Drought, combined with increased pumping of underground water sources, is causing widespread land sinking in some parts of California, the US Geological Survey reported last week.
The report found that some areas in the San Joaquin Valley are sinking about a foot per year, faster than previously thought. The phenomenon is reducing the flow of two water sources, the Delta-Mendota Canal and the California Aqueduct. Ironically, those projects were constructed to provide more water within California, and pumping from underground aquifers lessened after they were built. However, the recent drought—which not only reduced rainfall but also caused the state to limit surface water use—has resulted in increased pumping of groundwater. The state does not limit the amount of groundwater that may be pumped.
Both the aqueduct and canal are managed by the US Bureau of Reclamation, which says it will take the USGS report into account for future construction. Other projects that could potentially be affected by the sinkage include pipelines and rail lines, such as the state’s bullet train project. As the article above notes, the California High Speed Rail Authority has already responded to the USGS report, saying that the rail system will be flexible enough to accommodate sinkage and ground movement.