McCarthy, PE, CFM
Agenda CEHA Program Methodology for developing the NPF and SHA Status of the Project 2
Coastal C Erosion E Hazard H Area A Program maintained by the New York State Department of Environmental Conservation Page 3
Why coastal erosion areas need to be protected? Beaches, dunes, bluffs, wetlands protect the coastal zone from waves, flooding and erosion Sediment reservoirs for shore stabilization Dynamic environments constantly changing Preserved for the future generations Page 4
How does DEC protect coastal areas? Natural and human activities along the coast are exposed to erosion risks Threats to life and properties can be reduced by regulating land use and development All NYS great lakes and coastal shorelines are regulated Coastal Hazard Erosion Areas Permit Program Article 34 Part 505 NYS ECL Page 5
Natural Protective Features Nearshore Beaches Dunes Bluffs Page 6
Why New, Why Now Page 7
Lake Eire and Lake Ontario Work Areas DEC tasked AECOM with a Pilot study to develop new approach Pilot study 8 mi: Towns of Porter and Wilson (Niagara Co) 1mi: Town of Ellisburg (Jefferson Co) Lake Eire Developed Maps for 30 mi Lake Ontario Entire NYS shoreline (approx. 200 mi) in Jefferson, Oswego, Cayuga, Wayne, Monroe, Orleans and Niagara counties Page 8
Transect-Based Approach Transects spaced 50 m Transects placement automated in GIS 2011 USACE Lidar topo/bathy data 2011 USACE Imagery 1978/1979 NYS historic imagery Page 9
The Accuracy of the Results Depends upon an Accurate Algorithm extracts and Approach fits a line between the point cloud bare-earth data Topo/bathy data extraction using USGS Matlab-based package (Plant et al., 2002- Stockdon et al., 2009) RMSE error is provided at each point along the transect Result is a profile for NPF Identification Page 10
NPFs Accuracy is Increased by Manual Selection of the Features Nearshore (automated) MLW (automated) Beach Seaward extent (automated) Landward extent (manual) Dune (manual) Toe, Crest, Heel Bluff (manual) Toe, Edge Page 11
Natural Protection Feature Line Most Landward Protective Feature 25 ft landward of Dune Heel or Bluff Edge 100 ft landward of Beach Edge Page 12
Historic Imagery Geo-referencing Challenges Over 500 images True ortho-rectification (image adjusted for topographic relief, lens distortion, and camera tilt) cost prohibitive for project ($$$ per image) Identification of control points in some areas of little or no development Two images taken on the same day 5/2/1979 Page 13
Structural Hazard Area Line 2nd Line on the Map Proxy Shoreline Water line ID based on 1979 imagery Datum Shoreline 1979 water level from gage extracted from 2011 USACE LiDAR Proxy Datum shoreline / 32 yrs SRR ft/yr SHA is plot where SRR is =/> 1ft/yr Page 14
2 Lines on a Map 13 points on 1 transect Page 15
How did we do? Sources of Error Calculation of the datum shoreline from Stockdon et al. (2002) method. 95% CI 3 ft average Geo-referencing of the 1979 imagery little to no error Location the proxy shoreline (water line hard to see, blurred imagery) +/-2.5 ft = 4 ft average Page 16
How did we do when compared to other studies? Town of Wilson Niagara County Baird (2006) 2.9 ft/yr for the Town of Wilson AECOM (2012) 2.6-3.9 ft/yr at inlet; 1.1 ft/yr to left and right of inlet Differences in method???? Page 17
How did we do when compared to other studies? Town of Ellisburg Jefferson County Baird (2006) 1.3ft/yr determined using dune toe position AECOM (2012) 1.5ft with a +/- 3% error at the 95% CI Page 18
Map Production Current Status Lake Eire Brant, Evans, Hanover and Hamburg Counties & Cattaraugus Reservation 869 transects 51 panels scale 1:2400 Lake Ontario Jefferson, Oswego, Cayuga, Wayne, Monroe, Orleans, Niagara counties Approx. 6300 transects 341 panels scale 1:2400 Page 19
What Comes Next Map Adoption Public Hearing Process Procedure outlined in NY Code Section 34-0104 Identification of Coastal Erosion Hazard Areas Property Owner Identification and Notification (Certified Mailing) Maps will be available on website for review Public Meeting / Public Hearing Minimum 60-day period for consideration of comments Final identification Page 20
Questions? http://www.dec.ny.gov
Thank You jeffrey.burm@aecom.com elena.drei-horgan@aecom.com