Panelists: Peter Slovinsky, Maine Geological Survey; J.T. Lockman, Southern Maine Regional Planning Commission; Ken Buechs, Biddeford Citizen Representative, Sea Level Adaptation Working Group
Sea level is rising. What are the impacts? How do communities respond? Science shows sea level is rising 1.9 mm/ year at the Portland tide gauge. The rise is trending on the upper end of the IPCC assessment. A stakeholder group formed in 2004 to rewrite coastal sand dune rules to adopt a two-foot increase in sea level. In addition, a coastal wetland was defined to include the highest annual tide level.
Saco Bay is the largest estuarine system in the area and is comprised of four communities: Scarborough, Old Orchard Beach, Saco, and Biddeford. Approximately five years ago, a coastal hazard resiliency tools project began, funded by the Maine Coastal Program with scientific data assistance provided by the Maine Geologic Survey. The project focused not on the causes of sea-level rise, but on adapting to real sea-level rise. The group developed a regional approach, with participation by towns and the Southern Maine Regional Planning Commission. The project showed that sea-level rise could be tied to a tax revenue loss and showed there should be changes to ordinances such as placing new buildings on piers.
Moving forward, a working group was formed that included two members from each community in addition to J.T. Lockman and Pete Slovinsky. It was funded by a regional challenge grant from the State Planning Office and local match. The group developed a vulnerability assessment that showed potential damage to buildings, wetlands, and roads and used a two-foot rise in sea level. They created a vocabulary for communities to understand. They stimulated potential impacts to natural resources by ground-truthing LIDAR data, determining tidal elevations, demonstrating accuracy in simulating existing conditions using tidal elevations to define marsh habitat inundation, and simulating sea-level rise. The caveat is that topography stays the same since current technology limits changes to this in the modeling process.
The group found that low-lying uplands were shown to be wet (high marsh) in the future. The tool can pinpoint areas that will be under water in the future and can pinpoint where the marsh will move. Saco Bay is currently dominated by high marsh and the tool shows a decrease in high marsh with an increase in low marsh.
The tool also shows what buildings will be impacted by sea-level rise. It can determine where the deepest flooding will be and associated costs. The tool also shows impacts to road infrastructure. For example, certain roads that are emergency access points may be flooded.
The project is expanding to York, Kennebunk, and Ogunquit. For example, Gerrish Island in Kittery could have freshwater ponds on the island converted to salt water after a two-foot rise in sea level. Also, the Portsmouth Naval Shipyard could experience significant flooding with a one-meter rise.
The Action Plan included regulatory changes to shoreland zoning, sand dune, NRPA, and Site laws. Local actions included amending local zoning and the floodplain management ordinance. In addition, the plan attempts to work with other groups to save money and be more efficient. The action plan proposes cuts in red tape by standardizing floodplain management, building code interpretations, zoning ordinance review, and allows non-binding comments during development review that affect Saco Bay from other towns.
Potential regional adaptation techniques include land purchase, emergency access re-routing, tidal flow control, removing tidal restrictions, increasing freeboard required by floodplain management standards, utility relocation and elevating vulnerable infrastructure, roads (example given from 10/25/2010 New York Times Article titled, “Front-Line City in VA Tackles Rise in Sea”), plan capital investment plans with sea-level rise in mind, improve shoreland zoning maps using LIDAR, adjust definition of shoreline to leave extra room for sea-level rise (for example, Ogunquit uses a position of four-feet higher than the current highest annual tide).
by Lisa Vickers