BETWEEN CITY + SEA: multi-trophic mariculture as urban intertidal catalyst
Urban waterfronts can do more than retain the land in spite of the sea. This design project explores and applies multi-trophic mariculture as a means toward enlivening and broadening the disappearing gradient between city and sea. Through the strategic integration of multi-trophic mariculture into a degraded and beleaguered public waterfront, this design research leverages the processes of sediment accretion and intertidal expansion to afford synergistic cohabitation within this living place and dynamic threshold.
Sand engine refers to the deliberate massing of sediment with reference to waves, currents, and drift patterns in order to leverage the drift cell’s established dynamics to carry and deposit sediment. This strategy was most famously employed at the Netherlands’ Zandmotor project, at a scale much larger than would be required at North Beach. North Beach’s drift cell once contributed to the formation of West Point. Today, however, a significant portion of the feeder bluffs up the drift cell are armored. There may no longer be enough sediment throughout this system to build up an intertidal gradient, even with armoring and sediment scour reduced along this beach. The proposed location of a sandspit is therefore southwest of Owl Creek’s entry into the Puget Sound.
The urban intertidal in Puget Sound consists of over 700 miles of armored shoreline. Across Puget Sound, armoring typically accompanies coastal development. This map describes areas of impervious surface within Puget Sound’s watershed in dark grey and shoreline armoring in red.
The spatial design I chose to elaborate is composed of a hybrid between cultivated terraces and a sand engine-fed nested groin system made of mussel posts.
1. TIDAL MARSH TO BRACKISH BACKWATER
1″= 4′ SCALE
2. BRACKISH BACKWATER TO MUSSEL POSTS
3. MUSSEL POST TO NORI CURTAINS
Mariculture as a spatial design tool is morphologically and performatively plastic.
It is a model that changes as maricultural agents become established and form habitat for other non-cultivated creatures. An integrated multitrophic aquaculture-based waterfront could go beyond retaining the land in spite of the sea. It could reestablish an interstitial space for the organisms that make the intertidal zone a living place and a living infrastructure for a terrestrial urban center. In this way, the intertidal zone is both a threshold and a place. In conventional waterfront design, the intertidal zone is summarily overlooked—it is rarely understood to be valuable as recreational space for urbanites, nor as performatively valuable as a softer form of shore protection infrastructure. As a result, the urban intertidal has been designed as the thinnest of spaces: a contour, a line, an edge.
In an urban world that is pressed for public space and in need of multi-faceted approaches to mitigating the uncertainty and risk at the water’s edge, mariculture as a design tool offers a medium with which to reconceptualize the threshold between city and sea as a place again.