So, I know the whole “plant thing” might not make sense to people who want to build bigger levees, and sea walls.
I’m trying to say we can’t manage with walls alone. Walls cost tons of money. We don’t know how tall to build them, or how fast. The earth is continuing to warm at a runaway pace. And we need to plan accordingly.
Currently, much of our shores are covered with riprap and sand that has been trucked into, and poured upon the surface of the shore. Sometimes the riprap is covered with a steel mesh, and cabled and bolted into place. But it doesn’t matter. Every time we get big waves, increasingly bigger pieces are being taken away from the shore.
Does it matter that this seems to happen faster in areas that were seeded by landfill? Do we need to worry about the marsh crust resurfacing? How far will saltwater “intrude” if left unchecked?
It would be more beneficial for us to focus on ensuring that our land is properly protected from erosion using natural methods of reinforcement. There are many concurrent benefits aside from erosion control that we will experience. We’ve already seen the perils of trying to fight against the encroachment with levees and walls when Tulare Lake reawakened. The dangers of levee failure or breach are more devastating than coastal flooding.
Consider the fact that surfaces covered with concrete do not absorb water, storm drains have a capacity, as do the pumps underneath our city used to keep the streets clear of what is actually an urban flash flood. That, at some point, we won’t be able to pump out this floodwater if the discharge point is already underwater itself.
Consider the fact that the pre-1900 [“alameda”] peninsula was encapsulated by lush, verdant, thriving wetlands; and that the south shores and bay farm coast were rich in oyster and clam beds.
Just like the rest of the earth, the Bay Area is a living, breathing, place. Our environmental systems sustain life in and around the bay. And floodwaters are supposed to be a regenerative force in the lifecycle of our ancient coastal blue carbon ecosystem.
Consider the fact that the San Francisco Bay, San Pablo Bay, Suisun and Grizzly Bays, have lost about 85% to 91.7% of their Historic Wetlands. The San Joaquin/Sacramento Delta has lost 96.8% of its Historic Wetlands.
Our bays are inextricably linked to our rivers, and the Sacramento-San Joaquin Delta. The delicate balance of our riparian habitats, tule, eelgrass, salt marshes, and tidal pools are crucial to our ecosystem’s capacity and resilience. These natural systems are responsible for filtering our water to support marine and estuarine wildlife, maintaining a healthy equilibrium in the brackish zone, producing land mass, stabilizing shorelines, and carbon sequestration.
The roots of fast growing estuarine and aquatic plants (like eelgrass, tule, etc.) stabilize shorelines by trapping sediment in their root systems and creating a buffer zone that absorbs floodwaters. The rising tide and sediment bury plants and form nutrient-rich (low-oxygen) soil which builds up the land mass, and gives rise to new fast-growing growing plants. The interring of carbon captured by the plants, which are buried in a low-oxygen environment, is the main mechanism behind what is now being referred to as coastal blue carbon habitats.
So, while walls might make sense, they aren’t practical. Levees and sea walls take years to build, and they’re a greater danger to the community than coastal flooding–because any breach would result in the immediate and violent expulsion of water directly into a borough or neighborhood, destroying the neighborhood, and injuring and possibly killing its residents. We can’t accept a greater long-term risk for the temporary reprieve from a disaster of our own making.
Restoring our ecosystems is the best chance we have to survive as a species. We need to learn how to terraform our own planet before we attempt to colonize another.
