ENSO the Wet Season Ends (almost) – March 31, 2016

April 3, 2016

3–4 minutes

By Jay Lund

Summary of conditions

March 2016 has been unusually wet, and quite a contrast to February. The “Godzilla” El Nino this year has been a bit “Gonzo”, but overall has brought a welcome above average precipitation for northern California, after four solid drought years. The unevenness of the precipitation is some concern, and the depth of remaining surface and subsurface storage drawdown from the drought remains sizable.

Annual precipitation and snowpack are now about average overall for California. The largest reservoirs in northern California are in good shape, with sizable, about average, snowpacks waiting to trickle down in spring. Overall, total surface storage in California is about 2.7 million acre-ft below average for this time of year (improved from an 8 maf surface storage deficit in October). Groundwater will be recharging, as it should this time of year in most places, but groundwater is likely to remain drawn down in much of the southern Central Valley.

California remains in a drought, a bit. So far, the much-hyped El Nino has brought us largely average precipitation and snowpack. A huge improvement over the last few years, but not an excuse to forget the lessons of the drought so far. And who knows what next year will bring.

Here are recent highlights, with links to the California Department of Water Resources’ California Data Exchange Center (CDEC) at http://cdec.water.ca.gov.

Reservoir and Groundwater Storage Conditions

Major reservoirs in northern California are mostly healthy this year, but substantially emptier south of the Delta.

California’s total reservoir storage remains about 2.7 maf (about 2.7 full Folsom reservoirs) less than average for this time of year. This is a nice improvement from being 8 maf below average in October. Groundwater statewide will be making some recovery but will be a long way from recovering from drought in many drier areas south of the Delta.

The drought by 2015 depleted total storage in California by about 22 maf cumulatively or nearly a year’s worth of water use in agriculture. Storage is recovering during this wet season, but still has a good bit to go, probably 12-16 maf of drought storage drawdown remains, mostly from groundwater.

http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf

http://cdec.water.ca.gov/cgi-progs/reservoirs/RES

resMarch30

Precipitation and Snowpack

snowtable — Northern Sierra 8 Station Precipitation Index (inches) (tiny totals, compared to average, in yellow)

Precipitation in most of California is far superior to the last four years of drought. But we have had some very dry months (February) and some very wet months (March and January). Southern parts of California, south of the Delta, have had a smaller share of relative water bounty, but are in much better shape than last year.

Snowpack:

http://cdec.water.ca.gov/cdecapp/snowapp/sweq.action

http://cdec.water.ca.gov/cgi-progs/snow/PLOT_SWC

http://cdec.water.ca.gov/cgi-progs/products/swccond.pdf

Precipitation:

http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf – Sacramento Valley

http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf – San Joaquin Valley

http://cdec.water.ca.gov/cgi-progs/products/PLOT_TSI.pdf – Tulare Basin

ns_precip SJ_Precip tulare_precip

Concluding thought

Much better than the last four years, but still a bit of drought. A very wet March, and fairly wet December and January, has helped recover from a dry February and four years of drought. Northern California is in mostly good shape for the coming year. More southern parts of California are more stressed, but still far better off than the previous four years. Lingering drought effects will continue. A “Godzilla” El Nino is no guarantee of a drought-buster.

It is unclear if the next year will be a return to drought conditions, but the forecast for April so far seems mostly dry.

UC Davis’ drought seminar series videos are now available at: https://watershed.ucdavis.edu/education/classes/california-water-policy-seminar-series-drought

Jay Lund is Director of the UC Davis Center for Watershed Sciences and Professor of Civil and Environmental Engineering at UC Davis.

Further Reading

Paul Ullrich (Video): Drought in California: A climatological look at water in a semi-arid landscape. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, January 13, 2016

Jay Lund (Video): Drought and Water Management in California. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, January 6, 2016

Peter Moyle and Jay Zeigler (Video): Drought Impacts and Management for Ecosystems. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, February 1, 2016

Thad Bettner and Robert Roscoe (Video): Local Responses to California’s Drought. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, February 8, 2016

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4 responses to “ENSO the Wet Season Ends (almost) – March 31, 2016”

Rich Persoff

April 3, 2016 at 8:36 pm

“One swallow does not a summer make” nor does one average rain year when much more was expected from historical data entitle the author to indicate in any way the drought is lessened, ‘a bit improved’, etc. Do stop Cheerleading for “normal”; remember Joseph’s 7 good years and 7 dry ones? We should be hunkering down preparing for another series of low-rainfall years, not patting ourselves on the backs because reservoirs are not as low as they were last year!

Reply
1. gymnosperm
  
  April 4, 2016 at 8:11 am
  
  Please stop cheerleading your religious preconceptions. You yearned for “God”zilla, a clear sign from the heavens of displeasure with what you perceive as our sins. We got a gecko. A normal year.
  
  Try to focus on the data.
  
  Reply
  1. Rich Persoff
    
    April 4, 2016 at 10:21 am
    
    Whoa, Nellie, with those off-target slanders, assumptions, and just plain misreadings!
  2. gymnosperm
    
    April 5, 2016 at 8:25 am
    
    Slanders? Misreadings? You iwrite that Jay’s discussion of the season’s normalcy is cheerleading. I read that such “cheerleading” is a distraction from what you believe is the inevitability of future drought.
    
    No slander, no misreading, no sale in this quarter of the inevitability of continuing drought.