While much of what we post on Waterless World revolves around the many water scarcity issues that are growing globally, the broad mandate is to address global water-related issues. This recent report from Reuters Investigates focuses on the local challenges to communities as the incidences of coastal flooding continue to grow. The report, Water’s Edge, is appearing in two parts. Part 1 focuses on their analysis that finds that flooding is increasing along much of the nation’s coastline, forcing many communities into costly, controversial struggles with a relentless foe.
Since 2001, water has reached flood levels an average of 20 days or more a year in Annapolis, Maryland; Wilmington, North Carolina; Washington, D.C.; Atlantic City, New Jersey; Sandy Hook, New Jersey; and Charleston, South Carolina. Before 1971, none of these locations averaged more than five days a year. Annapolis had the highest average number of days a year above flood threshold since 2001, at 34. On the Delmarva Peninsula, the annual average tripled to 18 days at the Lewes, Delaware, tide gauge.
The flood threshold does not measure actual flooding. It indicates the level at which the first signs of flooding are likely to appear – ponding on pavements and such. The higher the reading, the higher the probability of closed roads, damaged property and overwhelmed drainage systems. Scientists consider the readings to be a reliable indicator of actual flooding.
The Reuters analysis shows that the “impacts of climate change-related sea level rise are increasing frequencies of minor coastal flooding,” said William Sweet, an oceanographer for NOAA who led a team of scientists that released similar findings in late July. The NOAA study examined 45 gauges and found that flooding is increasing in frequency along much of the U.S. coastline and that the rate of increase is accelerating at sites along the Gulf and Atlantic coasts.
The coastal flooding is often minor. Its cumulative consequences are not. As flooding increases in both height and frequency, it exacts a toll in closed businesses, repeated repairs, and investment in protection. In effect, higher seas make the same level of storm and even the same high tides more damaging than they used to be.
In Charleston, a six-lane highway floods when high tides prevent storm water from draining into the Atlantic, making it difficult for half the town’s 120,000 residents to get to three hospitals and police headquarters. The city has more than $200 million in flood-control projects under way.
In Annapolis, home to the U.S. Naval Academy, half a foot of water flooded the colonial district, a National Historic Landmark, at high tide on Chesapeake Bay during rainstorms on April 30, May 1, May 16 and Aug. 12. Shopkeepers blocked doorways with wood boards and trash cans; people slipped off shoes to wade to work in bare feet.
Tropical storm flooding has worsened, too, because the water starts rising from a higher platform, a recent study found.