FutureStructure

Capturing El Niño, Part I: The Tech that Harnesses Storms

El Niño will bring much-needed moisture to the Golden State. But how much of that moisture will the state be able to use?

by / December 14, 2015

Five years into a drought, salt is choking the roots of California’s grapevines. The water lines at reservoirs holding drinking water have receded to historically low levels. Gigantic fires have gobbled up swaths of forest, incinerating homes along the way.

Good thing climatologists are tracking a massive El Niño storm system they predict will dump precipitation all over the state.

It's too bad California is still in the process of setting up a system that can capture more of the coming storms’ potential benefits.

Water management experts across the state are working to build a system — made up of both “soft” infrastructure such as interagency agreements and “hard” infrastructure such as water level sensors — that promises to help them more efficiently use the precious resource, including the capturing, treatment and use of stormwater to refill reservoirs and underground aquifers.

In the future, some of those experts envision a system where water managers will receive forecasts of coming rainfall, and they'll work together to clear the way to capture and store as much of it as possible. That would reduce the need to pump water across the state and would ensure a much more resilient supply in the case of a drought.

The state won’t have that system in place for this winter’s El Niño. But it’s working toward that system so it will be ready for future ones.

How to measure

To capture more rain, it helps to know when it’s coming and where it will fall.

Technology is making that easier. As an example, Arthur Hinojosa, chief of the Department of Water Resources' Division of Integrated Regional Water Management, points toward improvements in California scientists’ ability to monitor “atmospheric rivers” — planet-sweeping moisture flows in the sky that can portend precipitation dumps. According to Hinojosa, researchers have figured out a way to use earthquake monitoring machinery to gather data associated with atmospheric rivers and use that information to help better predict weather events that affect watersheds. The state also is working on new atmospheric river monitoring stations to get an even clearer picture of them.

Meanwhile, the National Weather Service is always working to improve forecast quality by collecting more information. The service’s Meteorological Assimilation Data Ingest System has allowed it to pull together data from a wide range of sources, including commercial airplanes and improved road-level weather monitors that state departments of transportation use to pinpoint the location of snow and rainfall. The Federal Highway Administration is working on tapping into unused data from cars, starting with fleet vehicles, to add even more information to forecast data — through cars’ external temperature sensors, for instance. All of that adds depth and pinpoint granularity to the data that informs weather forecasts.

All of that is important for watershed management in California because real-time weather information can impact water managers’ decisions and allow the system to work more efficiently.

“Knowing the size of that next storm, you can actually evacuate some of your storage to get your system ready for the next storm,” said Mark Hanna, a water resources engineer with the water management consultant Geosyntec.

Making that information more useful means putting data into a cloud that multiple entities can access. Data could come in from forecasting entities like the National Weather Service, as well as from hard infrastructure in the system — in the greater Los Angeles area, Geosyntec is working to install more water-level sensors at various parts of the watershed to help augment that information. That means, theoretically, that everybody downriver of the storage basin releasing its reserves ahead of a storm will know what the release will do to the river level.

“Then we’re able to process that information and make [announcements] such as, ‘Don’t go in the river’ or, ‘Go in the river at your own risk,’” he said.

How to manage

Los Angeles has been capturing stormwater for more than a century, but most of the infrastructure put in place to control rainfall has been constructed with the goal of preventing flooding — a strategy that doesn’t always put the water in usable underground aquifers.

Leadership at Geosyntec believes that with new technology, the city can capture far more stormwater than it ever has before. In the company’s plan for the Los Angeles Department of Water and Power's (LADWP) stormwater capture strategy, which the department has adopted, Gesoyntec estimates that about 6 percent of the water flowing across the city’s surface is infiltrated into aquifers that supply water.

But by investing in more stormwater capture infrastructure, that number could increase 22 to 31 percent.

LADWP’s current target is for stormwater capture to make up 3 percent of its water supply by 2035.

Hanna said that the presence of “real-time control” technology would rapidly inflate the amount of stormwater captured in L.A. County. The concept of real-time controls involves building a system where sensors tell water managers from minute to minute exactly how much water is in key parts of the system, how fast it’s moving, or the temperature, for example. Water managers could then use that information, along with weather forecasts, to better know when to evacuate storage basins and take other steps so that a watershed has the capacity to store as much water as possible.

Stormwater capture is a big deal because the city is famously dependent on distant rivers and deltas — as of June, the city reported that only 19.6 percent of its water came from local sources. Imported water, run through hundreds of miles of pipes and pumped over mountain ranges using massive amounts of energy, costs a lot more than local water: For water purchases in its 2014-15 budget, LADWP set aside $343 million — about 23 percent of its total spending.

But there’s another piece to the puzzle. Some rain falls complacently into reservoirs and spreading grounds; most of it has to be directed along human-made channels to those places. Along the way, it will be running along streets.

As it turns out, streets are dirty.

It’s not just an issue of garbage, according to Geosyntec water resources engineer Ken Susilo — though trash certainly is a problem. Water that’s run along L.A.’s streets also shows up bearing films full of nasty bacteria. Another big pollutant in the water is copper.

Researchers know where the bulk of the copper comes from — cars. Brake pads are often made of copper, and brake pads melt over the lifetime of a car. So especially in a car-dependent city like Los Angeles, that copper winds up covering the streets, and stormwater picks it up as it flows toward the drains. The metal is toxic to phytoplankton, which is a major food source for water-dwellers.

But the issue of bacteria is a little trickier. According to Susilo, the source of unwanted bacteria in stormwater is often unclear. Without knowing where the stuff is coming from, it’s difficult to figure out the most effective and efficient way to clean it up.

One possibility would be to simply set up a mechanism to run stormwater through a natural filter: the ground.

“If you had a flood control channel, [one option would be] putting an inflatable dam on it and a hole in the side of the channel, and sending the low flows into that hole and removing the trash and of course the pollutants, and then filtering it and then putting it into a system underground, for example … it just percolates into the ground,” he said. “If it can’t percolate, you can do what’s called dry wells, where it percolates through rock.”

The filtration process, however, gets easier if water managers can figure out where the offending bacteria is coming from. Then they could either clean it at the source or prevent it from entering the water in the first place.

As is often the case with new technology, Susilo said a big barrier to doing any of this is the up-front investment the projects would require.

“If you just look at the pollution side, you’re looking at multibillion dollar price tags, and that’s money that’s just not available right now,” Susilo said. “But if you link it with a benefit and don’t think about it just as a cost, you’re actually harvesting a commodity.”

He sees a growing appetite for such projects in the L.A. area. Municipal water plans are calling for more data gathering, while agencies are planning big projects to allow them to use more local water — for example, the Water Replenishment District of Southern California’s proposed Pico Rivera purification plant.

Even with the possibility of more public funding on the horizon, Susilo said there might be better ways to go about securing funding for projects that would allow Southern California to keep, use and reuse more of its water.

“Looking forward, we’re going to have to figure out a way through, in addition to doing things in the public sector, we’ll have to look at public-private partnerships, because that’s going to force the results,” he said.

Even with all of that technology in place, it doesn’t have nearly as great an impact if the right people don’t have access to it. The technology becomes more valuable if there’s soft infrastructure in place: If the entity evacuating a storage basin lets others who will be managing the water they evacuate know beforehand what will be happening, the downstream managers can plan accordingly.

“Now you’re better managing resources at your site, and that’s great for you, but it doesn’t really help the region unless everyone’s doing it,” Hanna said. “So that’s the … plus of a networked system.”

Read Capturing El Niño, Part II: The System that Works Best

Ben Miller Staff Writer

Ben Miller is the business beat staff writer for Government Technology. His reporting experience includes breaking news, business, community features and technical subjects. He holds a Bachelor’s degree in journalism from the Reynolds School of Journalism at the University of Nevada, Reno, and lives in Sacramento, Calif.