Floods of words and pictures

Watching Charleston's city council at work

Even using low-ball estimates of sea level rise and looking out just a few years from now, visualizations of flood risks facing Charleston, SC are alarming. Here's a picture of the combined flood risk (a substantial, Hugo-level storm arriving at the same time as a very high tide in 2050) facing the upper west side of the historic peninsula:

That's The Citadel on the left, the Medical District in the middle, a lot of businesses and houses on the right, all transformed into a series of small islands.

Here's that same 2050 risk a little farther down the peninsula:

Here's a third picture, this time of the combined flood risk facing the east side of the same peninsula in 2050:

If you don't know Charleston well, it may be hard to understand these images. But anyone can tell that many houses and businesses are submerged. Water seems to cover most of the peninsula. 

Now consider that these images are truly conservative. By 2070, Charleston will likely see nearly three feet of sea level rise, not one and a half. Then 3.5 feet by 2080, 4.4 feet by 2090, 5.3 feet by 2100. And the waters won't stop rising in 2100.* This is a risky place, where the lowest land is no more than four feet in elevation and where the seas are rising three times as quickly as they are elsewhere around the globe.

It's significant that Charleston is picking 2050 as its focus of attention. That allows the city to argue that "armoring" or "living shorelines" are both viable and worthwhile. Using 2050 allows many cities, not just Charleston, to push off the table far more important questions: How will the city cope with rapidly accelerating amounts of water slopping into its streets, houses, and businesses every year after that? Is it justifiable to invest in these short-term protection efforts? Wouldn't it make sense to gradually relocate at-risk assets and people? Roper St. Francis Hospital didn't wait: in 2021, it announced that it would leave the medical district of the peninsula, and last year it relocated to North Charleston, a separate city on much higher ground. 

Charleston's hardworking Chief Resilience Officer, Dale Morris, showed these pictures during a city council meeting earlier this week, using them to support the argument that the city needs to continue to engage in planning for protection to be build around the perimeter of the peninsula by the Army Corps of Engineers. "The Army Corps Project allows us to help to manage this, to sustain the peninsula," Morris said.

Several years ago, the idea that it would cost two or three billion dollars in infrastructure investments to protect Charleston was floated and, as Mayor John Tecklenburg put it during this week’s meeting, "There was nobody more substantial than Uncle Sam himself to help us." He added, "THE way, THE pathway to get federal help for all of this kind of infrastructure, is through the US Army Corps of Engineers." Construction costs have skyrocketed over the last few years, and no one really knows how much this project, or other projects, will cost in the end.

Charleston is in a rough spot. It has taken years to get to the point of negotiating a "design agreement" with the Army Corps that may allow the city to ask for an aesthetically pleasing wall to be built. There are lots of dependencies: once there's a design agreement in place, "Phase One," covering just the west flank of the peninsula, would take two to three years to design; only then would construction of that first section begin, and that would take seven more years.

Right now, absent major changes that the city would likely have to pay for, the wall would be a blank concrete structure, twelve feet high in many places, that would cross many streets and include dozens of gates that the city would have to pay to maintain forever. The wall would do little to address the increasingly severe high tide flooding and pummeling rainstorms that the city faces, and wouldn't protect the 90 percent of Charlestonians who don't live on the peninsula. The city's share of the project would cost north of $300 million, more than Charleston's entire annual budget. Money would have to come from many other sources, because the city's bonding capacity is less than half of that amount.

The city is also hoping to have Army Corps help with a Tidal and Inland Flooding feasibility study that would cover the entire population, not just the peninsula, and result, someday, in a host of proposed remediation projects for which it would compete for funding with other cities.

Bottom line: The only real source of funding to build new protections for Charleston at the moment is flowing through the Army Corp's process, and it's both slow in arriving and very conservatively applied. But in order to argue for staying the course with the Army Corps, the city has to show how dire the risks are--even from a highly conservative, limited perspective focused only on the peninsula. That's what made Morris's presentation particularly poignant this past week. He has to suggest how bad things are about to get, at the same time that the city has no real plan or funds available to ensure its residents can continue to lead thriving lives. 

Some of the pictures Morris used showed water slopping up onto the western areas of Charleston, built on marshy land west of the peninsula. That's where most Charlestonians live, in West Ashley and on James Island and Johns Island. There are no current plans to protect those areas (although Morris gamely points out that they have a plan to plan to plan to protect those areas in concert with the Army Corps). Take a look at this one:

The peninsula can be protected, these images suggest, by a seawall connected to a series of pumps and drains. But look to the left of the peninsula. All those orange areas? People live there. 

Councilmember Keith Waring picked up on this aspect of the pictures Morris showed. He said he asked an Army Corps employee what would happen to West Ashley in the future in the event of a hurricane. "I said, 'What about the homes over there?'" Waring said. "And he said, 'They'll have to be mitigated.' And I said, 'What form of mitigation is that going to take?' He says, 'Those houses are going to have to be lifted.'" Waring pointed out that people in West Ashley, James Island, and Johns Island don’t know this. He went on. "They don't even know that's a possibility." Lifting houses? At great expense? When roads around them are routinely flooded?

None of this is easy. But it would make sense to keep on the table, on a regional basis, the idea of careful relocation—before chronic flooding robs Charleston of its ability to plan at all.

==

* All of these estimates come from NOAA's "intermediate-high" predictions, which FEMA uses for most planning purposes. Take a look at the National Flood Insurance Program Coordinators’ Manual Addendum from 2021; see p A-43, second paragraph. Sea level rise estimates for years far in the future are necessarily somewhat uncertain, but all the arrows are pointing to rapidly accelerating rates of increase. NOAA will announce new high-tide flooding estimates next week, which will likely be higher than they have been in the past.