What Shall We Do About Floods?

This is the first in a series of op-eds that suggest what Congress should consider as it plans and funds the repair and modernization of America’s infrastructure.

 By William S. Becker

We are told that repairing and modernizing America’s infrastructure will be one topic on which there could be bipartisan cooperation in the next Congress, and between Congress and the White House.

Perhaps. Everyone agrees that the nation’s infrastructure needs work, in many cases urgently. But Congress will have to demonstrate an extraordinary level of bipartisanship to decide on the details. There are many tough and controversial issues to address.

One example is a type of infrastructure we don’t hear enough about compared, for example, to roads and bridges. There are about 84,000 dams in the United States built for recreation, flood control, irrigation, energy production and water storage.

While 38% of the nation’s dams were built for recreation, nearly 18% were built to control floods. The height of dam-building took place in the middle of the last century with structures designed to last about 50 years. Their average age today is 56.

Many have not been properly maintained. As of 2016 there were nearly 15,500 “high hazard” dams in the United States whose failure would cost lives. The American Society of Civil Engineers (ASCE) estimates it will cost $45 billion to repair them. Another organization, the Association of State Dam Safety Officials, puts the cost much higher at $64 billion. Every level of government in the United States owns dams; thousands more are privately owned.

One thing that engineers and policy makers did not anticipate a half-century ago is the amount of real estate development that would occur in natural floodplains when people assumed they were safe below dams. As a result, many flood control dams were built to protect farmlands, not lives.

They definitely were not built to hold back the extreme amounts of water we see from rainfall events today. The typical flood control dam was built to contain 100-year floods – floods with a 1% chance of occurring in any given year. But because of our changing climate, it is no longer unusual for communities to experience 500-year and 1,000-year floods, sometimes more than once within just a few years. As a result, to prevent a dam from failing completely, dam managers need to release large amounts of water that increase damages to farms and communities downriver.

Congress, the U.S. Army Corps of Engineers (USACE), state and local officials as well as private investors all will have to make some tough decisions. Will they try to repair and improve these dams? Given the uncertainties of climate change, to what standards should dams be built? How much more would super-dams cost? Should the people who live and work below old dams be required or given incentives to move elsewhere?

Dams are just part of the problem. Although there are no exact numbers on how many miles of levees are located in the United States, the National Committee on Levee Safety estimates they amount to as many as 35,000 miles. They are estimated to protect $1.3 trillion worth of property. They can be found in all states and in 22% of the nation’s counties, according to the USACE.

Nearly a fifth of America’s levees are rated as having high hazard potential. More than half  are owned by states and localities that have not made maintenance a high priority. Now, the ASCE says, some $80 billion is required to repair them.

There is another consideration. Some part, perhaps a significant part, of the nation’s vulnerability to flooding comes from the destruction of wetlands, forests and grasslands that once held rain where it fell. In some areas, the USACE has exacerbated flooding by straightening and channelizing the natural meanders in the course of rivers. Those twists and turns naturally slowed the speed of floodwaters. In places such as the Napa River Valley in California and the Kissimmee River in Florida, people have undertaken projects to put the meanders back.

Our cities are finding that flooding is more destructive because parking lots, streets and roofs shed water rather than absorbing it. Some cities are now using rooftop gardens and permeable surfaces to reduce this runoff.

What seems certain is that the flood control strategies, public policies and the type of structural investments the nation used in the last century may not be able to prevent flood disasters today. Congress will have to answer some pressing questions like these:

  • To what extent should government funding for flood control be used on non-structural methods rather than repairing dams and levees that lose flood protection value as storm intensities increase?
  • Why don’t flood insurance maps show dam failure zones so people who live and work below these structures can see their risk and be prepared to evacuate during threats of overtopping or structural failure?
  • If governments and investors choose to repair dams and levees or to build new ones, what engineering and design standards are necessary for the structures to withstand the rains and floods we should expect during the next half century or more of climate change?
  • Is there sufficient interaction between climate scientists, Congress, state and local officials, the USACE and FEMA to develop a science-based national strategy for preventing the loss of lives and property to floods?
  • Because climate scientists cannot tell us precisely what the levels of precipitation and flood dangers will be, what level of risk are governments, investors and citizens willing to take?
  • To what extent should governments get tough about discouraging real estate development in natural floodplains, or in the expanded floodplains being created by climate change, or in the areas that would be devastated if a dam or levee failed? Should governments encourage or require that existing buildings be removed from these high-risk areas?
  • What will drought and other impacts of climate change have on the capacity and locations of dams built to retain water for agricultural and urban use?
  • AmeriCorps operates a program called FEMA Corps, in which young people between 18 and 24 years old help communities with disaster preparedness, mitigation, response and recovery. Should governments provide FEMA Corps with resources for more young Americans to help communities restore the natural ecosystems that reduce flooding?

If and when Congress finally gets around to infrastructure investments in the United States, there will be a lot of competition for limited resources. If it prioritizes public investments based on risk, as it should, then reducing the danger of floods had better be very high on the list.

 

December 5th, 2018|home|