Hearing tragic stories, such as those coming from Houston, the Caribbean, and Florida, of flooded homes, lost livelihoods, and destroyed personal possessions, our inclination is to blame nature. We often see quotes in the news such as “there was more rain than the models projected,” or “the river swelled too quickly for us to evacuate properly.” However, while forces of nature supply the winds, rain, and tidal surges, the severity of these events and their disastrous outcomes are the result of human intervention. And with climate change, we are going to see more such events in the future.
As an environmental planner focused on climate change adaptation, through my dissertation research I work to understand how to transform protective infrastructure to create multifunctional landscapes that can help mitigate these negative impacts. My investigation takes a three-pronged approach: assessing protective typologies, addressing issues of alignment, and exploring the costs of protection.
Assessing Protective Typologies
The first critical question I address is, ‘What does the shorezone currently look like and what are possible versions of a future shorezone?’ Analyzing data from the San Francisco Estuarine Institute, site visits, and case studies I find that the current bay wide shorezone is predominantly hardened structures that are static and are not as multifunctional as an ideal landscape would be.
There are sites however, such as the one depicted above in front of a residential neighborhood in East Palo Alto that are in fact multifunctional. This site works on a number of levels and provides the region with wealth of values: habitat, water storage, wave attenuation, carbon sequestration, recreational access, and aesthetic benefits.
In my research, I evaluated the following six physical proposals to adapt the shoreline to sea level rise: Aramburu Island, Novato Creek, Oro Loma, San Francisquito Creek, Solano County, South Bay Shoreline Study. I used three criteria for my analysis: 1) the project’s ability to address the highest rates of sea level rise, 2) the project’s ability to address flooding threats from all four directions, and 3) LAEP Associate Professor Kristina Hill’s infrastructure typology. Through this work I find that the current proposals for climate adaptation projects are shifting the bay toward a more multifunctional context, however this shift is only marginal and more is needed to meet future threats.
Addressing Issues of Alignment and Re-alignment
In the world of mapping and planning, drawing the line is a critical step. ‘Where is the edge of the flood zone?’ ‘What neighborhoods are most vulnerable?’ or, ‘Where should we place the floodwall?’ are just some of the questions faced by climate adaptation and hazard mitigation planners. However, when grappling with a slow-onset problem such as sea level rise, static single-purpose protection will not adequately solve this long-term threat. Instead, we need to shift our thinking and work toward a transformative path through different iterations of the future.
In my work I’ve developed a series of shoreline edges that align with current habitat zones. Shoreline A is the most bayward and represents the current front edge of saltwater marsh habitat and walled protective structures. Shoreline B represents the boundary between saltwater habitat and freshwater habitat. Shoreline C, the most landward, represents the back edge of the freshwater habitat. In creating these delineations we can start to strategize ways to align and re-align our bay edge to future scenarios.
Exploring Costs of Protection
Much of today’s climate adaptation research focuses on understanding the costs of inaction. In my work I look at the costs of different adaption strategies, such as levees and sea walls. To do so I integrate complex factors to more accurately capture costs of potential design types. Key factors include structural aspects of protection, land-purchasing costs, replacement factors, and design heights based on regulations.
Graph showing the range of potential costs needed to raise protective infrastructure to provide some protection for future sea level rise scenarios for each of the three shorelines described above. Costs are based on current infrastructure type — landform or wall — being raised to meet future water levels in a no-storm-surge condition and sea level rise scenarios. Information and access to the data is provided through UC Berkeley’s online data archive, known as DASH.
Through this work I find costs of static protection to be in the hundreds of billions of dollars. Based on a ratio of revenue to cost as an approximate indicator of a county’s ability to finance its physical shoreline adaptation needs, most counties in the San Francisco Bay Area will be deeply burdened by these costs. Alameda, Marin, and San Mateo Counties will be the least able to afford their adaptation costs while Napa, Santa Clara, and Sonoma Counties will be the most likely able to fund protective infrastructure. These high costs can be offset by using green infrastructure solutions such as a horizontal levees, however even these solutions are expensive. In light of these costs, the region will need to think creatively about unique financing strategies such as the development of resilience bonds.
For further work, see “Choosing a Future Shoreline for the San Francisco Bay: Strategic Coastal Adaptation Insights from Cost Estimation,” Daniella Hirschfeld and Kristina E. Hill, Journal of Marine Science and Engineering, September 2017.
