Biology Reference
In-Depth Information
engulfed in water during extreme events. But as sea level rise intensifies,
the frequency and duration of flooding will increase. “Sea level rise maps
resemble what the bay looked like before the Gold Rush. When they were
diking and filling, they didn't bother to raise the new land very high. So
in some ways the bay is going back to where it once was, in short order,
except instead of the riches of wetlands and tidal flats developed over
thousands of years we may have a big reflecting pond,” says BCDC's
Goldbeck.
To keep pace with a growing bay, Goldbeck's agency has launched a
new climate change initiative. In 2009, BCDC published a vulnerability
assessment, which suggests that up to 270,000 Bay Area residents could
face flooding from the bay within their own lifetimes.
Noah Knowles, who worked up a series of inundation maps for BCDC
based on his USGS computer models, was particularly alarmed by the in-
creased risk to built-up areas. Today, about 68 square miles of these devel-
oped areas are vulnerable to yearly inundation; by 2099 the vulnerable
expanse will more than double to 140 square miles. For all types of lands—
from barren soil and cropland to wetlands and urban areas—Knowles cal-
culates that about 367 square miles is now at risk of periodic inundation,
and that this amount will increase to 485 square miles by 2099.
Most of the residential areas at risk lie in the South Bay. Here tides
swell to higher levels than elsewhere in the bay due to local hydrodynam-
ics and subsided lands. Protecting these areas—by building bigger lev-
ees—will be challenging and expensive. A bigger levee is also wider,
spreading the impact onto private lands, backyards, and out into the bay.
Areas like Foster City may soon qualify for flood insurance.
“If levees fail and your place is inundated every 100 years, you might
consider building there; if your place is flooded every month you're not
going to,” says Knowles. “As the water level rises and peak events get
higher, and mean water levels get higher, the old levees are more likely to
fail without substantial reinforcement.”
Also on the wet list are San Francisco and Oakland airports, the Bay
Bridge maze, long stretches of Highways 880 and 101, and the campuses of
Silicon Valley Internet giants. Areas where water historically flowed in and
out of sloughs or creeks are especially susceptible; for example, in and
around San Francisco's AT&T Park and Mission Bay, and Richmond's in-
dustrial port zone. Waves and storm surges could even reach into the
lobby of BCDC's own downtown headquarters on San Francisco's Embar-
cadero, which is built on a graveyard of Gold Rush-era ships.
Getting around could become a nightmare. Highways, railroads, and
bridge approaches—built as so many are along the shoreline—could also
go underwater. Flooding of other key elements of the region's infrastruc-
ture could be even more dangerous. Many sewage treatment plants dis-
