LAND SUBSIDENCE INDUCED BY GROUNDWATER PUMPING AS A CONTRIBUTOR TO HIGH RATES OF RELATIVE SEA-LEVEL RISE IN THE VIRGINIA COASTAL PLAIN

Land subsidence induced by groundwater pumping is most likely a reason for the southern Chesapeake Bay region having the highest rates of sea-level rise on the U.S. Atlantic coast. The relative sea-level rise that the southern Chesapeake Bay region of the Virginia Coastal Plain is experiencing is the result of both land subsidence and global sea-level rise. Land subsidence has been observed since the 1940s in the Virginia Coastal Plain at rates of 1.1 to 4.8 mm/yr. Land subsidence increases the risk of flooding in low-lying areas, which has important economic and human health consequences for the heavily populated and ecologically important southern Chesapeake Bay area. Aquifer system compaction caused by extensive groundwater pumping in the Virginia Coastal Plain accounts for more than half of the land subsidence and has occurred at rates of 1.5 to 3.7 mm/yr throughout the region. Glacial isostatic adjustment, or the flexing of the earth’s crust in response to glacial loading and unloading during the last glacial period, also likely contributes to land subsidence in the region.