Wednesday, November 28, 2018
Right now, there are 94 acres of shoreline beaches within Santa Barbara City limits; by the year 2100, 66 sandy waterfront acres of that will be gone, gobbled up by sea-level rise, triggered by climate change. That’s according to a draft report that details the impacts of rising sea levels on Santa Barbara between now and the end of the century.
The report, prepared for City Hall by consulting firm ESA, assumed that greenhouse emissions would proceed at their current rate without significant reduction. Its inventory of impacts also assumed that City Hall took no steps to mitigate or protect itself in the intervening years. Based on a medium-high risk scenario, the consultants concluded the sea level would rise by 2.5 feet between now and 2060 and by 6.6 feet by the year 2100. That will trigger a steady increase in tidal inundation that will have a profound effect on the shape and size of Santa Barbara coastal areas, public spaces, and municipal infrastructure located south of Highway 101.
The most obvious victim of all this will be the city’s bluff-backed beaches, such as Arroyo Burro and Leadbetter. Those beaches will be caught in a pincer action between the coastal bluffs and the encroaching tides and storm surges. By the year 2060, the ESA report suggested bluff-backed beaches might lose as much as 76 percent of their width. By 2100, they’d be 98 percent gone. Arroyo Burro would dwindle from its current width of 94 feet to 33 feet in 2060 and to zero by 2100. Shoreline Park will go from 30 feet to nothing. Low-lying beaches will hardly be immune. East Beach, the report indicated, will morph from its current width of 280 feet to 183 feet in 2060 to 32 in 2100.
Sea-level rise will hasten the rate of bluff-top erosion as well. That, coupled with tidal inundation and storm flooding, will affect 173 parcels of property — private and public — by the year 2060; that’s up from 99 right now. But by 2100, that number will be 1,241. Of those, 39 are hotels and motels, 716 housing, and 170 commercial.
Of all the municipal infrastructure plants located along the waterfront, perhaps none is more basic and directly threatened by sea-level rise than the city’s El Estero wastewater treatment plant. By 2060, the sprawling intrusion of ocean waters will be an operational issue for the facility. But by 2100, the problems will be terminal; the plant — as currently designed — will have been rendered “permanently inoperable.” The report listed the replacement cost of El Estero — in 2018 dollars — at $250 million.
The Santa Barbara Harbor itself will suffer a similar fate unless adaptive strategies are embraced and implemented. The report found that a 2-foot increase in sea level could cause operational problems. With a 6.6-foot increase — as projected by 2100 — “the harbor would not be usable in its existing configuration.” The most intense inundation issues would be experienced from El Estero to the harbor on one side and Highway 101 on the other.
A public workshop on the report and its finding will take place next week on December 5. The following Tuesday, December 11, the city’s special subcommittee on sea-level rise will meet to discuss the findings as well. “We don’t want to scare people too much,” said city planner Melissa Hetrick, “but the time to start planning is now.” With such big changes looming, Hetrick said she understood “the natural reaction of people to want to ignore it and not deal with it.” The longer the community waits, she cautioned, the fewer options it will have.
The good news, she stressed, is that options do exist. “There’s no magic engineering fix. It will be a blend of engineering solutions,” she said, “and removing development from areas we just can’t fix.” That menu of possible fixes won’t be on the table until sometime next spring. They include — but are not limited to — new sea walls, sand groins, and artificial reefs. The Laguna Channel floodgate height could be increased.
This study, Hetrick explained, was designed to provide a detailed inventory of likely impacts. It notably does not include, however, the impacts to the airport property, located in Goleta but on land in the City of Santa Barbara’s jurisdiction. That property is highly susceptible to flooding and is the subject of its own report.
Hetrick said the methodology used in preparing this report gave her a high degree of confidence in what would happen when sea levels reached certain heights. She was less certain of the dates when those heights would be achieved. But barring a significant change in global emission volumes, she was confident those new sea-level heights would be reached. "Will it take longer for sea level rise to get here?" she asked. "It might. But it will get here eventually. And when it does those impacts are likely to occur without adaptation."