Colorado flooding

For four years back in the early 1970s, Lynda and I lived in Boulder, Colorado.  It's been a while since we've been back, but i can still sort of recall the little stream that came down out of Boulder Canyon.  So the videos and pictures of the recent flooding are that much more remarkable, if not incredible.  The New York Times reports that 4,000 people in Boulder Canyon were told to evacuate immediately; and another 4,000 were told to move to higher floors.  The main campus of the University of Colorado has been closed.  Early estimates report that 20 percent of the university's buildings have had some amount of water damage, including the theater and main library.  There have been three reported deaths so far and more flood damage in and around canyons all along the Colorado front range.  The state's governor, John Hickenlooper, has referred to it as among the worst flooding in the state's history.

How could that much water collect and roar down the canyon and cause all that damage?  The Times reports 15 inches of rainfall in the past few days.  And where the rain fell on hillsides above Boulder and other canyons that had been burned by recent forest fires, there was nothing to absorb it.  Worse, heat from the fires had created a layer of soil that is virtually waterproof.  The rain falls and virtually all of it immediately heads downhill, collecting dirt, rocks, and all sorts of debris as it goes.  It knocks down and sweeps along almost everything in its path and doesn't stop until it looses energy on the plains beyond the mouths of the canyons.

After people recover as best they can from the shock, and after the cleanup, I hope the papers will continue to cover how, if at all, Boulder and the other communities respond.  It's a version of the situation following almost any weather-related disaster.  It's on-going in New York and New Jersey in the aftermath of Hurricane Sandy.  Is this combination of bare hillsides after forest fires and heavy rains an extraordinary, highly unlikely ever-to-be-repeated event?  Or does climate change make such extreme weather, even without the forest fires, more likely?  Is there a need to take steps to mitigate damage from similar floods in the future?  Would this influence land use decisions in the canyons?

Building up protections

Give New York credit for its efforts to learn from last year's Hurricane Sandy.  Less a year after the storm that causing more than $19 billion in damage, New York City, following the State, has now announced proposals aimed at reducing risks of similar damage in future storms. 
 
Last Tuesday, NYC mayor, Michael Bloomberg, described plans to protect vulnerable buildings along the city's 520-mile floodplain.  The proposals including modifying new and existing buildings to reinforce foundations, as well as raise the levels of critical equipment.  They also include proposals to build a system of flood walls, levees, and bulkheads at critical points around the city.  The total cost is estimated at $20 billion, although most expect it to go higher as measures would be implemented.

As I noted the other day, New York City currently has nearly 400,000 people living and working within its 100-year flood plain (which these days are often more like 50-year flood plains).  Generally, the mayor's proposals are aimed at protecting those residents, and in addition, allowing for that number to double over the next 30 years or so.

What's more, the proposals include one seemingly head-scratching idea to use new residential and office development as a means of protecting against storm surge.  The report describes a project the mayor referred to as Seaport City, a complex of apartments and office buildings to be built on landfill extending out from the shoreline below the Brooklyn Bridge.  Quite possibly I'm missing something, but it seems that, while the new development might protect existing territory along that part of the East Side, the new developments would themselves become the at-risk, exposed buildings. 

I know New York City is very different from coastal areas on Long Island where Governor Cuomo has proposed paying landowners to give up their houses and permit the coast to return to something like a natural protective system of dunes and marshes.  I suspect that there's little, if any, of the New York City floodplain where anything similar would be possible.  Still, as one researcher observed, you "can't guarantee protection for infrastructure that is in vulnerable locations."  Yet Mayor Bloomberg's proposals seem prepared to try. 

I'm hoping an interesting debate will follow since there's a lot I need to learn.

Waterfront property

What is it about living near water that's so attractive?  In the past it was easier to understand.  Waterways were sources of power for milling and early manufacture.  And oceans and rivers were transportation routes.  People lived near water probably without thinking too much about it.  They were simply living close to their work.  But why now when we have so many alternatives to water power and water-based transportation?  Nearly everywhere it seems developers push to offer more waterfront residences, local governments anxious about tax revenues approve them, and and people buy them, both as first and second homes.

And then come hurricanes and floods.  But somehow these disasters seem to have little effect on the waterfront development machine.  These thoughts come from reading a couple of recent New York Times articles.  One, on high water levels and flooding along the Danube in Austria and Hungary, noted that part of the reason for record high water levels was the reduced ability of river flood plains to absorb it. 

A Budapest neighborhood,  June 9, 2013. © Reuters/Laszlo Balogh

It cited a study from the Hungarian national water authority reporting that "the decreased drainage capacity of the Hungarian flood protection system was due largely to increased building on former floodplains along rivers."

The other was an article today on new warnings of risks posed to New york City from climate change, especially rising sea levels.  The City report noted that already some 398,000 people live within the 100-year flood plain.  But, rather than seeing that number reduced, the report expects it will more than double over the next 35 years or so.  It seems that mermaids' fatal siren songs are now sung by real estate developers.

"When the levee breaks, mama, you got to move" (Led Zeppelin)

How many marvelous pictures are there of the Loire River, often as a calm backdrop to towns and chateaux along the banks.  I've taken some myself, although I'd say their quality has mostly to do with the memories they bring back.

However calm the river may appear, recent floods in northeastern France along the Seine and Aube rivers must have reminded people living nearby that the Loire can do the same.  And a recent report from a regional public agency would have reinforced that reminder.  The report, from the Center Region's Direction régionale de l'environnement, de l'aménagement et du logement (DREAL) dealt with the condition of levees (example below) along the Loire and the risks in the event of 100-year flood conditions.  La Nouvelle République (Tours) reports that it's unlikely such a flood would overflow the tops of levees up stream from Tours.  But, it reported, various forces, natural and man-made, may have weakened the earthen barriers in certain places, creating risk of a breach.  

The probability of such a failure may be relatively low, but the consequences would be catastrophic; reportedly more than 100,000 people would need to be evacuated from areas around Tours (about 300,000 in the metropolitan area).  The point of the report was, in part, to remind local officials of the need for emergency evacuation plans, but also to reassure them that levee repair work was on-going.  

In contrast, nothing was said, at least in this forum, about what might be done to reduce the need for evacuations by limiting development in flood-prone areas.  Perhaps that's for another day.

Flood insurance premiums and coastal rebuilding

The consequences of Hurricane Sandy continue to play out along coastal areas where people are deciding what to do about damaged homes.  The New York Times had an article the other day about households thinking about rebuilding, but faced with suddenly much more expensive flood insurance.

© Rosanne Salvatore and Kathryn Kattalia/New York Daily News

Properties in areas classified as at risk for "severe and repeated" flooding will pay new, higher insurance premiums starting October 1 of this year, with 25 percent increases each year until rates reflect the actual cost of providing the insurance.  Owners can reduce these rates by raising their homes by several feet, or by moving out of the riskiest areas.  In either case these measures are likely to be expensive and many are reluctant to take them.  Some property owners have started to organize to oppose the higher rates.

Focused as it is on the financial strains of individual homeowners, the NYT article tends to be sympathetic.  But how much sympathy do they deserve?  The Times article does mention that many people with properties in at-risk areas have been paying subsidized rates.  And a 2011 report from the Center for Public Integrity notes that, nation-wide, property owners in flood-prone areas are paying only about 45 percent of the full-risk price.  One effect of this has been that the National Flood Insurance Program is badly under-funded and several times has had to borrow from the U.S. Treasury to meet insurance obligations.
 
I recognize that people along the New york and New Jersey shores face difficult decisions.  But even so it has to be asked whether there is any public policy reason to use federal resources to subsidize people so that they can continue to live in these high-risk areas?

Red River flooding, again

The New York Times reported this week that Fargo and other towns along the Red River in North Dakota are again facing the likelihood of flooding.  This will be the fourth time in five years.  At the moment, it seems every available person has been mobilized to fill sandbags.  Understandably, people may be getting tired of this kind of emergency response and may be looking for less last-minute ways to avoid flood damage.

© Donald P. Schwert. Dept. of Geology, NDSU

Equally understandably, it seems they're giving most attention to familiar measures -- levees and spillways and diversionary channels.  The Times reports that 14 miles of levees have been built in Fargo in the last four years.  Plans are also well under way for a much bigger project.  This is a design for 35 miles of channels to divert flood waters away from the city.  Total cost, $1.8 billion.  A little over $300 million is supposed to come from North Dakota state and local sources; the rest -- about $1.2 billion -- would come from the federal government.

Fargo has purchased and cleared out a few houses located in the floodplain.  But the Times article doesn't mention any plans to make broader use of this tactic.  It doesn't appear, for example, that there's been any consideration given to applying the funds for levees and diversionary channels to buying up homes and businesses in floodplain areas.  Levees and channel systems will inevitably require maintenance.  An open floodplain, left as a park or nature preserve, doesn't. 

Admittedly, I suspect this approach of "sustainable floodplain management" may be more complicated in the Red River Valley.  Apparently this part of North Dakota and northern Minnesota in the U.S., and Manitoba and Saskatchewan in Canada, was an immense inland glacial lake as recently as about 10,000 years ago.  Today, the Red River descends very gradually across this old lake bed on its way north to Lake Winnipeg.  Because of this geology and history, the river has etched very little in the way of a valley.  This means that when waters rise they spread out across a wide area, across a very wide floodplain.  It is also why an approach to floodplain management that would apply in other areas may be harder to apply here. 

Even so, when close to $2 billion is likely to be spent on engineered solutions to flooding -- solutions that will require additional money every year for maintenance -- it would seem reasonable to ask if there aren't less costly, more environmentally rational, alternatives.