SANTA MONICA BAY AUDUBON SOCIETY BLOG

OK, a little historical perspective is needed. We’ve had some decent rain this 2018-19 season (unless your house washed away! – then it’s indecent) but it’s been larger in the past.

Here’s a link to two short films of Malibu Creek. According to Bob Purvey of EcoMalibu (where the films are posted) they were shot by Greg Hutto in 1995, month uncertain. Most likely, according to this report, it was the result of early morning rain on January 4 or the rains of January 9-10. [Note: EcoMalibu is permanently listed in our Links-Malibu Lagoon section in the right-hand column.]

Film 1 starts with a Red-breasted Merganser, cuts to the Pacific Coast Highway bridge and Malibu Creek, then cuts to the beach: https://www.facebook.com/EcoMalibu/videos/429339087839128/

Film 2 includes scenes from film 1, but also includes aerial maps for perspective:
https://www.facebook.com/watch/?v=1757252684296331

I ran across this document which reports on the 46 1000-year storms in California for 1862-1995 (that’s a bit more common than I expected, but the explanation is immediately forthcoming).

A 1000 year rainfall is one that occurs on the average once in a thousand years at a given site. This is an event in which the maximum storm rainfall is approximately five standard deviation above the average annual maximum event. With a 1000 rain gages we should expect an average of one 1000 year rainfall each year; if rainfalls were independent events- which they are not. A single storm can effect many rain gages therefore the measurements are not independent.

I have found only 46 storms which could be classified as 1000-year events in just over 147 years, based mainly on the daily rainfall readings. If hourly records were considered there would be many as the short duration extremes seem to be much more variable than the once a day rainfalls. The 1000 year one day rainfall expressed as a percent of the mean annual precipitation varies from 15 percent in the north west corner of the State to 165 percent in the south east corner.

On the storms of January, 1995, it relates:

Storm of January 4, 1995
Large rainfalls occurred in San Luis Obispo and Santa Barbara Counties during January. A new high rainfall was reported for Santa Barbara of 8.00 inches on January 4,1995 was reported in Climatological Data. This would have been the largest one day rain in their 125 year record; but it turned out to be a key entry error. The actual record for January 3, 1995 was only 2 inches. The highest ever daily rainfall for Santa Barbara was 6.95 inches on January 25, 1914. The notable rainfall for Santa Barbara this month was the 6.10 inches on the January 10, 1995.

Storm of January 7 to 13, 1995
Record breaking rainfalls occurred during the six days from January 7 to 12, 1995 on the west side of the Sacramento Valley. Fifty stations reported the greatest ever six day total rainfall. Cobb in the Clear Lake Basin received 35.18 inches in six days. The largest return period, from the records collected, was for Greenville in the Feather River Basin where 30.50 inches in six days had a return period of 2400 years. The main precipitation for this storm series was located in a band extending from Clearlake northeast to the Lake Almanor Region. Another band of high rainfalls extended from Whiskeytown north to the Mc Cloud region in the Upper Sacramento River Basin.

Storm of January 10, 1995
Embedded in the January 7 to 12 storm was the January 10,1995 event northeast of Sacramento. The peak 24 hour rainfall was 7.57 inches at the Granite Bay Country Club rain gage. This peak 24 hour storm consisted of 3 separate rainfall sequences; the first from about 7 to 11 PM on the ninth, the second and heaviest from 4 to 8 AM on the tenth and another burst of rain from about 1 to 5 PM.

Return periods represent the average time in years between storms of a given magnitude. They are calculated for stations with well organized and readily available rain records; hence they are not available for all records. The largest return period from the January 10 storm was 4000 years from 5.63 inches of rainfall at Rancho Cordova. This was from the rain gage of Joe Fierria, who kept a rain record there for 28 years. Thirty eight stations reported the greatest ever one day rainfall. Twelve Sacramento area stations reported over five inches of rain in one day.

The January 10,1995 storm in the Sacramento area was a low elevation event some what similar to the Columbus Day storm of 1962, when 5.5 1 inches fell on October 13,1962 at Citrus Heights. Unlike the 1962 Columbus Day storm however, the January 10, 1995 rain storm fell on saturated ground. It was preceded by eight days of rain. High antecedent rains preceding record rainfalls resulting in devastating flooding in the Sacramento area centered on Linda Creek which flows through Roseville and Rio Linda.

The storms of January 1995 extended from Humboldt County in the north to Riverside County in the south They caused a total of 740 million dollars in damage along with 17 deaths. Extensive debris flows occurred on Santa Barbara County.

The oldest storm event reported in California:

Storm of December 23 to January 21, 1862
The flood of 1862 we know to have been real, even with inadequate coverage of rain records, because [of] the size of the temporary lake that formed in the Central Valley .The Central Valley reportedly swelled up to a size rivaling that of Lake Superior before draining off into San Francisco Bay. William H. Brewer (1930) of the Whitney California Geological Survey wrote from San Francisco on Sunday, January 19, 1862, “The amount of rain that has fallen is unprecedented in the history of the state.—-The great central valley of the state is under water – the Sacramento and San Joaquin valleys – a region of 250 to 300 miles long and an average of twenty miles wide, a district of five thousand or six thousand square miles, or probable an area of three to three and a half millions of acres!”

Brewer writes of the Central Valley on February 9,1862, ” Nearly every house and farm in this immense region is gone. There was such a body of water-250 to 300 miles long and 20 to 60 miles wide, the water ice cold and muddy-that the winds make high waves which beat the farm homes in pieces”.

On October 4,1861 the Red Bluff Independent reported: “Six months have elapsed since rain has fallen at Red Bluff. This has been the hottest, driest season since California became a State. On Sunday something happened in Red Bluff which nobody has expected or wanted. Dust blew in every crack. It came in showers, people breathed gallons of dust and grit every time they opened their mouths.” On November 7,1861 the Independent wrote ” The mortality of cattle was high, they were starving.”

The Red Bluff Independent states that on December 10,1861 the drought was over and flood damage was extensive. The Red Bluff Beacon reported; “Even though California received tremendous damage, Oregon suffered more, The Williamette Valley completely overflowed and a town was swept away. Crescent City California was nearly swept away.”

A Belgian miner Jean -Nicolaus Perot (1985) left the gold fields to settle at Portland Oregon in time to witness the flood there. He writes, ‘The peaceful Wllamette became, by the fifth of December, an impetuous torrent; leaving its bed, it upset and carried away the establishments which bordered its bank. It was, for two days, a curious and heart-rending spectacle: the river was covered with strays of all kinds, trees, animals, fences, provisions, houses, sawmills, flour mills all that was floating pell-mell, and passed before Portland with a speed of three leagues an hour.”

Rainfall was recorded at only a few stations in the lower elevations in 1862. The heaviest rains were recorded at San Francisco where 28.25 inches occurred in 30 days. This was 6.48 standard deviations above the mean rainfall for 30 consecutive days with a return period of 37,000 years. Sacramento had 19.33 inches in 30 days with a return period of 2,200 years.

McGashen and Briggs (1939) indicate that the river stage on the American River at Folsom was 8 feet higher than in 1852, this was higher than any other known stage. A notable feature of the flood was the prolonged period of flooding in the lower Sacramento Valley from December 13, 1861 to about February 1,1862.

A report from the Stockton Independent Record quotes a Dr. Snell of Sonora who reported 30 inches of rain at Sonora, in 10 days. This would be 7.84 standard deviations above the mean and a very rare event.

Brewer reported that, “At Los Angeles it rained incessantly for twenty-eight days– immense damage was done–one whole village was destroyed. It is supposed that over one-fourth of all taxable property of the state has been destroyed.” —Brewer kept in touch with the State Treasurer and news of the dwindling state government income because he was having long delays in being paid for his work.

There you go – Lake Superior in the Central Valley.
[Chuck Almdale]