By Martin Zoffmann and Michael Rothenborg, November 2017
California currently produces more than 80% of the world’s almonds, and each little nut takes almost four litres of water to grow. All in all, the state uses more than four trillion litres annually for almond farming – that is one-fifth more than Californian families use at home.
The agro industry’s production and consumption methods are in other words not exactly sustainable - especially when you consider that longer and more permanent droughts are forecast in the future.
In dry years the groundwater part of the state’s total water supply increases from approximately 38% to 46% or more. Some communities rely entirely on groundwater for their drinking water, and it is a critical resource for many farmers in the Central Valley and Central Coast regions. California authorities are thus investigating ways of better mapping and utilising groundwater resources.
Ramboll has been engaged to help authorities reduce the risk of salty seawater’s infiltrating fresh groundwater in a large area near Monterey Bay (pictured).
“The so-called saltwater intrusion occurs when underground aquifers have been over-drafted, and the pressure gradient pushes seawater inland and underground,” says Max Halkjær, a Ramboll market manager and groundwater specialist.
Never had the technology
Ramboll is using its experience from mapping groundwater in places like Denmark to get a clearer picture of when and where to find the fresh groundwater before it gets intermixed with saltwater.
“Ramboll is collecting the data by using SkyTEM technology, which involves flying over an area with a helicopter carrying electromagnetic sensors that can scan the geological layers. Santa Cruz County Water Resources Planner Sierra Ryan describes this effort as a “key piece of the puzzle” in the ongoing work of charting the impact of water overuse in the area.”
“Nobody’s ever done this in California before. We’ve never had the technology,” Sierra Ryan told the local news site the Santa Cruz Sentinel. “It has to be able to penetrate through the ocean. What we’ve done similar to this is that we drill wells, but we’re not drilling monitoring wells offshore.”
In Monterey the investigations are carried out in collaboration with Soquel Creek Water District and Santa Cruz Mid-County Groundwater Agency.
Ramboll is also talking to several other potential clients in California about securing a more sustainable water supply.
Collaboration on water technology
In September this year Ramboll’s Max Halkjær was invited to California Governor Jerry Brown’s office to give an inspirational presentation on “Integrated Data Management for Regional Groundwater Planning”. Danish Minister for the Environment and Agriculture Esben Lunde Larsen was also present and signed a deal with
Governor Brown on water collaboration.
A range of companies and utilities in Denmark and the USA, including Ramboll, have formed the Water Technology Alliance (WTA) forum, whose main purpose is to share knowledge and develop new solutions to the water-related problems caused or worsened by climate change.