A NASA report pinpoints the threat that the Central Valley of California is facing in terms of ground subsidence due to massive volumes of groundwater being pumped in this period.
Drought-ridden California has been pumping groundwater from the state’s aquifers at an increased rate to counter the effects of the severe drought it is facing. While it is a necessary measure as California is well into the fourth year of drought, the process comes at a cost.
Pumping groundwater from the aquifers is leading the ground to sink and collapse. Some regions of the state are sinking as much as two inches monthly. Infrastructure has to suffer, with bridges, aqueducts and roads being at a high risk of damage.
It is of course not novel that land is sinking. However, the rate at which this is happening now is not good news for Californian authorities. The NASA report is based on satellite imagery collected during a two-year timeframe, from 2013 to 2015.
Subsidence is most noticeable in Central Valley, with some regions such as the one along the California Aqueduct sinking by 3 to 7 inches. The California Aqueduct spreads on hundreds of miles and is key for communities existence and farming.
The region to the east of Avenal has sunk by over a foot, while around Sacramento the ground is subsiding between 1 and 3 inches. The area surrounding Corcoran subsided by 13 inches over the past eight months.
Groundwater levels are also decreasing at an alarming pace. From the last measurement, groundwater levels have dropped by as much as 100 feet, according to Mark Cowin, who is the head of the California Department of Water Resources.
“We are pumping at historic levels”,
In order to address the issue, in 2014 Governor Jerry Brown signed legislation that asks counties to monitor the levels of groundwater in the aquifers and usage. Nonetheless, with counties having a deadline until 2020 or beyond to draft groundwater management plans, the measures will take more years to come into force.
Yet, the matter is of utmost urgency. To lend a helping hand, the Department of Water Resources has already signed 10 million dollars to invest in county conservation plans and groundwater management programs on the short-term.
The NASA report is intended as a tool for better understanding the frame and the consequences of pumping groundwater on ground subsidence. San Joaquin Valley well casings have already suffered extensive damage due to ground sinking. In time, the report warns, the aquifers’ capacity to store water may be diminished.
Immediate action is needed if extensive investments in infrastructure are to be avoided and communities saved.
Photo Credits: newsservice.org