El Niño 2015

"The rainy season commenced on the 8th of November, and for four weeks, with scarcely any intermission, the rain continued to fall very gently in San Francisco, but in heavy showers in the interior. According to the statement of a Grass Valley paper, nine inches of rain fell there in thirty-six hours on the 7th and 8th inst. Whether, it is possible that so much rain could fall in thirty-six hours I will not decide; but it is certain that, the amount was great, for the next day the river-beds were full almost to the hilltops. The North Fork of the American River at Auburn rose thirty-five feet, and in many other mountain streams the rise was almost as great. On the 9th the flood reached the low land of the Sacramento Valley."[7]


The city of Sacramento suffered the worst damage due to its levee, which lay in a wide and flat valley at the junction of the American and Sacramento Rivers. When the floodwaters entered from the higher ground on the East, the levee acted as a dam to keep the water in the city rather than let it flow out. Soon the water level was 10 feet (3.0 m) higher inside than the level of the Sacramento River on the outside. Dozens of wood houses, some two stories high, were simply lifted up and carried off by the flood, as was "all the firewood, most of the fences and sheds, all the poultry, cats, rats and many of the cows and horses". A chain gang was sent to break open the levee, which, when it finally broke, allowed the waters to rush out of the city center and lowered the level of the flooding by 5–6 feet (1.5–1.8 m). Eventually the waters fell to a level on a par with the lowest part of the city.[7] From 1861 to 1862, the state capital was moved from flooded Sacramento to San Francisco.

The U. S. Army Corps of Engineers in their planning for Southern California could not have made use of palaeoclimatic and archaeological evidence recently published in the Journal Holocene. Here Dr. Arndt Schimmelmann, senior scientist of the Department of Geological Sciences at Indiana University along with his colleagues found evidence for cyclic simultaneous flooding not only in Southern California, but also in Mesoamerica and South America.

These findings, published in 2003, were based on sediment cores taken in the Santa Barbara Basin. These cores contain tell tale sedimentary deposits, called varves, and they date back 2000 years. Measuring the thickness of the varve gives an index of associated erosion during that particular year. These have occurred in approximate 200 year intervals centering during the following years: 212, 440, 603, 1029, 1418, and 1605. It is observed that bicentennial flooding in the Santa Barbara area was ‘skipped’ only three times and never twice in a row. The quasi-periodicity of approximately 200 years for Southern California floods matches the approximate 200 year periodicities found in a variety of high-resolution palaeoclimatic archives, and more importantly a 208 year cycle of solar activity and inferred associated changes in atmospheric circulation. The last skip was in the early 1800s leading the authors to conclude: “we foresee the possibility for a historically unprecedented flooding in southern California during the first half of the century.” (Schimmelmann, 2003 p.770)