Rising sea level could flood the twin tunnels shortly after construction

Submitted: Apr 29, 2016
Badlands Journal editorial board

 Following the widespread oceanic observations (1) that ice packs everywhere are melting much more quickly than at first predicted, and that seas are consequently rising more quickly, Chris Clarke, the author of these two articles, puts the Delta tunnels project into the context of a Delta rapidly flooding with seawater. Viewed in this context, the tunnels project looks like the height of futility, its possible only purpose being to squeeze one more building boom out of Southern California and stimulate the production of almonds in the San Joaquin Valley to the point where every grower goes broke from over-production.







Sea Level Rise Could Come Much Sooner Than You Think

Chris Clarke





It was just over a week ago that we reported on a study of melting of the West Antarctic Ice Sheet, which seems to be adding more water than we'd expected to the world's oceans. According to that study, melting off the West Antarctic is expected to boost sea levels by about a meter by the end of this century, bringing the total increase in sea level from all sources to two meters — six and a half feet — by 2100.

As it turns out, that recent news might already be obsolete, and far too optimistic. In a presentation at the Risk Management Society's RIMS 2016 conference in San Diego April 12, a top scientific official with the National Oceanic and Atmospheric Administration said that recent, as-yet-unpublished data from Antarctica suggests that sea levels could rise three meters — almost ten feet — by the middle of the century.

Margaret Davidson, NOAA’s senior advisor for coastal inundation and resilience science and services, told conference attendees that "the latest field data out of West Antarctic is kind of an OMG thing.” Davidson said that data shows sea level rise could reach three meters by 2050 or 2060, a much steeper rise happening far sooner than even the most catastrophic scenarios currently available in peer-reviewed journals and the far more conservative estimates published by the Intergovernmental Panel on Climate Change. That steep a rise in sea level would put significant parts of many California cities underwater in just two or three decades.

California is, theoretically, preparing for the effects of sea level rise, but not at a pace that satisfies sea level specialists. The state's planning relies on sea level rise projections that fall well below the three meters by 2060 Davidson suggests as a possibility. The California Coastal Commission, for instance, uses a 2012 summary from the National Research Council that suggests most of California will see sea level rises of between 18 inches and five and a half feet by the end of the century. As the Orange County Register's Aaron Orlowski reports this week, some affluent coastal communities are fighting efforts to prepare for even that much smaller amount of sea level rise.  

Why the discrepancy between the recent data reported anecdotally by Davidson and the formal pronouncements of the National Research Council and of the IPCC, which in 2013 was forecasting half a meter of rise by 2100? According to Insurance Journal reporter Don Jergler, Davidson told attendees in San Diego that the difference was due to the methodical nature of scientific study and peer review. 

"By the time we get out the [IPCC] report, it’s actually synthesizing data from about a decade ago,” said Davidson.

That's not all downside: the longer process also helps scientists avoid making rash judgments based on seemingly alarming data that turns out not to be as bad as it appears at first glance. It may be that the "OMG" data NOAA is getting from Antarctica actually results in less, and slower, sea level rise.

"The latest field data out of West Antarctic is kind of an OMG thing.” — Margaret Davidson, NOAA

That's worth hoping for, because three meters of sea level rise by 2050 or 2060 would be catastrophic for many parts of the world, including California. And 2050 isn't that far away. Sober forecasts of a meter or less of sea level rise by the end of this century are alarming in the abstract, but few people reading this in 2016 will be around to witness it. But mid-century? That's close. Children born this year will be in their early 40s in 2060. 

What would three meters of sea level rise look like in California? Southern California won't be as hard-hit as many places around the world, where millions of people live within a few feet of sea level in cities with no barriers between their residents and the surf. Southern California's coastal bluffs will protect much of the region's valuable real estate from direct inundation by three-meter-higher seas.

Most, that is, but not all. San Diego west of Interstate 5 is at risk, with low-lying neighborhoods like Barrio Logan and Mission Bay well within the inundation zone. Northward, anywhere there's a coastal estuary or creek we can count on the ocean growing new fingers to extend inland, with seawater flooding what had been irreplaceable freshwater marshes. South Bay shoreline communities from Huntington Beach to Terminal Island will be at risk of flooding: in some places land subject to inundation stretches halfway from the ocean to the 405. Venice and Santa Monica will lose their beaches. About half the Naval Air Station at Point Mugu will be at risk of flooding. So will about a third of downtown Carpinteria and the Santa Barbara airport.

That's some expensive real estate potentially going underwater in your children's early adulthood, but north of Big Sur is where the real changes to the map will be taking place. We can say goodbye to Monterey's Fisherman's Wharf neighborhood, for starters. The mouth of the fertile Salinas Valley will become a bay, as will the Pajaro River floodplain as far inland as Watsonville.

The Bay Area will be almost completely changed. Hilly San Francisco will be spared the worst of the damage, though it will lose UCSF's fancy new campus in the southeast part of town at Mission Bay. Downtown San Rafael will be underwater. The Bay will reach to Petaluma, Napa, and Fairfield — three cities well inland of the current Bay shore. The flats in Richmond and North Richmond, now populated by some of the Bay Area's least-affluent communities, will be underwater. Point Richmond will become an island a mile offshore. Oakland will lose its port, its airport, and many square miles of its most affordable housing in West Oakland and near the Coliseum. Between Hayward and Union City, a broad arm of the Bay will reach nearly to the base of the hills. Along the Peninsula, essentially everything east of Route 101 will be gone. So will downtown Milpitas.

And the most spectacular damage will be east of the Bay, in the Delta, as we mentioned in our recent piece on sea level rise and the Peripheral Tunnels. In that piece, we discussed the damage wrought by two meters of sea level rise. Three meters would be far worse. We could expect open water from West Sacramento — which would be lost without public works intervention — to Tracy, 60 miles south. Downtown Stockton would be gone. So would many miles of Interstate 5, which would skirt the east shore of the Sacramento Sea.


Interstate 80 flooding in the Delta, 2005 | Photo: Patrick Berrysome rights reserved


If the data from West Antarctica is as dire as NOAA's Davidson suggests, then California is faced with a staggeringly difficult series of choices. Building enough earthworks and levees and dikes to protect every single square mile of developed land under the three-meter mark by 2050 seems an impossible task: even if it were technically feasible, the cost would be astronomical.

And there are a few things to keep in mind. The potentially inundated areas listed here were mapped by  assuming the ocean was simply three meters higher. This method, referred to in sea level rise jargon as the "bathtub model," doesn't account for things like storm surges, seasonal floods as swollen rivers meet raised estuaries, or local variations in sea level due to phenomena such as El Niño. It also doesn't reflect the fact that once the Pacific reaches the three-meter mark, it'll keep rising from there.

There's also this: to get three meters of sea level rise by 2050 or 2060 we obviously have to reach one and two meters of rise sometime before that. Which means that — if Davidson's suggestions bear out — we're going to have our hands full in the lowest-lying areas, like the Sacramento Delta, very soon.

If Davidson's suggestions bear out, in fact, we will relatively soon be engaged in a public conversation about which parts of coastal Calfornia we abandon to the Pacific and which we harden with levees and breakwalls. If California's history is any indication, we're going to have to fight hard to keep real estate values from being the main factor determining what gets saved and what gets submerged. 

Or we could stop dumping greenhouse gases into the atmosphere, and minimize the damage to our coastlines. Just a thought.



New Sea Level Rise Study Calls Delta Tunnels Into Doubt

Chris Clarke


California homeowners will know the feeling. You shell out a huge amount of money for a place, and then suddenly you find yourself "underwater" -- owing more than the property's worth. 

But it isn't just that metaphorical fiscal water Jerry Brown's California Water Fix project may find itself under. The at-least-$17-billion public works project, intended to divert Sacramento River water around the Delta to the giant pumps that send that water south to farms and cities, may well find its proposed tunnel intakes under three or four feet of seawater by the end of the century. 

That's according to a study published in late March in the journal Nature. The study suggested that the West Antarctic ice sheet, which is melting faster than anticipated, will likely cause a meter of sea level rise by the end of the 21st Century. When you add that to other factors causing sea levels to rise, that means California's Bay and Delta may well see sea levels two meters higher in 2100 than they are now -- about six and a half feet of average sea level increase. And that may well push saltwater well past the planned intakes for the California Water Fix's tunnels.


At issue is a recent study by climate scientists Robert DeConto at the University of Massachusetts Amherst and David Pollard at Pennsylvania State University, published in the journal Nature in late March. The study, which examined the little-understood effect of melting surface ice on thinning continental ice sheets, suggested that Antarctic ice sheets could add enough water to Earth's oceans to raise sea levels as much as a meter by 2100, with that rise in sea levels accelerating sharply thereafter.

That boost in sea level is in addition to all the other things causing our planetary ocean to rise: the increase in melting of the Greenland ice sheet, melting of mountain glaciers, and thermal expansion of ocean water chief among them. With the increase in Antartica's estimated contribution to sea level rise, the world's oceans could well be 1.5-2 meters higher in 2100 than they are now, with that rise increasing at a faster pace in subsequent decades.

DeConto and Pollard suggest that by 2500, Antarctica's melting ice might well raise sea levels by 15 meters, or just under 50 feet. Add that to the seven meters of so a melted Greenland would likely contribute by then, and we're looking at sea levels 22 meters higher — 72 or more feet — in the year 2500 than they are today.


That more distant forecast would mean a very different California. A giant inland sea would cover the Central Valley from Yuba City to Merced. Most low-lying cities in the Bay Area would be destroyed, as would much of Long Beach and Orange County, and the Sea of Cortez would extend beyond Interstate 10 near Indio. Millions of people now live in parts of California that would be inundated in sea water if sea levels rise 70 feet by 2500, and the waters would cover important transportation corridors as well.

But we don't need to wait 484 years for this newly projected sea level rise to have a devastating impact on California. That impact may become significant in just a few short decades. And an almost certain casualty of that rise is a project that ironically has pointed to sea level rise as one of the reasons for its existence.

Rising seas threaten the state's existing system for getting fresh water from north to south. As it works now, huge pumps in the south Delta essentially suck water from the Sacramento River through a network of channels and sloughs in the interior of the Delta. When the water reaches the pumps, it's siphoned into aqueducts for the Central Valley Project and the State Water Project, which send the water to farms and cities to the south.

The relevant problem here is that most of those sloughs and channels flow past levees that protect large islands whose surfaces are below sea level. Rising seas threaten to overtop those levees. When they do, or when either earthquakes or simple entropy causes the levees to fail even without rising seas, the resulting floods of those low-lying islands will pull brackish water into the Delta from San Francisco Bay, and that brackish water will likely contaminate the fresh water heading for the pumps.

The much-lauded and much-criticized project currently called California Water Fix by its partisans in government and the Bay Delta Conservation Plan by wonks with a historical memory, but generally called the Peripheral Tunnels by everyone else, is ostensibly intended to solve this problem. Three large intakes along the Sacramento River between Courtland and Clarksburg would shunt Sacramento River water into twin 30-mile tunnels, each of them 40 feet wide, that would be buried 150 feet below the surface of the Delta. The project, which the state estimates would cost $15 billion (though critics charge its cost over the next several decades could be four times that), will be capable of delivering almost five million acre-feet of the Sacramento's water to the pumps each year.

Critics have blasted the project as a way to ensure that water exports from the Delta will continue regardless of the actual amount of water in the Sacramento, to the detriment of species like the Delta smelt and the Sacramento River winter-run Chinook salmon. And this week, the group Public Employees for Environmental Responsibility chargedthat the state has spent millions of dollars in federal funds on the project that was supposed to go to improving habitat for the Bay Delta's beleaguered wild fish. A federal probe into those allegations is gearing up.


But the new Nature study on sea level rise due to surface melt from the Antarctic ice sheets calls the whole point of the project into question. If sea level can be expected to rise by as much as two meters by the end of this century, with rise speeding up in the decades to follow, the project as described in its official documents would seem to be teetering on the edge of obsolescence before the first shovel of earth is dug.

The reason? Barring heroic measures, the area where the project's water intakes are to be built will likely be underwater not too long after 2100, and perhaps well before. The communities of Courtland and Clarksburg each sit on levees on the Sacramento River's east bank, built by the river's natural flow and augmented by human effort, that hold the flow of the Sacramento River a few meters above the surrounding countryside.  At Courtland, the Sacramento's surface is around 20 feet above sea level. A thousand feet east in the outskirts of Courtland, the land sits just six or seven feet above sea level, and it drops off to sea level and below in the middle of Randall Island. At Clarksburg, eight miles upstream, the river is a few feet higher, but the surrounding land also dips below sea level.

Consult the report here to see the maps: https://www.kcet.org/redefine/new-sea-level-rise-study-calls-delta-tunnels-into-doubt


If we can truly expect sea level to rise two meters by 2100 and keep going, there's a very good chance that California Water Fix's expensive intakes will be surrounded by salt water well before the end of the century.

Here's a screen shot of the northern Delta courtesy the sea level rise mapping engine at firetree.net. The blue overlay shows areas susceptible to flooding assuming a rise in sea level of just one meter:


The northern Delta flooded by a meter of sea level rise | Image: firetree.net

I've highlighted the stretch of the Sacramento River between Clarksburg and Courtland with a bit of red. As you can see, the potentially inundated lands in the Delta push up against the east edge of that stretch of river pretty hard -- and that's where the three intakes for the Peripheral Tunnels would go.

Here's the same area with two meters of sea level rise:

At two meters of sea level rise, the inundated area has grown to encompass the whole stretch of river where the intakes would be located, aside from one high spot about midway between Clarksburg and Courtland, approximately where the second of those three intakes would go.

Putting the intake in that high spot might not help matters much. For one thing, the intakes' location was chosen based on the assumption that they'd be adjacent to a freshwater river flowing past dry land and seasonal freshwater marshes. But at a meter of sea level rise, salt water would be pushing well into the northern Delta. How far north would that saltwater reach? That depends in part on how much water's flowing out of the new mouth of the Sacramento River, which at one meter of sea level rise would be right around the Yolo Bypass and Interstate 80. In wet years the river might well push the so-called "mixing zone" well to the south of the intakes' proposed location. In dry years, tidal pressure may well push salt water up around the intakes.

As long as the level containing the river holds up, that's not necessarily an insoluble problem. But increasing inundation will make those levees more prone to failure. Rivers work ceaselessly to take the easiest possible route to the sea, and if the sea is lapping up against the far side of a 50-yard earthen berm, it won't be long before the river decides not to flow past it for 30 or 40 miles.

If sea level rise were to stop there, a highly engineered and intensively maintained solution to keeping those intakes salt-free might be possible. But no one expects sea level rise to stop there. With seas as much as 22 meters higher by 2500, that's an average annual sea level rise of .05 meters — a meter every 20 years, or about two inches per year. It thus might not be too long after 2100 that sea levels have risen three meters above their current levels, which would completely surround the proposed intakes with water of questionable quality:

You may be wondering whether California Water Fix's planners had anticipated the possibility of sea level rise in their analysis of the project. The answer: yes, but only to a limited degree. While this month's Nature paper definitely underscores the increasing likelihood that seas may rise more than we expected, and sooner, DeConto and Pollard aren't the first to suggest the oceans may be more than a meter higher by 2100. In the 2013 Draft Environmental Impact Report /Environmental Impact Statement for California Water Fix, the authors state:

As much as 167 cm (66 inches) of 32 sea level rise is projected for the California coast and Delta region by 2100.

That said, the underlying assumption in that 2013 Draft EIR/EIS seems to be that sea levels will rise about three feet by 2100 — less than a meter.


...even a meter of sea level rise puts the intakes in jeopardy, unless the project includes a significant investment in earthworks to keep the Sacramento River flowing unsullied by salinity up to and past those intakes. There was some discussion in development of the Draft EIR/EIS of moving the intakes farther north to get them out of the way of the next century or two of sea level rise. But there's a problem: Get a little ways north of Clarksburg and you run into the outskirts of Sacramento, and construction of intakes and tunnels in that congested, high-real-estate-value city would send costs through the roof.

There's a limit to how much time we could buy by moving the intakes north, of course. If we get that 22 meters of sea level rise by 2500, those intakes would have to be up in Glenn County to stay high and dry.

None of this should be seen as a slam dunk dismissal of the California Water Fix tunnels...  inundation of the area surrounding the intakes doesn't necessarily mean those intakes are doomed to suck saltwater. There's the above-mentioned possibility that levees could channel the Sacramento River to the intakes. They would half to be pretty bulletproof as levees go: a failure would mean cutting off water to the southern half of the state. 

There's the possibility — though likely a slim one in a warming world with smaller river flows — that the Sacramento's fresh water would hold the intruding salt water at bay well downstream of the intakes, at least for a while. 

And there's the possibility that we as a species will suddenly get our act together and halt our emissions of greenhouse gases, to limit sea level rise to the amount we've already locked in, however much that may turn out to be. Though whether that's any more likely than building a series of unbreakable river levees is a matter for conjecture. 

And truth be told? If we want to build more secure levees in the Delta, there are a whole lot of existing ones that could use our attention.




National Geographic

Oceans Will Rise Much More Than Predicted, NASA Says

Predictions from a few years ago already are outdated. “Sea levels are rising faster than they were 50 years ago, and it's very likely to get worse,” one scientist says.

By Tim Folger


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