Wednesday, October 22, 2014

Tidal Floods and Durham’s Temporal Resume

I live in what geologists call a “rift basin.”  Along the eastern edge of Durham, North Carolina marks where the continents of North America and Africa broke apart creating a widening gap filled with the Atlantic Ocean hundreds of millions of years ago.

On the other side of the jointly-owned airport, Raleigh lies down in a “falls zone” marking a bay of the vast coastal plain that forms nearly a half of North Carolina, essentially an ancient, receded tidal flood plain.

Early explorers such as John Lawson would have probably recognized this “falls zone” as where rivers began to cascade down water falls created by a fault line where he passed over what is now northeastern Durham, before they slowed and widened out on their way to the ocean.

So named is Falls Lake created in Durham in 1981 from three rivers flowing down from an ancient volcanic arc around northern Durham.  It was impounded as a means to fuel the growth of Raleigh and Wake County, which at one end of that violent arc notoriously had trouble percolating water.

There is a fascinating, easy to read book co-written in 2007 by a science writer here Durham along with a geologist down at UNC-Chapel Hill, entitled Exploring the Geology of the Carolinas.

It includes a map of physiography showing that the coastal plain doesn’t underlie Raleigh from the east but pushes up into that community from Fayetteville and the Sand Hills to the south as a sort of bay.

My interest is not coincidental.  It is highly recommended that anyone inventorying the sense of a particular place, as I did for Durham, begin with its geologic formation where distinctiveness first takes root.

I josh about Durham having once been a “beach town” but it was at least along a sound or an Intracoastal Waterway, and might be again some day.  Its elevation is measured at 404 feet above sea level.  But parts are much higher and where I live slightly lower.

It has been worn down by erosion over time and its underlying rift filled with softer Triassic sediment makes it vulnerable to legislators prematurely pushing natural gas extraction, known as “fracking,” even before questions about the technology’s threat to water quality are resolved.

This is how “representative” democracy turns despotic because Durhamites have virtually no say or way to vote their conscience against those wreaking this unique havoc on only a few very narrow slices of North Carolina.

It turns out those defiant about “states’ rights” are worse than any federalist in their refusal of “locals’ rights.”

There are many reasons to visit the 84+ acre Museum of Life and Science in Durham but one is Explore the Wild, an exhibit wonderfully retro-purposed back to wetlands and habitat for wildlife from an old quarry.

Dormant since 1939, the quarry dated back to the early 1900s when  motor vehicles emerged making creation of roads a higher priority.

As the quarry deepen nearly a hundred years ago, it exposed part of Durham’s geology unique to much of North Carolina including nearby settlements.

This is just one of several quarries here now reclaimed by nature including one as a 4-acre lake with a 60’ cliff tempting to divers and another as an emergency city reservoir.

At one time the mountains of western North Carolina were as high as those around Mt. Everest, meaning the width of the base would slope to what is now Durham adding “mountain town” to its sense of place resume at one time.

We’re “playing with fire” ‘er…better make that floods…when it comes to mitigating our human effect on global warming dating to the mid-1700s with the dawn of the Industrial Revolution.

But in the history of the earth where I live, sea levels at one time spiked 20 feet higher than today and scientists have evidence there was a time it spiked 800 feet higher here, making Winston-Salem a beach town and all of the state’s other major cities mere novelties for deep sea divers.

Globally, sea levels have risen eight inches since 1880 according to analysis of records in a new scientific report entitled Encroaching Tides.

People who live along the coast see this in the increased days of tidal flooding, which in some communities has quadrupled in frequency over just the past forty years.  Or maybe they are like the frog that fails to detect when water is slowly brought to boiling.

It isn’t just the nuisance that flood events represent now.  Tidal events rise exponentially to overall sea levels and already they are disrupting commerce and related tax revenues, often stretching through entire neighborhoods.

But the report calibrates that these regular flood events are also due to reach far farther into communities all along the Atlantic coast.  If confused by claims of projections being partisan, just ask those in the business of insuring risk.

The report breaks down what the increase means to specific coastal communities by comparing tidal flooding today with what it will become in 15 year increments out to 2045.

Here in North Carolina, the report looks at the communities of Duck, Wrightsville Beach and Wilmington, the state’s eighth largest city and a port.

Duck along the very northeast corner of our coastline will increase from 8 annual flooding events currently to 32 by 2030 and to 126 by 2045.  Farther south, tony Wrightsville Beach will increase from 8 currently to 29 by 2030 and 90 by 2045.

Flood events in Wilmington will increase from 44 a year now to 133 by 2030 and 343 by 2045, with each one penetrating farther and farther inland, which means such communities need to take the actions recommended in the report seriously.

Scenarios beyond 2045 predict that these flood events will continue to increase.  If I am lucky enough to live as long as my mother has, I will see portions of coastal communities abandoned and not just in New Jersey where the coastal plain is 1/10th as wide.

For coastal towns, my jest about Durham being able to one day add “beach town” back to its sense of place resume is no laughing matter, nor is developer-driven stalling in the legislature.

But all the same, I think I’ll continue to put off any inkling to ever rent or buy a beach house and stick with my preference for mountain lake cabins.

No comments: