SOM: the bayarc rising tides competition
SOM: the bayarc   rising tides competition SOM: the bayarc   rising tides competition
aug 03, 2009

SOM: the bayarc rising tides competition

typical tidal conditions . the bayarc project image courtesy SOM

the san francisco bay conservation and development commission (BCDC) recently hosted an international architecture competition for ideas responding to sea levels rising in san francisco bay and beyond.

international firm SOM design was one of the six winners of the rising tide competition.

the bayarc is a minimal, lightweight and environmentally sensitive system designed to protect the san francisco bay area from periodic high water levels associated with sea level rise. it operates on organic principles of buoyancy and the structural efficiency associated with net membranes and tension. it is a concept that has the potential to eliminate billions of dollars in permanent levees and localized bay area flood protection without compromising the bay’s system of ecology and commerce.

SOM: the bayarc   rising tides competition flood threat conditions image courtesy SOMthe objective of the bayarc is to prevent the peak of extreme tide events while maintaining a natural tidal exchange between the ocean and the bay.

the bayarc consists of a submerged, cable reinforced membrane anchored to the seabed that utilizes a bladder embedded in a tensile leading edge fastened to structural pylons at the water’s edge. when deployed the bayarc floats to the surface and its tensile membrane creates a barrier stretching from the water’s edge to the sea floor.

the top cable of the bayarc is connected to anchors on each side of the golden gate bridge holding the membrane in place. a small amount of tidal or wave energy is captured by flotation devices at each anchor. this energy is used to compress air over time and is released quickly when the bayarc is deployed. the principle forces on the membrane result from drag during deployment as well as the hydrostatic imbalance due to the differential water level between the ocean and bay. the resulting gentle arc is a direct consequence of these forces. the arc’s curvature in plan directly echoes the arc of the golden gate bridge’s primary cables. the curvature is derived from the bay’s depth the arc’s material properties and span.

SOM: the bayarc   rising tides competition flood threat conditions – cut away view image courtesy SOM

SOM: the bayarc   rising tides competition l: the golden gate during typical condition r: cross section through golden gate while deployed image courtesy SOM

SOM: the bayarc   rising tides competition tensile membrane stress diagram showing relatively modest stress levels; greatest at center and least at ends image courtesy SOM

when the peak tide is projected to rise above a threat level, the bayarc is deployed. it remains deployed only until the high tide peak has passed ‘shaving off’ the peak into the bay. as the falling ocean tide approaches the bay, the bayarc drops and rest on the sea floor as the currents begin to reverse flow. as noted below projections for sea level rise by 2050 would require deployment for only a few house per day and only a few times per year.

  • Brilliant structural analysis! and by brilliant I mean the colors of the rainbow! Tensile membrane stress diagram? All it “shows” is a circular gradient. When are (we) architects going to realize that:

    1. It takes a Ph.D. in fluid mechanics to even begin to skillfully execute and interpret any kind of informative CFD, FEA, or MES analysis, not just some maya plugin, and

    2. just because you CAN generate a pretty rainbow diagram, it doesn’t automatically lend credence or validation to your design, in fact it appears equally reinforced in the orange as everywhere else, not more so as the diagram would suggest…

    If its not informative, please leave it out of this otherwise nice proposal. Sorry for the rant, pet peeve of mine on an exceptionally long monday…

    prettycolors says:

have something to add? share your thoughts in our comments section below.
all comments are reviewed for the purposes of moderation before publishing.

comments policy
designboom's comment policy guidelines
generally speaking, if we publish something, it's because we're genuinely interested in the subject. we hope you'll share this interest and if you know even more about it, please share! our goal in the discussion threads is to have good conversation and we prefer constructive opinions. we and our readers have fun with entertaining ones. designboom welcomes alerts about typos, incorrect names, and the like.
the correction is at the discretion of the post editor and may not happen immediately.

what if you disagree with what we or another commenter has to say?
let's hear it! but please understand that offensive, inappropriate, or just plain annoying comments may be deleted or shortened.

- please do not make racist, sexist, anti-semitic, homophobic or otherwise offensive comments.
- please don't personally insult the writers or your fellow commenters.
- please avoid using offensive words, replacing a few letters with asterisks is not a valid workaround.
- please don't include your website or e-mail address in your comments for the purpose of self-promotion.
- please respect jury verdicts and do not discuss offensively on the competition results
(there is only one fist prize, and designboom usually asks renown professionals to help us to promote talent.
in addition to the awarded designs, we do feel that almost all deserve our attention, that is why we publish
the best 100-200 entries too.)

a link is allowed in comments as long as they add value in the form of information, images, humor, etc. (links to the front page of your personal blog or website are not okay). unwelcome links (to commercial products or services of others, offensive material etc. ) will be redacted. and, ... yes, spam gets banned. no, we do not post fake comments.


a diverse digital database that acts as a valuable guide in gaining insight and information about a product directly from the manufacturer, and serves as a rich reference point in developing a project or scheme.

architecture news

keep up with our daily and weekly stories
503,120 subscribers
- see sample
- see sample
designboom magazine