Farmers in California's Central Valley are considering an extreme measure to help combat declining groundwater levels, and it may seem counterintuitive – they want to flood their own farms.
The land has become completely parched with drought, and Don Cameron, a farmer in the area who grows everything from almonds to grapes and tomatoes, suggests that stormwater is the answer.(1)
Cameron and the neighboring farming community are proposing to flood fields with storm runoff in order to allow the water time to seep into the massive aquifer that is located underground.
How do aquifers work?
Aquifers occur underground when layers of rock become saturated with water that can then be brought to the surface either naturally or using pumps.(2) Aquifers are one of the most crucial water sources on the planet – with about 30 percent of liquid freshwater held as groundwater at any one time.
The most productive aquifers are located in porous, permeable rock such as sandstone or limestone, where groundwater flows more easily, allowing for faster and easier extraction. A dense, impermeable layer, such as clay, lies directly underneath, holding the water in place until either the groundwater is extracted or the water table rises above the surface.
The water in an aquifer can be stored for hundreds of years, with many hydrologists estimating that some aquifers have been holding water for more than 10,000 years.
The current situation in California
The aquifer in California's Central Valley accounts for about 60% of the state's water supply – but its use is not currently regulated, and landowners can extract as much water as they wish.(3)
However, California is sinking – and at an alarming rate of more than 18 inches per year. This is thought to be due to the space left underground by the extraction of groundwater. The aquifer may be drying up.
In fact, California has permanently lost around 6 trillion gallons of water over the last century. According to the U.S. Geological Survey, if everyone in the state stopped pumping groundwater immediately, it would take 50 years for the aquifer to refill. But without a government agency closely monitoring the levels, this would be incredibly hard to achieve.
Replenishing groundwater in aquifers
This is where Cameron and other local farmers come in. The idea is simple – flood fields with storm runoff from El Nino during times when water isn't needed and allow it to replenish the aquifer. Cameron first came up with the idea in 1983, when a huge storm saw entire vineyards submerged – and yet they survived.
In 2011, Cameron started to put his theory to the test. He diverted stormwater passing by his property to flood a 300-acre vineyard for five months – and the experiment worked. Most of the water sitting on the land naturally drained into the aquifer, and the vines survived.
Cameron is now investing $7 million from a federal grant for the prevention of flooding to quadruple the capacity of the stormwater channel, hoping that El Nino will bring even more water this year. Other farmers are also joining him – with the general opinion that something must be done to replenish the aquifer resounding throughout the local community.
It is hoped that Sustainable Conservation, a Californian non-profit organization, will help Cameron spearhead this large-scale flooding experiment, the results of which could play a huge role in the long-term management and maintenance of the aquifer's groundwater – replenishing it for the future.