San Rafael Canal District: Adapting to flooding with a Super-dike
Author: Yilin Li and Yuetian Wang
Institution: University of California, Berkeley
Instructors: Kristina Hill and Deni Ruggeri
Studio: Just Zero: Visions for adapting urban districts in frontline communities around San Francisco Bay; Graduate Landscape Architecture and Environmental Planning; Fall 2021
Studio Partners/Collaborators: Ms. Terrie Green, local elected official and community activist, Marin City, CA; Aileen Thiele and Kristen Van Dam, East Bay Regional Parks District; Julie Beagle, US Army Corps of Engineers; Joel Horn, real estate developer; Warner Chabot, Director, San Francisco Estuary Institute
San Rafael was built on a former saltmarsh. San Rafael creek and canal flows through the area. The town houses the county’s largest population of low-income people and recent immigrants. Residents along the canal are especially vulnerable to flooding.
We propose to achieve a healthy, safe and low-carbon city by 2050, by (1) building a super-dike (super-dikes are wider, not taller than normal dikes, and allow housing to be built on top of wide terraces – as demonstrated in Osaka, Japan). Wetlands and oyster reefs could be built on the lowest seaward terrace of the dike. (2) Construct a new overflow channel for stormwater and high creek flows, that runs on the landward side of the super-dike and allows discharge from behind the dike. These two pieces would be built first, in phase 1. In phase 2, we propose to (3) re-grade corridors within low lying land to form channels that can discharge high groundwater and create habitat corridors and terraces for multiple ecosystems as sea levels rise, and (4) construct floating housing in areas with very high groundwater. Microgrids could be used for decarbonization throughout the re-built housing districts on the Super-dike and floating in artificial ponds and canals. Many jobs would be created by the re-construction and regrading of the community.
Our studio began by considering the physical, ecological and social context of low-income communities of color along the estuary shore of the San Francisco Bay. First, students mapped the armatures (topography, infrastructure, vegetation) that shape the flows of organisms, energy and materials throughout the region. We reviewed the history of redlining and restrictive housing covenants that left communities of color restricted to low-lying areas that are vulnerable to flooding. Then we learned about the process of sea level rise, and how it causes groundwater to rise also – making levees almost useless without pumps. Ecologists and environmental planners helped us understand the importance of mapping coastal flows within operational landscape units (OLU’s), which allow us to see how ecological adaptation can be designed to fit in a specific context. Next, we discussed neighborhood and district-scale systems in cities as a context for adaptation and decarbonization. We reviewed the Oakland Ecoblock project, which is designed to use solar PV to generate electricity and use flywheels to store it instead of lithium batteries. We identified references that helped us estimate the amount of carbon that could be stored annually in tidal marshes of the San Francisco Bay (1.5 US tons per acre), the amount of carbon stored in 40 ten-year-old trees (1 US ton), the carbon stored in grasslands by adding compost (1 US ton per acre), and the carbon stored in grasslands or ag lands by adding rock dust )1 US ton per acre). All of our references were regional, with the exception of the rock dust paper. We interpreted the justice goals of the GND as a need to provide access to housing and healthy environments, and the geographic stability provided by adaptation in place to rising seas and rising groundwater. Adaptation to gradual flooding meant conserving regional transportation corridors and building local bike and wildlife corridors, while increasing the number of housing units. Our decarbonization goals were to generate electricity or natural gas from renewables, while storing as much carbon in soil and vegetation as we could within the context of each urban district. Finally, we interpreted the goal of job creation as either temporary construction and planning jobs, created as a by-product of re-building infrastructure and housing, or permanent maintenance and small business jobs needed to sustain new park systems and energy systems. Our overall goal was to show that adapting to sea level rise and fire regimes in urban districts can be done, and that landscape architecture can lead in that redevelopment process. Landforms and vegetation patterns are the critical underlying armatures that will allow cities to adapt to a changing climate. We presented social systems that support racial and class hierarchies as both unethical and problematic for adaptation, since they maintain rigid social roles when flexibility and resourcefulness are needed. Landscape architecture can help to re-organize social systems around our shared appreciation of a healthy environment, our desire to be resourceful, and our compassion for each other across our differences.