No, stemming the Golden Gate won’t save the Bay Area from rising waters

As climate-accentuated storms continue to hit the Gulf and Atlantic coasts, causing historic and all too often fatal flooding, it is imperative that the Bay Area take note and begin planning for the dangers that the climate change will bring California’s coastal communities. The Bay Area is unlikely to face epic hurricanes like Ida or Sandy, but we will face storms that will push huge amounts of seawater ashore. This will produce dangerous flooding throughout the bay which will only be exacerbated in the coming years by rising sea levels.

Recently, it was suggested that we study the construction of a storm barrier across the Golden Gate. In concept, this huge device would be lifted before storms to prevent high water from entering the bay.

At first glance, this seems an attractive solution, as we can focus our flood protection efforts and expenses on a small part of the shoreline, instead of protection tailored to the needs of each of our waterfront communities around the bay. .

Unfortunately, a Golden Gate barrier would only be an expensive temporary fix that would cause irreversible damage to the bay.

In the future, we will still have to rework our entire shoreline to achieve flood protection. As the Intergovernmental Panel on Climate Change recently described, sea level rise will accelerate in the coming decades. To cope with these rising seas and storm surges, by mid-century we will need to raise the barrier frequently – on the order of every month with the highest tides, and not just every few years. due to storms. This would begin to transform the San Francisco Bay from a vibrant estuary to a managed pond, generating major environmental impacts.

The bay’s ecosystem would suffer from gentle tides, accumulated sewage discharges, and massive algal blooms that would kill fish and wildlife. The wetlands that protect many of our shores would be destroyed without tidal currents, thus increasing flood damage (this is already evident in the Oosterschelde estuary in the Netherlands, where more than a third of intertidal habitat has been lost since the commissioning of a storm barrier in 1986).

Wetlands also improve water quality by filtering the waters of the bay. Their loss would exacerbate pollution and endanger protected species of fish, birds and mammals found in San Francisco Bay, such as the California Ridgway’s Rail, salt marsh mouse, and rainbow trout.

In the next century, the predicted rise in sea level would require the barrier to remain in place almost full time to provide flood protection, turning the Golden Gate into a dam. This would exacerbate the difficult problems mentioned above. Shipping in and out of the bay would only be possible by developing massive locks. The water exchanges between the bay and the ocean, which are essential to support fish and wildlife, dilute sewage, and carry water from rivers to the sea, would be eliminated. These ecological changes would cause further damage upstream in our local rivers and in the delta.

As the sea continued to rise, the dam would have to be raised, and a vital part of the region’s economy and quality of life would depend on an ever-growing collection of pumps, pipes and locks maintained in perfect working order. These complex structures would create an increased risk of flooding by rivers during heavy rain storms or by the sea due to a malfunction of a barrier.

The obvious response to this increased risk of flooding will be to raise dikes around the edge of the bay – precisely the action that the barrier was designed to prevent in the first place. And because the barrier would have damaged the wetlands that protect against erosion, the dikes would now withstand the full force of the waves and would have to be even larger.

A much smarter solution is for communities to bear the expense of planning to remodel their shorelines to accommodate the ocean’s rise over time. By optimizing solutions now, we will minimize the total cost over time. These solutions should include the continued restoration of wetlands which can provide protection against flooding, the construction of dikes and dikes where they are needed, and possible acquisition and change of use for low lying areas particularly. vulnerable. New infrastructure should be designed to adapt to the tides and storm surges of the future, and to meet the needs of all communities in a fair and equitable manner.

Projects are already being implemented around the bay to adapt to the rise in sea level, and these efforts will be all the more effective as the communities become more and more involved in their future. littoral. Regional success will be enhanced by the sharing of innovative approaches, technical expertise and coordinated awareness to attract federal resources (objectives of the Bay Adapt program).

By redesigning our shores, we can maintain for future generations the great benefits that our functional estuary offers us today, including flood protection, potable water, thriving maritime commerce, wildlife habitat, access to nature for urban communities and world-class recreation and tourism.

The Bay Area can be a coastal city that shows how to adapt and thrive in the face of climate change. Or we can be held captive in a deteriorating 20th century landscape behind a dam trying to hold back the ocean.

It is not a difficult choice.

Andrew Gunther is a member of the San Francisco Bay Area Water Quality Control Board and the Bay Conservation and Development Commission. Jeremy Lowe is a scientist in the Resilient Landscapes Program at the San Francisco Estuary Institute.

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