A new report has shown a hidden aspect of sea level rise that has been exacerbating flooding in the Bay Area, amid dramatic ocean swells and drenching atmospheric rivers.
The research, which was released on Tuesday, depicts places that could flood as a result of groundwater that is only a few feet or even inches below ground. This layer of water rises as thicker water from the ocean travels inland due to rising tides. Even before it reaches the surface, water can leak into basement cracks, penetrate pipes, or, more sinisterly, re-mobilize dangerous compounds buried underneath.
Communities that consider themselves “safe” from sea level rise might need to think otherwise, said Kris May, a lead author of the report and founder of Pathways Climate Institute, a research-based consulting firm in San Francisco that helps cities adapt to climate change.
“I started working on sea level rise, then I went into extreme precipitation, and then groundwater … but it’s all connected,” May said.
She noted that hot spots where the soil is already saturated with rising groundwater were some of the first to flood when a recent series of atmospheric rivers dumped record rainfall onto California.
The new findings are the result of an unprecedented joint effort by May, the San Francisco Estuary Institute (SFEI), UC Berkeley and a wide-ranging team of regulators, building officials, and flood-control agencies to identify where the groundwater along the bay shoreline is close to, or already breaking, the surface.
A set of searchable maps, available online to the public, zooms in on Alameda, Marin, San Francisco and San Mateo counties — the first of many jurisdictions that researchers hope will undergo this intensive data-refining process.
The maps build on a new but growing body of research. In 2020, another study led by the U.S. Geological Survey laid the groundwork for this issue along California’s 1,200-mile coast, and state toxic substances control officials have since started their own mapping efforts to better understand how rising groundwater might affect contaminated land.
This story was adapted from Gov tech.
