Reversal Possible in Cities Sinking Due to Groundwater Depletion
Research shows that sinking coastal and major cities can rise again by restoring groundwater levels, with tectonic fault lines playing a critical role in this process.
While many major cities around the world face the threat of sinking each year due to the excessive extraction of groundwater resources, new research reveals that this process can be reversed. Groundwater replenishment and the location of tectonic fault lines directly affect the rate of ground uplift.
Ground Subsidence Problem Worldwide
Due to the excessive extraction of groundwater reserves beneath them, many cities around the world are slowly sinking, leaving coastal cities vulnerable to rising sea levels.
While Indonesia's Jakarta sinks by more than 10 centimeters per year, it is projected that 15 percent of the population in China's Tianjin could be submerged if current trends continue.
Mechanics of Water Withdrawal and Solutions
When groundwater is pumped out, the underground aquifer acts like a deflating balloon, causing the soil above it to collapse.
Improved groundwater management can slow or completely halt this process; following strict regulations introduced in the 1960s in Osaka, Japan, ground conditions were monitored using satellites and wells.
Ground Uplift Observed in Osaka
Results obtained for the whole of Osaka revealed that with the recovery of groundwater levels, the ground rose by an average of 4 millimeters per year, and up to 12 millimeters in some areas.
This uplift formed narrow corridors aligned with tectonic fault lines that blocked groundwater flow, allowing water and ground uplift to increase faster on the upstream side.