Charleston Is Sinking Into The Ocean Far Faster Than Previously Thought


According to new data from a collaboration of local universities and state agencies, Charleston is sinking faster than previously thought. Several parts of Beaufort, Colleton, and Charleston counties have sunk over 2 inches since 2007, and some areas on St. Helena Island have sunk more than 3 inches.

Subsidence, or sinking land, worsens flooding, damages infrastructure, and causes buildings and bridges to crack.

Researchers at the South Carolina Office of Resilience are ramping up efforts to better understand and slow the subsidence. Excessive groundwater pumping can accelerate land sinking. Long-term aquifer water withdrawal drops water levels, causing land to sink. Removing oil and gas also contributes.

If groundwater pumping causes subsidence, South Carolina might need to change water sources or pumping schedules. Groundwater extraction is a known cause of subsidence in California, Texas, and Arizona. However, it is less of an issue in South Carolina, with about 40 active coastal wells showing minimal water level declines.

Heavy infrastructure like high-rise buildings and highways can also cause land to sink. Limiting heavy construction might slow subsidence, but it is impractical. Natural factors, such as the earth’s response to retreating ice sheets, could also play a role.

South Carolina’s Office of Resilience is now seeking funding for extensometers to monitor subsidence. These costly instruments would reveal if land is sinking at the surface or within deeper aquifers.