Sutro, Fog Catcher
And drought GIFs, naturally:
The dog days of reservoirs.
This is especially bad since we in California get the most of our water from the Sierra snowpack. Uh oh.
Hetch Hetchy is a geo-engineering marvel, but you have to start wondering what happens when the Sierras start looking like Baja California.
@mizmay reminds us that we actually have decent groundwater in SF.
These would be Islais, Precita and Dolores Creeks:
“the fresh spring waters indefatigably flowing on the eastern slopes of Twin Peaks are a wondrous geologic feature, of unknown origin and potentially great benefit to the city. This water comes in quantities and seasons unlikely to be associated with local rains. Further study is needed to determine its ultimate source.”
Of course, it’s always nice to have backups. This is why I demand that Ed Lee immediate tap the aquatic reservoir that is… @KARLTHEFOG.
There is a precedent to this in South America. Residents of Lima are building “Atrapa nieblas“, or fog traps. On a good foggy day they can capture 150 gallons of water.
We of San Francisco, being awesome, can do better than that. First some math. Fog contains anywhere between 0.05 and 0.5 grams of water per cubic meter. Karl, being Karl, is obviously 0.5 grams. Assuming half the city is covered in fog at a depth of 1000 feet (i.e. the top of Twin Peaks):
49 square miles / 2
= 63,454,700 square meters * 300 meters
= 19,036,410,000 m3 * 0.5 grams
= 9,518,205,000 grams = 9,518,205 kilograms = 9,518,205 liters = 2,514,440 gallons.
That’s a sphere of water 43 feet wide, or a cube 70 feet on a side.
Problem solved! OK, not really, as I do not have a realistic method to collect fog over half of San Francisco. However, a short term solution would be to retrofit Sutro into an atrapa nieblas:
Simulation of it in action:
(original photo via DailyKos)
A quick calculation shows that with a surface area of 300 by 300 meters, and a 22 mph wind (10 m/s), our modified Sutro could catch 100 gallons per sec.
Not too shabby, Sutro, not too shabby. If @karthefog is around for 12 hours, that’s over 4 million gallons!
UPDATE: Sarah Zhang wrote a great followup article over on Gizmodo about other fog catcheries: