Coastal challengesMapping How Sea-Level Rise Adaptation Strategies Impact Economies, Floodwaters

Published 15 July 2021

Sea levels are expected to rise by almost seven feet in the Bay Area by 2100. New research shows how traditional approaches to combating sea-level rise can create a domino effect of environmental and economic impacts for nearby communities.

Communities trying to fight sea-level rise could inadvertently make flooding worse for their neighbors, according to a new study from the Stanford Natural Capital Project.

The research, published in Proceedings of the National Academy of Sciences, shows how seawalls constructed along the San Francisco Bay shoreline could increase flooding and incur hundreds of millions of dollars in damages for communities throughout the region. The researchers emphasize how non-traditional approaches, like choosing to flood certain areas of land rather than build walls, are smarter, more sustainable solutions for the Bay Area and similar coastal bay communities.

“It’s not practical to keep building taller and taller seawalls to hold back the ocean,” said Anne Guerry, chief strategy officer and lead scientist at the Stanford Natural Capital Project and senior author on the paper. Guerry is also a Senior Research Associate in the Stanford Woods Institute for the Environment. “Our goal was to show how the threat of sea-level rise is interconnected with the whole social-ecological system of the Bay Area. Communities need to coordinate their approaches to sea-level rise adaptation so we can find solutions that are best for the whole bay.”

Katherine Arkema, lead scientist at the Stanford Natural Capital Project, is a co-author on the paper

By 2100, sea levels are projected to rise by almost seven feet in the Bay Area. Millions of people live and work in buildings that are collectively worth hundreds of billions of dollars within the Bay Area’s projected sea-level rise zone. As water levels increase, governments are looking for ways to protect their communities and economies.

Following the Flow
The researchers used complex mathematical models to map how floodwaters – and the economic damages related to floods – would flow depending on where new seawalls were built. They found that blocking certain areas of the bay’s shoreline would be particularly damaging to communities throughout the region. For instance, if a seawall were built along the San Jose shoreline, communities throughout the bay, from Redwood City to Napa and Solano counties, would face an additional $723 million in flood damage costs after just one high tide, according to the models.

Damages to buildings and homes aren’t the only losses that could result from walling shorelines – it also can cut off habitat for important bird and fish species, limit the natural area available to store carbon and create water quality issues by destroying wetlands that naturally provide water treatment.