SB County Flood Control presentation from the March 15 BEACON Board Meeting. Agenda Item # 9.
This presentation was given at the BEACON Board Meeting on Friday, March 15, 2019. The Powerpoint has been converted into a video:
King Tides are predictable, larger than normal high tide events that occur a few times a year when the moon is closest to the earth. A more scientific name is perigean spring tides. King Tides are interesting because they help to illustrate what more normal high tide events will look like in the future as sea level rise becomes more pronounced.
Sandshed: The Sand Is on the Move!
There is a constant flow of sand from the land into the ocean. Watershed run-off and bluff and hillside erosion bring sand to the beach. Sand grains travel southward down the coast, while finer particles of sediment are carried and deposited further out to sea.
Along the way, sand is washed ashore, temporarily resting on beaches, until it is re-suspended in the ocean by wave action or wind. The one-way journey down the coast ends when sand is blown inland forming sand dunes, or more commonly, when it flows into a submarine canyon. This deep underwater feature is essentially the dead end of a littoral cell, where sand is deposited for the long-term and, for practical purposes, lost.
A littoral cell is a distinct area of the coastline where sand enters the ocean, flows down the coast, and then is removed from the system. Permanent loss of sand occurs at the end of the littoral cell when it flows into a submarine canyon or, less frequently, when it accumulates on shore as part of a sand dune. The amount of sand available to…
Credit: Dave Hubbard and UCSB Sea Grant Team
USGS Coastal Erosion Report May 19, 2017 by Dan Hoover, Lead Researcher.
Report given during BEACON Board of Directors Meeting, Carpinteria, CA.
Article Writen by Nicholas Korady
August 3, 2016
For most of us, ‘home’ conjures a sense of safety and security. But a home is a fragile thing: vulnerable to quaking ground, rushing water, violent winds—not to mention, the volatility of finances and health. This has never been more true than in the time of climate change. The global thermostat of the home in which we build our homes is on the fritz.
As global temperatures rise, the polar ice caps have begun to melt, bringing up sea levels around the world. Simultaneously, a veritable witch’s brew of meteoric, atmospheric, and oceanic forces are creating more intense and frequent storms. If you live in just about any coastal region, your home is likely at risk from crashing waves and rushing floods.
“Households will be particularly affected by climate change, which will include uncomfortable summer heat waves and more frequent and severe floods and periods of drought,” write ARUP in a report entitled “Your Home in a Changing Climate,” which focused on threats in the United Kingdom. But a report isn’t necessary to convey this point when the images of the devastation Hurricane Katrina unleashed on New Orleans (and the rest of Louisiana, as well as Mississippi, Florida, Cuba, and the Bahamas) remain burned in our retinas. Or Hurricane Sandy. Or recent floods in England or the Netherlands, in Pakistan or India or China or Myanmar.
According to a recent paper in National Geographic, “As many as 13.1 million people in the United States will be in the path of flooding by 2100.” That’s three times the current population currently at risk. As more and more people flock to cities, the fallout from major sea-level related disasters will increase. So what can be done about it? Well, that depends—on where you live, your finances, and how quickly sea levels rise.
Take the task of protecting a home in New Orleans, for example. As Hurricane Katrina made abundantly clear, the city’s not-so-old defenses weren’t as strong as many assumed—particularly in economically-depressed areas. Byron Moulton of the New Orleans-based practice Bild Design explained that, if you look at an 1880 map of the city, its borders pretty much correlate with the borders of the regions of the city that were spared the brutality of the storm. Before the levee system was in place, all buildings rested on high ground. “In short time, people forgot about the risk,” Moulton explains. Now, large populations reside on ground that’s below sea level. And, while post-Katrina defenses have been added to the levee system, such as water pumping systems and new legal regulations, “we’re still at a little risk,” says Moulton. So how do you protect New Orleans homes against inevitable flooding?
“There’s lots of ways to do it, frankly,” Moulton told me. If you’re trying to preserve an existing structure, which are common in the historic city, then your best move is to underpin the building—essentially, jacking it up in the air, putting in steel beams and a new foundation. With new construction, pyles are the predominant strategy, but since a house on stilts can look a bit funny, different techniques are taken. New Orleans has soft clay soil, so pylons are driven down to where the ground is harder, a concrete cap is poured, and then a better-looking foundation laid on top. There are other measures possible, but this is one of the most popular. “The city requires it,” Moulton explained of a minimum floor height for new residential construction. “And FEMA funding is available for homeowners to lift their houses out of the floodplain.”
But if you’ve ever been to New Orleans, you’ve probably noticed its street life. Towering houses aren’t exactly conducive to front-porch culture. “You can’t turn your back on the neighborhood,” Moulton states. So Bild has employed other strategies, such as lifting one unit of a two-unit home while keeping the other on the ground, heavily anchored. If flooding occurs, the residents can take refuge in the elevated unit, while the other unit takes on water—intentionally.
This represents a combination of two of seven strategies outlined by Laura Tam of the San Francisco Bay Area-based group SPUR in an article entitled “Strategies for Managing Sea Level Rise”: floodable development and elevated development. Unfortunately, such strategies aren’t necessarily adaptable to San Francisco and its environs. “Some types of housing are never going to be able to withstand flooding,” Tam told me over the phone. And elevated development isn’t appropriate in earthquake-riddled California.
“A lot depends on a situational assessment,” Tam explains. Each particular area is different and what may work in one place may not work in another, even in the same city. “What the right strategy is for any one place depends on so much,” she elaborates. “What land use is like; what development looks like, now and in the future; what land values look like; whether uses are residential or commercial in nature; whether there’s a lot of elevation and topography or not; whether or not the shoreline can effectively host a large wall, which isn’t a viable thing to do in some places.”
And, in general, any conversation about mitigating the risks of sea-level rise for a private home necessarily involve planning and design at the regional level. “I think in a lot of places and, in particular, places that are settled densely, you have to look at more of a neighborhood or a district scale strategy. You can’t take a building-by-building assessment and flood-proofing approach.”
One such regional plan is “Living with the Bay,” developed by Brooklyn-based Interboro Partners for their winning Rebuild By Design submission. “The damage from Sandy was caused primarily by storm surge. But unfortunately storm surge is not Long Island’s only water-related threat,” they write. “Long Island faces serious threats from sea level rise, stormwater, and wastewater. The latter two threats are a major source of pollution: unfiltered stormwater runoff entering the bay by way of the region’s rivers and creeks threatens the bay’s ecology.”
Their comprehensive resiliency plan for Long Island, where 35,725 residents were displaced by Hurricane Sandy, takes a multi-pronged approach towards these multi-faceted, and co-constitutive, risks. The plan includes five strategies: “a protective infrastructure that doubles as a landscape amenity” for the very vulnerable barrier islands; new marshlands that help prevent erosion and can absorb water surges; “slow streams” to mitigate run-off; a green corridor built in part to encourage relocation further upland; and recovering and strengthening sediment displaced by Sandy.
But even such a comprehensive plan runs into other issues, such as legal and policy impediments. “Coordinated, regional decision-making is essential to the resiliency-building process. This is easy enough to say, but it is of course harder to achieve,” Interboro added over email.
“Because New York is a ‘home rule’ state, municipalities have the power to effectively chart their own course, which creates a barrier to the kind of regional decision-making that is required to adequately address regional issues like housing, transportation, or sustainability.
“Home rule can lead to redundancy (the State of New Jersey has 585 school districts), but it can also distract us from the simple truth that our fates are shared—that decisions made by and for one municipality have consequences for other municipalities in the same region. Disasters don’t stop at municipal lines; why should our responses?”
To help facilitate regional cooperation, Interboro has developed a strategy they call “grassroots regionalism”. In part, this involves figuring out ways that regional responses can also improve daily life on a local level, such as new recreation areas and more greenery. Interboro actively solicits community input in their design processes. Their “grassroots regionalism” also involves appropriating existing forms of regionalism, which they note are already happening all around us, such as sending-receiving relationships among schools or watershed management areas.
While disasters produced by the (larger) disaster of global warming and sea level rise threaten the solidity we associate with being at home, mitigating and preparing for them doesn’t have to diminish the quality of everyday life. In fact, disaster preparedness can improve neighborhoods and help foster a sense of community.
“Architecture that protects us from the occasional disaster (for example, a terrorist attack or a flood) too often requires us to sacrifice things we enjoy about everyday, non-disaster moments,” states Interboro. “It’s important that each and every investment in flood protection in one way or another improves everyday life. If we’re going to build protective structures, there is simply no reason not to add value to them so that they do more than merely protect.”
Archinect.com is The original source for this article and images.
(Click for original Article written by Nicholas Korody)
Global sea level rose during the 20th century, and projections suggest it will rise further and at a higher rate during the 21st century.
By Shawn Kelly
July 27, 2016
The West Antarctic Ice Sheet, which holds enough water to raise global seas by several feet, is thinning. Scientists have been warning of its collapse, but with few firm predictions or timelines. A study published May 16, 2014 in Science details how University of Washington researchers used topography maps and computer modeling to show the collapse of the West Antarctic Ice Sheet may have already begun. Eric Rignot, a glaciologist at the University of California, Irvine, and NASA’s Jet Propulsion Laboratory in Pasadena, California has said, “A large sector of the West Antarctic Ice Sheet has passed the point of no return” in terms of its retreat. Researchers say that the fast-moving Thwaites Glacier will likely disappear in a matter of centuries, raising sea level by nearly 2 feet. That glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another 10 to 13 feet of global sea level rise.
The public has heard mostly about climate change driven sea level rise impacts on economies and infrastructure, and to a lesser extent on habitat, but not much on recreational resources. Surfing is ideally suited as a key recreational resource to consider as one potentially significantly impacted by sea level rise. Of course, many surfers actually live in the coastal zonenand have to worry about issues more serious than the surf quality, like the potential inundation of their home, roadways, schools and businesses. Broader climate change impacts stand to affect surfing in a myriad of ways. To pick one example, changes in rainfall patterns will affect transport of pollutants to the line-up in urban areas and also affect the delivery of sediment to the coast which will subsequently affect the health of beaches and sandbars. Of these broader impacts, surfers seem to have been mostly focused on how climate change will impact wave climates, or the average condition of waves at a particular place, over a period of years. Climate change will result in changes in average wave heights, periods, and directions. But what will the beaches at which those waves will be arriving look like? Sea level rise alone stands to be the most significant impact to surfers, combined with the other broader climate change impacts affecting surfers.
Surfers are going to be on the front line of climate change driven sea level rise impacts, both via recreational impacts realized directly and wider impacts experienced as users of coastal infrastructure. In many cases those that live near the beach, impacts experienced as coastal dwellers. Surfers’ access and entry pathways to the surf will be affected: the beach, parking lots, access roads, staircases, etc., not to mention our homes, schools and places of business. Regional examples help illustrate. The Pacific Institute report The Impacts of Sea-Level Rise on the California Coast concludes that sea-level rise will inevitably “change the character of the California coast.” The Pacific Institute has a web based tool that shows populations and critical infrastructure at risk under various sea level rise scenarios. The available maps show coastal flood and erosion hazard zones under sea level rise scenarios.
Under the 2100 sea level rise scenario, my home near the beach in Oxnard, California will be threatened by inundation, as well as a lot of important infrastructure around my house. Of course, this won’t happen instantaneously, but rather on a continuing and increasing basis, with irregular spikes in impacts and inundation along the timeline. Correspondingly, the impacts are likely to be felt much sooner than the scenario offered by this image eight decades into the future.
Needless to say, adding one to three feet of water over our coastal ocean and surf spots in the next couple of decades to three quarters of a century is going to affect the surf quality. To illustrate in simplistic terms, take the example of a reef where the surf is highly tide dependent. A spot that currently breaks properly only on a high tide will in the future break on what is now the low tide once sea level rise is superimposed on its current condition. More critically, a surf spot that currently breaks only on a low tide will cease to break. Of course, beach breaks will be affected in potentially numerous ways, too. Coastal erosion will likely accelerate surf zones will become narrower and, as in the reef example, surf-tide relationships will change. All of our surf spots will be affected by the phenomena of coastal squeeze.
Coastal squeeze occurs as follows. As sea levels rise, coastal habitats like salt marshes, if in an entirely natural situation, would respond by migrating landward or “rolling back” to adjust their position to the best ecological fit for the new sea level. Rising land, development, or fixed man-made structures such as seawalls prevent or severely limit this landward movement, restricting the ability for beaches to adapt to rising sea levels. The coastal habitats, if present, are therefore squeezed between rising sea levels and fixed defense lines or higher land, therefore there is a risk the beach and adjacent coastal habitat may be lost altogether.
A significantly worrisome specter will occur along our urban beaches where people surf most: an unknown but foreseeable human response will unfold as sea level rises. Along these urban coastlines where significant infrastructure exists, communities will take action in response to sea level rise as valuable infrastructure is threatened; seawalls, probably the most likely short term human response and the one that stands to cause the most damage to coastal access, beaches, and surf quality, will proliferate. The human response to sea level rise also has large uncertainty associated with it in relation to timing, location, extent, and feedback loops. Sea level rise therefore presents both a direct and an indirect threat to our beaches, our surf, and our ability to access the surf.
What can you do as a surfer? Firstly, educate yourself on climate change and sea level rise and take actions that address the big problem: climate change. Reduce your environmental footprint through conservation, recycling and changing consumption patterns. Focus on your ability and approach to changing laws; for example, campaign for low carbon public transport and organize to elect officials who protect the environment. Secondly, be aware of the potential local impacts. In your coastal communities, educate decision makers and citizens and be a voice for decisions that have a long term view, account for sea level rise, preserve beaches and allow for shoreward migration of coastal habitat, decisions such as managed retreat of threatened infrastructure rather than placing seawalls to protect poorly located infrastructure.
“In the U.S., you have the best data set on what’s happening in the world, and yet it’s not used in public policy,” observed Robert Nicholls, professor of coastal engineering, University of Southampton, England. It’s a paradigm we surely need to reverse.
Reproduced with permission from Shawn Kelly.
Link to original article on The Inertia
The Future of America’s Greatest City is at Risk
Article written by Jeff Goodell
Source: Rolling Stone Magazine
July 5, 2016
It’s a bright spring day in New York, with sunlight dancing on the East River and robins singing Broadway tunes. I’m walking along the sea wall on the Lower East Side of Manhattan with Daniel Zarrilli, 41, the head of New York’s Office of Resilience and Recovery – basically Mayor Bill de Blasio’s point man for preparing the city for the coming decades of storms and sea-level rise. Zarrilli is dressed in his usual City Hall attire: white shirt and tie, polished black shoes. He has short-cropped gray hair, dark eyes and an edgy I’ve-got-a-job-to-do manner. Zarrilli may be the only person in the world who holds in his head the full catastrophe of what rising seas and increasingly violent storms mean to the greatest city in America. Not surprisingly, instead of musing about the beautiful weather, he points to the East River, where the water is innocently bouncing off the sea wall about six feet below us. “During Sandy,” he says, darkly, “the storm surge was about nine feet above high tide. You and I would be standing in about four feet of water right now.”
As Zarrilli knows better than anyone, Hurricane Sandy, which hit New York in October 2012, flooding more than 88,000 buildings in the city and killing 44 people, was a transformative event. It did not just reveal how vulnerable New York is to a powerful storm, but it also gave a preview of what the city faces over the next century, when sea levels are projected to rise five, six, seven feet or more, causing Sandy-like flooding (or much worse) to occur with increasing frequency. “The problem for New York is, climate science is getting better and better, and storm intensity and sea-level-rise projections are getting more and more alarming,” says Chris Ward, the former executive director of the Port Authority of New York and New Jersey, the agency in charge of airports, tunnels and other transportation infrastructure. “It fundamentally calls into question New York’s existence. The water is coming, and the long-term implications are gigantic.”
Wetlands, sand dunes and mangroves could protect shorelines more inexpensively than walls and bulkheads
Source: Scientific American
By Erika Bolstad, ClimateWire
July 6, 2016
Click here to read article: http://www.scientificamerican.com/article/living-shorelines-will-get-fast-track-to-combat-sea-level-rise/