California has seen so much rain in recent weeks that fields have been flooded and normally dry creeks and drainage ditches have turned into torrents of water flowing toward the ocean. Still, most of the state remains in severe drought.
All that runoff during a drought begs the question: why can’t more rainwater be collected and stored for the long, dry spring and summer when needed?
As a hydrogeologist at the University of California Santa Cruz, I’m interested in what can be done on a large scale to accommodate runoff from these types of storms. There are two primary sources of large-scale water storage that could help put a dent in the drought: keeping that water behind dams and putting it in the ground.
Why isn’t California capturing more runoff now?
When California gets storms like the atmospheric rivers that hit in December 2022 and January 2023, water managers in the state are likely to shake their heads and wonder why they can’t hold more of that water. The reality is that it is a complicated issue.
California has large dams and reservoirs that can store large amounts of water, but they are usually located in the mountains. And once they are almost full, water must be drained to be ready for the next storm. Unless there’s another reservoir downstream, much of that water goes to the ocean.
Video captures flooding from record rainfall on the last weekend of 2022.
In more populated areas, one of the reasons rainwater is not automatically collected for large-scale use is because initial runoff from roads is often contaminated. Flooding can also lead to flooding of the septic system. That water should therefore be treated.
You could say, the collected water does not have to be drinking water, we can just use it on golf courses. But then you need a place to store the water, and you need a way to distribute it, with separate pipes and pumps, because you can’t put it in the same pipes as drinking water.
