Wild Side : Nature is the best defense
As you drive from the drawbridge toward Five Corners, the first metal Martha's Vineyard Shipyard building you come to greets you with a dark line and the words "High water 1954" at roughly eye level. Imagine the peninsula you're driving along submerged in seawater to that depth.
Even routine storms, the kind we get a dozen of each year, blow down trees, flood or undermine roads, drop wires, and chop away chunks of shoreline. The good news is that Islanders have always rebounded from the impacts of major storms and taken prudent measures to minimize damage. The bad news is that, because of the accelerating climate change human activity is triggering, we're going to have get better at it.
Estimates vary somewhat and depend strongly on whether or how fast greenhouse gas emissions continue to increase. But over the next century, the sea level appears likely to rise about three feet, putting existing roads and structures closer to - or under - the waves. Moreover, storms may grow more frequent in the future, and the force of the strongest storms that hit us is likely to increase. In combination, elevated sea levels and magnified storms will speed erosion, produce higher surges, and intensify flooding along the Island's shoreline.
Human responses to these challenges will surely involve a range of measures. Some vital roads and structures can be fortified by new or expanded sea walls. But shoreline hardening has critical limitations. It's expensive, for one thing. It can be undermined by severe storms. And because it interferes with the production and movement of sediment along the shoreline, protecting one point usually means increasing erosion someplace else. Shoreline hardening doesn't solve a problem; it just moves it.
In response to this quandary, civil engineers and public planners are increasingly taking a new tack on shoreline protection: relocating what we can, hardening what we must, but generally relying on the natural dynamics of shorelines to protect us. Marshes and beach-dune systems are certainly subject to damage by storms. But by their very nature, they recover, and in the process of sustaining damage, they absorb energy from waves or storm surge, protecting the uplands behind them.
The Massachusetts Coastal Zone Management office has developed a program called StormSmart Coasts (www.mass.gov/czm/stormsmart) to assist local governments in turning this philosophy into practical measures. StormSmart principles include discouraging new development in areas vulnerable to flooding; requiring storm-resistant construction in flood zones; encouraging the relocation of infrastructure that is or will be at risk; and restoring natural shoreline systems to buffer uplands from storm effects.
My own town of Oak Bluffs has enlisted as one of eight "pilot communities" in the StormSmart program and has already begun implementing this philosophy in planning and engineering projects, according to Liz Durkee, the town's conservation agent. For example, a revegetation project on the bluff overlooking the public beach employs the natural resilience of beach plants to stabilize the vulnerable slope and protect the road above.
Another proposed StormSmart measure is a zoning bylaw revision on the warrant for the upcoming O.B. town meeting, which begins April 13. While the wording of the proposed bylaw is complex, its essence is simple: based on the best available maps showing local susceptibility to flooding, specific coastal portions of the town would see increased regulation of construction, renovation, or major repair of existing buildings. In small areas at the greatest risk, new development would be prohibited; in less risky areas, specific kinds of construction would require a special permit from the town, with the stringency of permitting requirements corresponding to the level of risk. The need for special permits would allow the town to insist on construction methods that reduce the chance of damage.
The proposed bylaw would impose limitations on land owners in flood zones, but it's important to remember that, through insurance and emergency aid programs, society at large subsidizes the risks faced by waterfront property. Town personnel may be placed in danger rescuing people and property threatened by a flood, and towns and abutters experience the impact from floating debris and washed-out septic systems. From that perspective, and given the probability that flooding will grow worse in the future, it's not unreasonable to give municipalities a stronger say in where and how waterfront construction takes place.
A public Planning Board hearing on the floodplain bylaw takes place tonight at 7:00 at the Oak Bluffs town hall. Whether the proposed bylaw correctly balances property rights and community interests is for town meeting, and ultimately the future, to determine. But from here on the Wild Side, an orderly retreat from existing shorelines and increased reliance on natural systems for flood defense look like wise approaches to a problematic future. And the proposed Oak Bluffs bylaw revision, while a pioneering and hence perhaps imperfect response, represents a thoughtful and forward-looking step for a coastal town to take.