Wednesday, July 10, 2013

Maryland's sea-level rise toll may be worse than predicted

Karl B. Hille and Sydney Paul in the Star Democrat via Capital News Service (Maryland): Gov. Martin O'Malley warned in December that rising sea levels over the next century would threaten "400 miles of roadways," when he signed an executive order making protection of billions of dollars in state infrastructure a top priority. However, a CNS analysis shows the total impact, factoring in county-maintained roads, could be much worse.

Maryland is home to more than 5,200 miles of state roads and about 21,000 miles of county roads, according to Maryland State Highway Administration documents. A CNS analysis found that roughly 800 miles of roads would be affected if sea levels rise another 2 feet. At 5 feet, an estimated 3,700 miles would be under water.

The bay already has risen more than a foot in the last century, and scientists predict it will rise 2 to 5 feet before the end of the next century.

The CNS analysis used land elevation data from U.S. Geological Survey and population survey data from the census. The effect of local man-made structures such as seawalls is difficult to determine and not included in the calculations.

The rising waters are expected to flood roads and weaken the foundations of bridges, causing some bridge decks to fail, according to state reports. A 2-foot rise in water levels would have an impact on 93 bridges, culverts and other highway structures.

Elizabeth Habic, manager of the climate change program at the State Highway Administration, said the agency has embarked on an ambitious mapping effort to identify which state roads are vulnerable to rising sea levels, so they can decide how to tackle the problem. "We don't know how to fix it yet," she said. "We're evaluating solutions."...

A 1911 panoramic view from the Maryland State House in Annapolis

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