By Susan Schwartz
President, Friends of Five Creeks
Susan Schwartz is an amazing watershed steward and local environmental organizer at the Friends of Five Creeks. We always love to partner with her!
For the Bay Area, many effects of global warming remain uncertain. But the greenhouse gases now insulating Earth mean that ice will melt, a warming ocean will expand, and sea levels will rise. Respected mid-range predictions indicate likely rises of about 10 inches by 2050 and 4 feet by 2100. Long term, or if higher predictions prove true, effects may be much worse.
Maps based on these predictions suggest the need to plan and act, not panic. In the East Bay, at 10 inches, many parks and marinas, some major infrastructure such as the Oakland Airport, but few homes seem likely to flood, even during storms and high tides. At 4 feet, flood potential moves into the Port of Richmond, industrial northwest Berkeley, and low-lying neighborhoods in San Pablo, Richmond, Emeryville, Oakland near the Coliseum, Alameda, San Leandro, and Union City.
Other areas face greater challenge, but the Bay Area is not standing idly by. Myriad studies are ongoing. New state and local rules point the way. For example, just-signed state law requires that all state infrastructure projects consider climate change. Actual projects also are moving ahead. These can take widely different approaches.
Nature can buffer the effects of rising seas. Creating or restoring marshes can slow down battering waves and surges from tides and storms. Thousands of acres of diked fields and salt ponds are being restored to wetland in the North and South Bay. Where such wetlands are impractical, “living shorelines” such as eelgrass or oyster reef, can do some of the work. Shores also can be sloped gradually to slow battering waves. The Oro Lomo project nearing completion in San Lorenzo will test part of this idea. But many such projects will eventually require raised levees behind them.
Another approach is retreat. Abandoning land to the sea may sound extreme, but the new Breuner Marsh Regional Park, south of Point Pinole, will let seaward land gradually flood. In San Francisco, redeveloping the former industrial Pier 70 backing into the Dogpatch neighborhood may entail grading a series of terraces that eventually could be underwater, with buildings set back at more than the 5.5’ elevation San Francisco now requires.
“Harder” engineering — raising sea walls and building new levees – may protect the many Bayside freeways, pipelines, airports, and sewage-treatment plants. Tide gates could protect narrow channels from flooding during high tides and heavy rains – for example, at San Francisco’s Mission Bay. The idea is not new: At Suisun Bay and Oakland’s Lake Merritt, tide gates can be closed to let water out but not in.
Developments that flood or float may seem futuristic. But people have long lived on houseboats. Many Russian River homes perch on stilts, and the Gulf Coast brought back old-fashioned elevated buildings after Hurricane Katrina.
On Tuesday, Oct. 18, UC Berkeley Associate Professor Kristina Hill introduces “Future Shorelines” — fresh ideas from around the world on how the Bay Area can adapt to rising seas. The free talk, part of Friends of Five Creeks’ Bay Currents talk series, is at St. Alban’s Parish Hall, 1501 Washington, Albany; refreshments 7 PM, talk 7:30 – 9 PM. Info here.
Image Credit: Friends of Five Creeks, and http://www.thesfnews.com/extreme-high-tides-in-bay-area-cause-flooding/24275
