Wednesday, January 21, 2015

Today's king tides, tomorrow's normal high tide


Literally today's king tides - they're happening this week and people are encouraged to go out and document what sea level will be bringing us at some future point, so off I went on my bicycle this morning to snap some blurry pictures on my phone.

This picture has San Francisco Bay at my back, looking towards land in the South Bay (Mountain View). That slough-looking thing on the right would be Stevens Creek under normal conditions. Background buildings are part of the Googleplex on the right and NASA Ames/Moffet Airfield on the left.

Levee freeboard here is about two feet, so even a modest flood at this inconvenient time would be enough to overtop into the saltponds on the left (and other ponds you can't see on the right). That's not great but OTOH they're just ponds. Not a big deal so long as the overtopping doesn't destroy the levee.



My attempted artsy photo of the creek mouth, taken where the razor-wire fence ends the trail on the levee.  Normally the mouth is further down (this was my running route before my ankle gave up running). Reaching through the razor wire to take the picture wasn't easy.



Further upstream here, closer to Google campus and NASA Ames. The creek surface is significantly higher than the land surface, but the freeboard here is more like 6 to 8 feet. That would take a bigger flood, and I also happen to know that the creek has another breakout point a mile or two upstream that would relieve the flooding (onto somebody else).

Someday the Water District will fix that breakout though, so the increased maintenance cost and increased risk from elevated water levels will be permanent.

7 comments:

Everett F Sargent said...

Brian,

Here's something from NOAA on nuisance flooding:

"From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level rise"

http://onlinelibrary.wiley.com/enhanced/doi/10.1002/2014EF000272/
http://tidesandcurrents.noaa.gov/publications/NOAA_Technical_Report_NOS_COOPS_073.pdf
http://oceanservice.noaa.gov/facts/nuisance-flooding.html

James Cliborn said...

Just east in the delta lands near Stockton the sea level is already near street level. You want flooding, go look at the potential there!!! Also Humboldt Bay!!

Aaron said...

Look also at how the king tides flushed ice out fjords on Greenland.
see for example http://ocean.dmi.dk/arctic/satimg.uk.php

The Disko and the Kangerlussuaq areas are good places to look.

John said...

Website of the "California King Tides Project":

http://california.kingtides.net/

------

John Puma

Susan Anderson said...

OT, but fellow conies might like to go over and help Revkin's readers tell the difference between exaggeration and lies.
nytimes.com/2015/01/21/how-warmest-ever-headlines-and-debates-can-obscure-what-matters-about-climate-change/

(I say "readers" because Revkin is immovable, and as I said over there, his reaction seems emotional to me, and therefore unreliable.)

Susan Anderson said...

Oh, and your point on tides, we have this near my home in Boston (Fort Point). Have been observing since 1978, and it's getting dangerous, much of the city being about 3 feet above current sea level. I will have to move within the decade.
http://tbha.org/preparing-rising-tide-report

(Steve H is a friend, and that's two blocks away.)

Hank Roberts said...

In more recent news:
http://www.mercurynews.com/science/ci_27687593/california-drought-big-water-rate-hike-plan-reduced

"Tuesday's staff proposal called for softening the rate hike by adjusting the timing of transferring funds to do seismic repairs on Anderson Dam ...."

Because, hey, California droughts tend to end with significant flooding, and the forecast just went up for the likelihood particularly of large earthquakes, and who the heck is downstream?

http://www.mercurynews.com/science/ci_25385558/california-drought-dilemma-drain-anderson-reservoir-make-dam

What better time than when it's half empty, eh?

http://alert.valleywater.org/rgi.php