Flooded cars on roads

Flooded cars on roads

El Nino Through the Eyes of an Expert

Santa Clara University civil engineering professor Edwin Maurer discusses the near-record weather system of 2015-2016

For Northern California, a record-breaking El Nino weather system could be a blessing for drought relief, but brings with it the risk of flooding. Prof. Ed Maurer answers five questions.

1. Will El Nino hit Northern California? Probably. With typical El Nino storms, Southern California gets wetter-than-normal conditions; the Pacific Northwest gets drier-than-normal conditions; and we're sitting in the middle. So we're very dependent on where storms track. It can be a very slight perturbation in pressure systems that can drive storms farther north, farther south, or right smack into us.

2. If it hits Northern California will it be good for drought conditions here? For California’s water supply, we want the Northern Sierra to get wet, so the water is reserved in snowpack and slowly melts through May, June, and July, and can be captured or diverted and used for all kinds of things. Current projections are for a 40 percent, 45 percent chance of wetter-than-normal conditions, and about a 33 percent chance for normal conditions. The problem is, what gets left out of a lot of these forecasts is Northern California also has much better than average chances for a warmer-than-normal year.

3. So we should be prepared for what, water-wise? Wetter-than-normal conditions, but much of it in the form of rain, which means flooding. Think of it this way: if you fill the reservoir in January or February, then you get a big storm in March, you can't store that water. That then creates flood-control problems downstream, in places like Sacramento or Alviso.

4. What else? This scenario would ease the burden on farmers who’ve had to cut back on water and food production, and will recharge the groundwater to some degree. But it won't make up for all the pumping we've done. Historically, after droughts you can see groundwater levels rebound in wet years, but never enough to offset all the decline that had happened beforehand.

5. So what is smart going forward? Plan for droughts at all times, the way you plan for earthquakes. That means never going back to our pre-drought water usage—we’ve proven we can get by with 30 percent reduced usage. And keep finding ways—such as flooding agricultural land strategically, using percolation ponds or reclaimed water—to preserve and recharge groundwater more effectively. I think you're going to see a lot more agricultural technology being implemented. We live in a periodically arid place, and we need to live in a way that reflects our surroundings.