San Jose, California is feared by the absence and excess of water.
Until recently, the city had suffered from a prolonged period of drought which forced almost a million residents to reduce their water consumption. Like many coastal cities, San Jose is also vulnerable to rising sea level rise, which has exposed the city to chronic flooding.
In 2017, San Jose saw the worst flooding to reach the Silicon Valley in a century – a reservoir product flowing into the local Coyote Creek, capturing hundreds of residents in their homes and forcing more than 14,000 o other people to leave.
Read more: t A small town in California has sunk over 2 feet in the last decade, and could be part of an unpleasant trend.
The combination of drought and flooding has led to a process called salt water intrusion – what the Mayor of Sam Liccardo refers to as the city's greatest climate threat.
In times of drought, California farmers have gone over-pumping water through underground aquifers (bodies of porous rock acting as a natural filtration system). In coastal regions such as San Jose, overcrowding allows sea water to leak into the aquifers of the city, revealing excess sodium to local residents in their drinking water. The problem is exacerbated by sea level rise, pushing inland water around the land towards the city's filtration system.
Liccardo calls a combined threat of drought and flooding "one of the challenges of very severe climate change but with little attention." If salt water intrusion continues to occur, he said that eventually he could pollute millions of Californians freshwater supplies.
Although scientists are still studying the effects of excess sodium on drinking water, early research suggests that it could lead to hypertension and chronic kidney disease.
Liccardo said that no city, including its own city, has calculated how to eradicate the problem.
"The closest thing we have to answer is to pump a lot of fresh water back into the aquifers," he said. At the moment, San Jose is working on a plan to increase the amount of water that has been purified, recycled – essentially, sewage that was filtered, cleaned and disinfected – pumped in. to underground aquifers.
For now, water has been recycled mainly in irrigation, but the city hopes it can be mixed with groundwater eventually to offset the presence of salt water from The sea.
In 2014, San Jose revealed a $ 72 million purification factory that aimed to produce billions of gallons of water to recycle for the city. Liccardo hopes to expand this state-funded initiative, the local Santa Clara Water District, and returns on the city's investments in water recycling.
The city is also working with the local water area to invest in levy construction, but Liccardo said that these efforts will only protect structures from sea level rise, not saltwater intervention.
"What happens in the underground aquifers is far more challenging from an engineering perspective," he said.
Whatever the solution to salt water intervention, Liccardo knows that it will not be straightforward. So far, he said, "Nobody has calculated how to make their communities fully resilient to all known and unknown changes caused by a rapidly changing climate."