The intensive withdrawal of groundwater is causing land to sink in the lower Chesapeake Bay region, worsening the effects of sea-level rise and increasing the severity of floods along the Delmarva Peninsula and Virginia Coastal Plain.
Image courtesy PhotoSeoul/Flickr
Land subsidence, or the sinking of the land’s surface, is in part a natural phenomenon, occurring as bedrock responds to the melting of an ice sheet that once covered Canada and the northern United States. But according to a new report from the U.S. Geological Survey (USGS), most of the land subsidence in this area is taking place in response to groundwater withdrawal, which could help explain why the region has the highest rates of relative sea-level rise on the Atlantic Coast.
When groundwater is pumped out of the earth, water levels in the area’s underground aquifers decrease. As these water levels decrease, the aquifer system compacts, causing the land above it to sink. In the southern Bay region, land subsidence has been measured at rates of 1.1 to 4.8 millimeters per year—close to the width of five stacked pennies.
Land subsidence can increase flooding, alter wetland and coastal ecosystems, and damage human infrastructure and historical sites. Some areas in Virginia—like the city of Franklin and the counties of Isle of Wight and Southhampton—have already experienced floods as the land around them sinks, and the low-lying Hampton Roads could experience similar episodes soon.
But according to the USGS, a change in water use—from moving groundwater pumping out of high-risk areas to slowing rates of groundwater withdrawal—could slow or mitigate land subsidence and relative sea-level rise.
Gulls call to each other, belted kingfishers swoop down into the seagrass, monarchs chase the wind, and Alicia and I snap photographs of as much of it as we can. Fisherman Island is only open to the public during this time of year, and it is very likely that this trip will be our only opportunity to visit the tiny island at the southernmost tip of the Delmarva Peninsula.
Although thousands of motorists pass over the 1,850-acre land mass each day as they drive across the Chesapeake Bay Bridge-Tunnel, few of them know that this area is one of only 17 sites classified as a “wetland of international importance.” Thousands of migratory birds stop here each fall and spring, and monarchs feed on native plants as they make their winter trip to Latin America.
The refuge is closed to the public because many of these species, such as brown pelicans and royal terns, are sensitive to threats from humans.
The Eastern Shore of Virginia National Wildlife Refuge, part of the U.S. Fish and Wildlife Service, manages Fisherman Island. Refuge law enforcement makes sure that the public – and yes, even fishermen – stay away.
Alicia and I were afforded access to Fisherman Island through Chesapeake Experience, a non-profit organization that offers summer camps, eco paddles, corporate retreats and experience-based environmental education for educators and students. Chesapeake Experience Director Jill Bieri and two refuge staff members led a morning walk on the island’s nearly unspoiled beach and an afternoon kayak tour from the Chesapeake to the Atlantic.
But this trip is a different kind of Chesapeake experience for us, coming from Annapolis, where the Bay’s brackish water forms a distinctive landscape.
Most of the tour participants are avid birders and have come prepared with binoculars. We see many yellow-rumped warblers, or “butter rumps,” (Dendroica coronate) squeaking back and forth across the path.
There are plenty of other interesting features to observe at Fisherman Island, including:
Although we find treasures that we’re not likely to see in Annapolis, we also saw something disappointing: plastic bags that have washed up on shore and are now buried deeply in the sand.
To me, this illustrates why efforts to restore the Bay need to collaborative, involving agencies like the Fish and Wildlife Service, non-profits like Chesapeake Experience, and regular people like you and me. Although this tract of land is hardly touched by the public, and managed meticulously by the government, it is still vulnerable to the pollution that is happening throughout the Bay.
That afternoon, we paddle to where the Chesapeake Bay pours into the Atlantic Ocean, following the meandering path of the water through the marsh. Sitting on my kayak in this water, I feel it drift in and out of the Bay, and realize that the boundary lines between ocean and bay are fuzzy, or even, invisible.
A great blue heron watches us kayak into the waves. Our group slowly paddles to him, waiting for his five-foot wing span to cast a shadow over us. His flight makes our cameras snap and mouths hang open.
Jill instructs us to turn back before the waves get too rough. After all, we’re only novice kayakers!
Our homeward bound drive along Route 13 reveals abandoned homes alongside tents selling Virginia pecans, fireworks and cigarettes, all of them advertising their products with home-made, home-painted signs dotting the side of the road.
Mobile homes, their porches decorated with pots and pans and people in rocking chairs, sit on large tracts of land that I imagine to once have been profitable tobacco or cotton farms.
As the sun sets, these surroundings disappear, and we have only the stars to look at until we reach Annapolis.