More Frequent Flooding a Serious Concern

By LIZ DURKEE

One day last month close to five inches of rain fell on Martha's Vineyard. In Chilmark alone it caused a five-foot wide, four-foot deep sinkhole on State Road, the collapse of a two culverts and the dirt road to Lucy Vincent Beach, the collapse of an old granite bridge and the closure of South Road near the Allen Farm due to an impassable puddle.

Suddenly it's flooding everywhere, all over the world - and it's no fluke.

It's raining harder and more frequently as the planet and ocean waters warm due to human-induced greenhouse gas emissions. Flooding is intimately connected to other climate change impacts: sea level rise, land erosion, more frequent and intense storms, and a rise in storm surge.

The official FEMA flood maps for the Island are at least 20 years old; today the floodplain is much larger than the maps suggest. The so-called 100-year storm, a storm with a one per cent chance of happening in any given year, is now expected to happen every two to 10 years.

Flooding is not a natural disaster. It is a natural event that becomes a disaster for people and other obstacles in its natural path - the floodplain. On the Vineyard land in the floodplain - beaches, banks, dunes, salt marshes and low-lying developed areas near the shore, ponds, and streams - is among the most expensive of all properties. As flooding becomes worse these properties will be at greater risk of flood damage, not to mention the Island's man-made infrastructure - the roads, bridges, public buildings and utilities in harm's way.

The Island is awash with antiquated drainage systems. Decades of development have created more paved, impervious surfaces and led to the loss of trees and vegetation that would otherwise help absorb and filter flood waters.

According to the U.S. Environmental Protection Agency in a report on climate change indicators, "Climate change can affect the intensity and frequency of precipitation. Warmer oceans increase the amount of water that evaporates into the air, and warmer air can hold more moisture than cooler air. When this moisture-laden air moves over land, it can produce more intense precipitation -for example, heavier rain and snowstorms. The potential impacts of heavy precipitation include crop damage, soil erosion, and an increase in flood risk due to heavy rains. In addition, runoff from precipitation can hurt water quality as pollutants deposited on land wash into water bodies."

Increased flooding will inundate roads, basements, homes and businesses with water. Towns will need to update drainage systems and it is no longer legal to let untreated stormwater flow into water bodies. Coastal roads will flood, traffic will increase on inland routes. It will become more expensive for towns to pump floodwater, repair roads, and cleanup after floods. Some roads and homes will have to be elevated or abandoned. Lives and jobs will be disrupted; the local economy will suffer.

Heavier rain means pollutants will be swept faster into already stressed coastal ponds, causing increased swimming and shellfishing closures. Intense rain and flooding will increase algae blooms. Saltmarshes will be overwhelmed, affecting their ability to retain and filter floodwater.

Increased flooding means more human health problems. Standing water is the mosquito's best friend; it increases the size of their breeding grounds and the likelihood of more vector-borne diseases such as West Nile virus. Flooding causes physical injuries and disrupts emergency medical response due to flooded roads.

Disease caused by flooding will become a threat here as the temperature rises. In their book, Changing Planet, Changing Health, authors Dr. Paul R. Epstein and Dan Ferber note: "In Honduras, two months after Hurricane Mitch, health officials saw spikes in diarrhea, respiratory infections, rodent and water-borne leptospirosis, and dengue fever."

The authors add: "The most widespread health risks from flooding arise as the waters ebb ... mold grows quickly on damp surfaces, especially when it's warm and dank, and it can cause serious respiratory illness."

Intense rainfall and flooding will also affect agriculture - plant and vegetable crops due to soil erosion, saturation and increased fungal growth.

How does the Island community plan for increased flooding and related climate change impacts? It is a new world; historical data is no longer an accurate guide.

Stephen McKenna, Cape and Islands coordinator of the Massachusetts Office of Coastal Zone Management, is not optimistic that the FEMA flood maps will be updated anytime soon. "It's up to the towns to figure out the local flood zones," he said with a sigh.

But Mr. McKenna and CZM have a wealth oftechnical assistance to offer the Island. He is spearheading round two of CZM's Cape and Islands StormS mart Coasts Program. Last year, Oak Bluffs was one of several Massachusetts towns chosen for the Storm-Smart Coasts pilot program. As a result, the town updated its floodplain zoning bylaw to insure that any development in the floodplain will have no adverse impact on surrounding properties. It would make perfect sense for the Island to apply for round two of the StormSmart Coasts Program as a whole - to propose developing an Islandwide shoreline vulnerability assessment. It is also possible for the Island to partner with FEMA, to use our local expertise to help them update the flood maps and pressure them to make Island mapping a priority.

But everyone of us can help. Local plants survive here for a reason; they tolerate salt and spray and water, they filter pollutants, help stabilize soils and prevent erosion. Lawns do not. Chemically maintained lawns and paved driveways add pollutants to the system. And the root systems of trees not only absorb water and pollutants but help absorb greenhouse gas-induced carbon dioxide.

Flooding is just one example of how climate change is affecting the Island – the natural environment, human health and the economy. It's all intertwined. And there is no escape, no magic cure. It's time to start planning to adapt to the changes. This Island community, if we unite, has the will, expertise, and incentive to make smart climate change decisions now. It's time to jump start the process.

This series of 14 essays about climate change was published in the Vineyard Gazette over a period of seven months in 2011. It appears here with permission. Copyright Vineyard Gazette. All rights reserved.
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