... house by house, block by block, with millions of dollars at stake...

January 9, 2018 10:56 AM

In New York, Drawing Flood Maps Is a ‘Game of Inches.’ As FEMA revises the maps to account for climate change, deciding who is in the flood zone will be a battle with millions of dollars at stake. (SLNYT by David W. Chen)

Particularly interesting are the maps in the section 'Drawing the Lines in Canarsie,' where you can see a) where Sandy flooded and b) FEMA's and NYC's competing floodplain maps.

posted by crazy with stars (29 comments total)

I admit that I'm baffled as to why the city contested what looked like a more expansive flood-zone map right after Sandy. I've read the article, but still don't understand why they'd do that; what am I missing?

I checked myself on a few of the maps and saw that I'm just barely outside all the flood zones, as I suspected. I live near Wallabout Bay, which is on the north side of Brooklyn's landmass so it's got some protection from a storm surge; but it's also kind of in a channel where water would be pushed.

But even if the bay does flood - I'm about 600 feet up from the precise point where the land starts to slope up, and that may be what's sparing me. But I'm looking down the slope, to where they're building a whole bunch of fancy-ass condos right along the edge of the bay and in the Navy Yard, and....hmm.
posted by EmpressCallipygos at 11:05 AM on January 9, 2018

I admit that I'm baffled as to why the city contested what looked like a more expansive flood-zone map right after Sandy. I've read the article, but still don't understand why they'd do that; what am I missing?

The impact on property values in the new flood zone, I'd imagine.
posted by showbiz_liz at 11:07 AM on January 9, 2018 [11 favorites]

What are the non-coastal effects on watersheds from sea level rise ?

Newly inundated land will have a higher water table. The land next to the new coast line will also have to have a higher water table. And land next to that land … . Water table rise won't be uniform because the ground is not uniform. Will there will be changes in levels and flows throughout the watershed ?

When the outlets of rivers become part of the sea, that part of the watershed becomes flooded. Does this reduce floodwater storage capacity ? Will floods in the watershed be higher and last longer because the drainage outlet is in a state of permanent flood ?
posted by llc at 11:11 AM on January 9, 2018

The story is the same in every city. Updating FEMA maps is political (most cities just minimize funding so they can't afford to redraw the maps), flood insurance is expensive and required by few properties (only those with a federally backed mortgage- way below 100% of properties), and even in flood zones most people let it lapse if it is not required.

The impact on property values in the new flood zone, I'd imagine. I don't think it's property values exactly, but rather federal limitations on repair and construction.
posted by The_Vegetables at 11:11 AM on January 9, 2018

From the captions on the maps in the article

A new FEMA map would have forced thousands to buy insurance, and, the city said, sent property values plummeting. ... The city’s alternative map would affect far fewer. FEMA agreed to hold off to negotiate.

Time and tide wait for no man.
posted by Nelson at 11:27 AM on January 9, 2018 [9 favorites]

I admit that I'm baffled as to why the city contested what looked like a more expansive flood-zone map right after Sandy. I've read the article, but still don't understand why they'd do that; what am I missing?

The issue is really whether Sandy was a 100-year storm or a 500-year storm. If it was a 100-year storm, then the 100-year flood zone, for the moment, should coincide with where Sandy's floodwaters reached. But the city appears to be arguing it was not a 100-year storm so the new 100-year flood zone should be more conservative, while agreeing to project out where that zone may expand to in future years. Meanwhile the city is working with neighborhoods throughout the city to increase flood resiliency, meaning elevated structures, flood gates at entrances, and similar measures.
posted by beagle at 11:30 AM on January 9, 2018

Millions? I think they spelled Billions wrong.
posted by sexyrobot at 11:46 AM on January 9, 2018 [4 favorites]

But even if the bay does flood - I'm about 600 feet up from the precise point where the land starts to slope up, and that may be what's sparing me. But I'm looking down the slope, to where they're building a whole bunch of fancy-ass condos right along the edge of the bay and in the Navy Yard, and....hmm.

I live in one of those fancy-ass condos near Wallabout Bay, right at the point where the land starts to slope up. Mine is a mixed income development created by a partnership between a non-profit developer and the city. Two of those buildings are city lottery rentals; another is condos, 72 out of 94 of which were through the city lottery. Another is supported housing for formerly homeless. Most of the tenants came from Fort Greene and Clinton Hill. You can bet we know about being so close to the flood zone. In my building at least, it's come up in meetings and on the gmail group. I do know that our boiler and electrical stuff is on the roof, not the basement.

It's a little bittersweet. I came from way uphill in Clinton Hill, which survived Sandy with a few downed trees but otherwise untouched. Now I can afford to stay in the neighborhood forever, but I do wonder what's going to happen so close to the river.

There are real fancy-assed condos going up right on the river closer to Williamsburg.
posted by maggiemaggie at 12:24 PM on January 9, 2018

The buildings that are going up in The Navy Yard proper are all office buildings.
posted by maggiemaggie at 12:27 PM on January 9, 2018

I came from way uphill in Clinton Hill, which survived Sandy with a few downed trees but otherwise untouched.

I was in Clinton Hill during Sandy, too. Kitty corner from Kum Kau. The worst thing to happen other than the trees was the downing of the NYCPets sign. It was shocking how relatively unperturbed the area was.
posted by grumpybear69 at 12:29 PM on January 9, 2018

Apropos of something or other, Kim Stanley Robinson's New York 2140 is an excellent book and an entertaining read.
posted by JohnFromGR at 12:30 PM on January 9, 2018 [2 favorites]

> I came from way uphill in Clinton Hill, which survived Sandy with a few downed trees but otherwise untouched.

I was in Clinton Hill during Sandy, too. Kitty corner from Kum Kau.

I live pretty much across from the Benjamin Banneker academy. And i was so unscathed during Sandy that I was basically liveblogging in one of the threads in here during the storm. Literally the only thing that happened is that I think a power surge at one point shorted out my wireless router, and so that $45 for a new one was my only post-storm expense.

meanwhile three of the people I knew from my old kayak group in Red Hook were flooded out and the storm surge picked up our boathouse (an old shipping container filled with boats) and moved it 20 feet down the street from where it had been sitting.
posted by EmpressCallipygos at 12:34 PM on January 9, 2018 [1 favorite]

i was so unscathed during Sandy that I was basically liveblogging in one of the threads in here during the storm.

Yup. We had a "Dark 'n' Stormy" party where we, well, drank Dark 'n' Stormys. At one point a wind gust blew some insulation out of a window frame, but that was it. Hearing about and witnessing the devastation that occurred elsewhere gave me a really horrible cause of the guilts for months.
posted by grumpybear69 at 12:37 PM on January 9, 2018

After reading the futuristic novel The Country of Ice Cream Star, in which a visit to the 4th floor of the housing projects across the street from me has to be made via boat, I began to worry about my watery future. I contacted https://www.floodhelpny.org/ and got my free flood audit. They measure the elevation of your property and use both the old and proposed new flood maps to determine insurance rates.
posted by Obscure Reference at 12:43 PM on January 9, 2018

I left out the best part--the insurance agent who will handle my case is named: Tom Flood.
posted by Obscure Reference at 12:45 PM on January 9, 2018 [7 favorites]

I'm really sad for the people in Canarsie who were profiled who who have mortgages but just can't afford the extra $50-$80 bucks a month that flood insurance would cost them. There have been plenty of questions on the green about affordability of getting X or Y house, and the advice is usually solid. If you can't put away anything for house expenses, or housing emergencies you can't really afford the mortgage.

I assume this is a more wide-spread issue in places like New York or San Francisco where house prices are astronomical, but it makes me curious. If these people can't afford to buy flood insurance now, when it's as low as it's ever going to get, how can they afford to rebuild their lives after another flood when all their stuff gets destroyed? The gov't doesn't hand out that much money to disaster victims. What do they do when a pipe busts, or their 20-year old roof needs to be replaced? I'm not trying to be judgey, but honestly curious. Owning a home has been the most expensive undertaking of my life so far, attempting to do so with zero margin for error would leave me an anxiety-ridden mess every day.

There's no good answers here, climate change is going to screw over a ton of coastal dwellers hard, but keeping the new flood maps mired in "negotiations" for years certainly isn't going to be part of the solution.
posted by sharp pointy objects at 1:13 PM on January 9, 2018 [3 favorites]

1 in 100 floodplains are also immensely conservative--even before considering climate change, I think at last half, or maybe it was 40% of NFIP claims from from outside the 1 in 100 zone where insurance is mandatory.

1 in 500 floodplain should trigger mandatory flood insurance; actually, with climate change 1 in 1000 year floodplain is starting to get flooded every year, at least on a regional basis in the Gulf of Mexico states. So, 1 in 1000 is more like the new 1 in 100. we're also in a wet cycle on the Gulf Coast....

But people who flood every year are still not required to buy flood insurance, because none of the new risks from climate are incorporated into the evaluation of what "1 in 100" risk means.

(oh you can forget about changing the maps just for new development. FEMA can't change the maps fast enough to keep up with disasters, they aren't going to keep up with development. If you live in a rich county, consider pushing the county to update their drainage planning. Some county officials are small enough to avoid being purchased by real estate interests.)

basically, more people in the nation have to pay into the program, many many more, need to pay into the program for it to work. It's like healthcare, but on a much larger scale, transmogrified by the fact that Alan Greenspan warped the US economy so that it's pegged to flood prone real estate.

I've seen progressive engineers call for evaluating the flood risk up to the 1 in 10000 year floodplain, or a total evaluation of risk for all points--- just to make it clear that being outside of 1 in 100 is not an absolution of flood risk.

The residents have a right to know! The developers make more money, though, by keeping everyone ignorant.


Also, hazardous waste materials only have to be contained to withstand the 1 in 25 year flood event. So, the standards need to be raised tremendously for corporations. The government is just allowing them to spill everywhere with this double standard.
posted by eustatic at 1:19 PM on January 9, 2018 [5 favorites]

This happened to us on the other side of the country ... a year after we bought the place, FEMA updated the maps and put is in the highest risk zone. Flood Insurance became mandatory, and increasingly expensive as the government pulls back the subsidy. It was nearly $4k per year by the time we sold in 2015, and absolutely a factor in our decision.
posted by notyou at 1:20 PM on January 9, 2018

notyou, that is exactly how the program is supposed to work. The USA loves the free market.
posted by eustatic at 1:23 PM on January 9, 2018 [1 favorite]

The other thing is, why not sue Exxon, and the others responsible, rather than FEMA? killing the messenger will only get you so far.
posted by eustatic at 1:25 PM on January 9, 2018

Not on topic, but gosh, I wish we could mark when something is a direct link to the NYT, I’m tired of using up free articles without intending to, and dealing with endless paywalls for yet another month.
posted by kinnakeet at 1:52 PM on January 9, 2018 [2 favorites]

kinnakeet: "Not on topic, but gosh, I wish we could mark when something is a direct link to the NYT, I’m tired of using up free articles without intending to, and dealing with endless paywalls for yet another month."

Didn't I mark it? I intended SLNYT at least to mean "single-link New York Times."
posted by crazy with stars at 2:08 PM on January 9, 2018

llc: "Will there will be changes in levels and flows throughout the watershed ?[...] Will floods in the watershed be higher and last longer because the drainage outlet is in a state of permanent flood ?"

Yep, pretty much, with local bumps and channels within as well as above the soil; and building on a high water table is more difficult. Oakland Geology is thinking about sea-level rise and an inland lake today, and comments "as the sea rises, so will the groundwater in the dry land along the coast. Basements that are a few feet above the water table today will be permanent pools in 2100. Streets laid down on dry ground will find their roadbeds turning mushy, more prone to traffic damage. In that respect, rising sea levels will affect things much farther from shore than the tides reach."
posted by clew at 2:47 PM on January 9, 2018 [3 favorites]

What are the non-coastal effects on watersheds from sea level rise ?

Sewer plants are all gravity fed so they will fail.
posted by fshgrl at 3:13 PM on January 9, 2018 [2 favorites]

Fortunately, there are low-lying cities now working out non-gravity-flushed septic management systems. Big change for the heirs of Bazalgette, but at least there's an alternative.

I've been looking for a nice sketch of hydrodynamics, and it's just a huge topic, but this is a nice one for elevation and sediment.
posted by clew at 3:33 PM on January 9, 2018

John Oliver has a really good summary of flooding, zoning, insurance, etc. It was very eye opening. I highly recommend watching it.

After the government helped create affordable flood insurance in 1968: "But crucially, the aim at the time was not that people would be staying in at-risk homes permanently."

As the FEMA administrator states, "They presumed that if we told people they were at risk, they would move. They presumed that over the life of the program those discounts wouldn't need to be continued."

Eligibility for discounted flood insurance is determined by floodplain maps. Therefore if the maps are outdated, or the zones aren't enforced, people are displaced or bankrupt. If they are enforced, then there is still millions/billions of dollars in damages for housing/infrastructure that shouldn't have been built there.

When a flood storm hits, the insurers make money. So for them there isn't incentive to move out of those zones.

Of course, if they don't build there or move people out, then were will they go? In many of these places there are already housing crisis, but flooding is a major costly issue. What about these people whose primary home is in these zones? The people can't move if they can't sell their house, so they need a buyout or support. At some point, many of these places will be literally unlivable.
posted by Crystalinne at 3:40 PM on January 9, 2018 [1 favorite]

What are the non-coastal effects on watersheds from sea level rise ?

To pick just one example, salt water infiltration into aquifers will increase, impacting drinking water for a lot of people inland. But more than just sea level rise, climate change means changes to the hydrograph (so maybe you get less snow and more rain, which means that water runs off quickly rather than being stored as snow) which often mean that peak floods will increase. So the impacts will be complex, beneficial to some areas but devastating in others, with the rise in sea levels intertwined.

Will floods in the watershed be higher and last longer because the drainage outlet is in a state of permanent flood ?

Tides can back up rivers a surprisingly long distance, so in some systems those effects may be felt a long way inland. We've leveed and channelized most estuaries and river deltas, so the systems will be less able to respond and adapt, likely pushing impacts further inland.

Personally, my preference would be for the flood control and regulations to be centered on the science, but obviously property is political first and foremost, so we are stuck with some pretty crappy tradeoffs.
posted by Dip Flash at 5:37 PM on January 9, 2018 [2 favorites]

The residents have a right to know! The developers make more money, though, by keeping everyone ignorant.

Meanwhile, almost 500 feet above sea level, in Dayton, Kentucky, right across the incredibly flood-prone Ohio River from Cincinnati, you can — if you happen to be a complete fucking idiot — buy a brand new million-dollar riverside McMansion outside the levee that has been the only thing keeping the entire town from flooding several times over since its construction in 1981, which previously happened on a fairly regular basis. Oh, and your million-dollar home will be less than three feet from the neighboring ones, because that way the developer can get as much quick cash from as little land as possible before the water rises.

As long as developers are allowed to exploit people’s unbelievable stupidity by uttering the magic words “scenic waterfront property,” they will. Floodplains are called floodplains for a reason. Governments, get governing.
posted by Sys Rq at 5:37 PM on January 9, 2018 [4 favorites]

>I admit that I'm baffled as to why the city contested what looked like a more expansive flood-zone map right after Sandy. I've read the article, but still don't understand why they'd do that; what am I missing?

>The impact on property values in the new flood zone, I'd imagine.

Falling property values can also affect the tax base. The more flood-prone towns and cities with falling property values could have a diminishing tax base to pay for increasingly expensive mitigation. They will also not be able to issue high grade bonds, partly because their property base and infrastructure will be increasingly worthless.

What are the non-coastal effects on watersheds from sea level rise ?
Rising water tables, and brown field sites, on tidal rivers, is a concern. A big chunk of the industrial revolution in the US took place on tidal rivers, because of transportation. Imagine a 5 to 10 ft sea level rise* - and higher tides, and then more powerful storm surges from more powerful storm systems - and toxic crap leaching from the sites of old rail yards, oil refineries, stockyards, power stations, etc.

*There are increasing concerns regarding catastrophic ice sheet collapses triggering rises in this range.
posted by carter at 10:56 PM on January 9, 2018 [3 favorites]