The Key to California’s Survival Is Hidden Underground

Water is Nemesis of urban planners. Because the built environment is so impervious to liquid, thanks to all that asphalt, concrete, and brick, it builds up instead of seeping into the ground. That’s how you get severe flood it’s been haunting California for weeks, so far killing 19 people and possibly calling $30 billion loss.

Traditionally, engineers have treated storm water as a nuisance, building complex infrastructure such as gutters and canals to direct the flow into rivers or oceans before it has time to form a puddle. But in California and elsewhere, climate change is forcing that strategy to change. As the world warms, more water evaporates from the earth into the atmosphere, which itself can hold more water as it gets hotter. Storms in the Golden State will be less frequent, but more water will be released faster. Stormwater systems simply cannot drain water fast enough.

To prepare for this damp future, engineers are turning to a more natural flood control plan, forcing water to seep underground into natural aquifers. Such a plan would both mitigate the effects of the floods and help the American West store more water despite the unstable climate. “We need to think a little more creatively: how do we make the most efficient use of basically these huge underground sponges that we can use to supply drinking water?” says Katherine Kao Cushing, who studies sustainable water management at San Jose State University.

The California water supply system is designed for a mild Mediterranean climate. Rainfall in the fall and winter fills a system of reservoirs that feed the state during dry summers. But this system strains during a drought, like the one that is now devastating the state: the last three years have been driest three-year period since 1896. (Actually, drought can exacerbate flooding because dry land also doesn’t absorb water.) Before this series of storms hit, some California dried up. Now a reservoir across the state approaching the historical average. That’s how epic the rain was.

Snow cover is also important. It grows at high altitudes during the winter, then melts and feeds water bodies as temperatures rise. But climate models predict that much of the state’s snow cover will be gone by 2100, says Andrew Fisher, director of the University of California, Santa Cruz. Reload Initiativewhich studies groundwater resources. “Some models say it all,” Fischer adds. “Let it soak in for a second. That’s more water than all the dams in the state. It’s very sobering because there’s no way we’re going to double the number of dams.”

To wet your people and farming, California stepping up water conservation effortsfor example, install more low-flow toilets in homes and pay people to uproot their lawnswho are stupid for reasons other than thirst. It is the recycling of wastewater from homes and businesses into ultra-pure water that can be drunk. But most of all, he tries to retain sporadic rainwater, instead of draining it, to build the infrastructure to create “sponge cities”. They appear all over the world; the concept was widespread in Chinaand urban planners in places like Berlin in Germany and Auckland in New Zealand they use it to cope with heavier rains.