Using Wetlands to Fight Sea Levels

The American Society of Civil Engineers (ASCE) has just released a report authored by 100 scientists and 21 management agencies which recommends mitigating the effects of sea level rise in the San Francisco Bay Area by using wetlands.

The report “The Baylands and Climate Change: What We Can Do”  focuses on the steps necessary to maintain a resilient ecosystem in the Bay area through 2100, and is an update of the 1999 report Baylands Ecosystem Habitat Goals, which calls for the establishment and maintenance of 100,000 acres of habitable tidal marsh.

It offers five strategies that the authors believe should be implemented in the Bay Area. Those strategies are to restore estuary-to-watershed connections, design complexity and connectivity into the baylands, increase coordination among baylands stakeholders, create plans that factor in ecological outcomes, and engage the citizenry in supporting these efforts.

The five strategies can be brought to fruition through 10 actions, the report says. These 10 include the first two items in the list of strategies, as well as restoring and protecting complete tidal wetlands systems; restoring the baylands to full tidal action; planning for the baylands to migrate; actively recovering, protecting, and monitoring wildlife; developing and implementing a comprehensive regional sediment-management plan; investing in planning, policy, research, and monitoring; developing a regional transition zone assessment program; and improving carbon management in the baylands.

With the creation of the correct elevation, “the marshes tend to look after themselves, given space and a supply of sediment,” said Jeremy Lowe, a senior environmental scientist in the resilient landscapes program at the Richmond, California-based San Francisco Estuary Institute. “We know how to do those relatively quickly and with good certainty about when and how it’s going to work.”

According to Lowe, it is critical to acknowledge, though, that the reestablishment and management of wetlands is an ongoing program, and not just a one-time project.

The concern is that with rising sea levels, the water is rising faster than sediment can be naturally deposited in the wetland areas. To combat this the report recommends developing a short-cycle, ongoing program so that every few years the navigation and flood management channels are dredged and the sediment from that work is placed a few inches deep on the wetlands so that the necessary elevations can be maintained.

Currently, channels are dredged on much longer time cycles.