Take a look at these pictures of the 2011 Japanese Tsunami and those on the previous blog cited above and let me know in the comments below if you really feel like relying on a sea wall to protect the low-lying sections of San Francisco Bay.
National Geogrphic photos from:http://news.nationalgeographic.com/news/2011/03/pictures/110315-nuclear-reactor-japan-tsunami-earthquake-world-photos-meltdown/#/japan-earthquake-tsunami-nuclear-unforgettable-pictures-ship_33287_600x450.jpg
Both Fukushima and New Orleans had sea walls, levees and the like. In the case of Hurricane Katrina, the levees had been neglected despite numerous warnings by responsible authoritative people. That is typical of the way the US treats infrastructures and has to be accepted as a given. In my mind, it is the most cogent argument against relying on sea walls or a levee. In the US , government is always a day late and a dollar short on infrastructure.
In Fukushima, the sea walls were well maintained and higher than the Tsunami but were overwhelmed by surges and "echos" as the incoming water waves reflected off of shore and underwater irregularities. The 2011 quake the caused the Tsunami was the largest shift ever recorded. Planning for the ones you can predict is of no help at all against those you can't predict.
Despite the biggest reclamation and restoration in the US, much of the SF Bay is land fill and perilously close to the water. Redwood Shores is a goner if the sea rises even a little, along with much of the Bay side of SF. The general rule is that water-side flat land = landfill. Landfill will shake like Jello in an earthquake. Old landfill is where most of the destruction occurred in SF during Loma Prieta earthquake. The idea that if the seas rise 3 feet we can build a 4 ft. wall and be safe is too bizarre to bother to refute. Nature works in surges with long periods of calm when it appears nothing is happening and it appears we can all go back to sleep followed by a catastrophe which was predicted then forgotten about.
After the disasters in the wake of Hurricane Sandy around NYC and neighboring areas a Dutchman was brought over to advise on how to mitigate and avoid similar future disasters as well as coping with rising sea levels. He comments on a number of proposals many of which could serve the SF Bay as well, instead of or in addition to a sea wall.
My favorites are MIT's
"...the Meadowlands of New Jersey is the pits of the Sandy-affected region. Flooding and surge came together there with contamination to create an ecological nightmare. But this is also an economic opportunity. ... The project involves creating a water system that becomes a natural reserve as well as a recreational amenity. It does this in part by enlarging the marshland, so that when there’s a surge, it can hold it, but at other times the water is getting filtered and cleaned.”
Resilience and the Beach. (Sasaki/Rutgers/Arup ) “This project considers the Jersey Shore. In fact, there is no single Jersey Shore. There are three zones: barrier islands, beaches and inland bay. Each has different demands. The project envisions the possibility of developing on the inland side of barrier islands, so they could serve the community and as barriers. It looks at the boardwalk in Asbury Park as a source of protection for the beach. And in inland regions, it would enhance the capacity of lakes to hold water in a storm.”
Living Breakwaters. (SCAPE/Landscape Architecture) “The goal here is to reduce risk for communities on the South Shore of Staten Island, which is highly vulnerable to surge and erosion. The scheme reconnects communities with the water, develops breakwaters and natural barriers offshore and creates new oyster reefs, which reduce storm surge, improve the water quality and allow for beaches to grow again.”