That can’t happen overnight, or even, experts expect, terribly quickly — it might take thousands of years. The US Army Corps of Engineers suggests planners expect five feet of sea-level rise by 2100. That’s also the upper end of most official state and local estimates, which are usually based on the readings from the official tide gauge on the Maine State Pier. It’s enough to put Portland’s waterfront roughly back at Fore Street, which is where it was before Commercial Street was built on fill in the middle of the
Faced with that level of change, what should we do? Is a seawall the right answer? How big should it be, and where? What about building a new school, or moving a sewage-treatment plant? The dollar amounts for these things are always in the millions, if not the billions. Nobody wants to spend that much money and find out years from now it was too much — or too little, or the right amount but in the wrong place.
“We don’t need more data. We need more conversations,” Merrill says. (See sidebar, “Reports, And More Reports,” for a sampling of some of the data that’s been out there for years.)
Setting up the conversation
It’s important to have something concrete to talk about, though. That’s where Merrill’s method comes in. It is built on mathematical formulas developed by Paul Kirshen, a civil-engineering professor at the University of New Hampshire, coupled with three-dimensional imagery and modeling assembled by Hallowell-based Blue Marble Geographics.
The software is free to download and use, though it requires a certain level of familiarity with Geographic Information Systems data management, as well as access to property records and elevation data in certain specific formats. While hard to assemble on your own at home, it’s well within the range of most municipal planning-department staffers.
Relatively new data with extremely fine detail about elevations is key, says Blue Marble president Patrick Cunningham: “Five centimeters is the difference between (safety and) flooding the town.”
People can quickly identify the places where risk is highest (notice how fast you processed the information in the accompanying map of the Portland peninsula, below), and where it’s low or absent.
This clears people’s fear of the unknown, Merrill says, and turns it into civic engagement to address what are now clearly identifiable problems.
People can see what will happen if no action is taken in the face of sea-level rise and storm surge, as well as what will happen if certain specific actions are taken, allowing city leaders and average residents to compare a set of options for the future. Is a seawall better in one place, or should one area be allowed to flood to save another area that’s more important for some reason?
Merrill says it’s “really putting people in the driver’s seat and helping them evaluate their own risk tolerance.”
What he brings is not only the expertise to construct a strong set of models of various conditions, but also experience facilitating the conversations that must necessarily follow.
He finds, often, that people “are fed up with all the planning and never getting to implementation.” But the decision to pull the trigger is difficult.