Alameda leads Bay Area in assessing vulnerability from sea level rise
Published on November 18, 2020
Alameda leads Bay Area in assessing vulnerability from sea level rise
City releases cutting edge research on groundwater impacts from sea level rise
Alameda’s City Council has unanimously accepted a pioneering report on the effects of sea level rise on groundwater, pushing forward the science of integrated climate adaptation planning. The report, titled “The Response of the Shallow Groundwater Layer and Contaminants to Sea Level Rise” finds that rising groundwater levels are a hidden threat related to sea level rise. Download the new report at https://www.alamedaca.gov/files/assets/public/alameda-pio/slr2020.pdf.
Alameda, a low-lying island with portions built on fill and former marshland in the San Francisco Bay Area, is aware of the consequences sea level rise could have when floodwaters overtop the shoreline. This new report shines the spotlight on an additional and much less studied risk. Sea level rise can cause the groundwater table to rise, in some areas even above the ground, creating “emergent groundwater.”
“We identified emergent groundwater as a potential future hazard for Alameda when developing the Climate Action and Resiliency Plan,” says Erin Smith, Public Works Director for the City of Alameda. “The City wanted to get ahead of this issue – to better understand the risks and figure out how to address them while we still have time.”
Alameda’s new study finds that the areas at risk of future flooding increase by up to 25 percent when considering emergent groundwater and in certain areas this flooding occurs well before coastal floodwaters overtop the shoreline. Rising groundwater, even before it is emergent, will affect below grade infrastructure such as building foundations, basements, and utilities. Many homes throughout the city are already affected by groundwater, and sump pumps are commonly found in basements. It is expected more water proofing, sump pumps and foundation repairs/improvements will be needed.
Dr. Kris May, a coastal engineer and climate adaptation specialist with Silvestrum Climate Associates, who led the study for the City, noted that working on this issue was personal. “I live in Alameda and have already seen evidence of rising groundwater levels firsthand in my basement. My sump pump runs much more often than it used to, which concerned me. Thanks to Alameda’s willingness to dive into this issue, we now have information that can help us develop solutions and prepare ourselves.” The study makes recommendations for adaptation solutions to include in Alameda’s Climate Action and Resiliency Plan, such as amendments to local building codes to address floodproofing and guidance for homeowners regarding sump pumps.
The underground legacy of Alameda’s industrial and military past was also considered in the study. As the groundwater table rises, underground contaminants could be brought to the surface, which could have health implications for humans, pets, wildlife, and the Bay. Although many of the community’s contaminated sites have been cleaned-up, contamination remains. The study includes an assessment of where contaminants could be mobilized over time and presents a suite of strategies, including ideas to assist homeowners.
The City is also coordinating with the San Francisco Bay Regional Water Quality Control Board to better understand potential health risks, vulnerable areas, and evaluate whether additional measures are needed to keep the community safe. Michael Montgomery, Executive Officer with the San Francisco Bay Regional Water Board acknowledges the City’s efforts: “Alameda is focusing on an issue that has been on our radar but is very challenging to understand. Their forward-thinking actions are helping to move this conversation forward for the entire Bay Area. With proactive planning, we have an opportunity to protect vulnerable areas and critical infrastructure early, before adverse sea level rise impacts occur.”
“All shoreline communities in the Bay Area will likely face the same challenges of adapting to sea level rise and rising groundwater. The California Resilience Grant provides a wonderful opportunity to bring us together to brainstorm solutions,” says Mayor Marilyn Ezzy Ashcraft.
This new report can be downloaded at https://www.alamedaca.gov/files/assets/public/alameda-pio/slr2020.pdf. The next steps for Alameda include incorporating these new findings into the Climate Action and Resiliency Plan and working with regulators and the region to continue better understanding and addressing these issues.