The American Society of Civil Engineers (ASCE) estimates that 40% of Americans live or work near a levee. The average age of these levees are 55 years (some as old as 100 yrs) and they have worked to protect over $141 billion in flood damages–a 6:1 return on investment (24:1 on the Mississippi River and tributaries).
However, over the last 50-100 years, we have significantly developed floodplains lands, experienced sea level rise, and neglected the maintenance of these levees. ASCE gives the national levee infrastructure a D- grade (very poor). Grades are based on capacity, condition, funding, future needs, operation/maintenance, public safety, resilience (how well they withstand disasters), and innovation.
It’s not only levees that protect land from floods. And it’s not only levees that are aging nationally.
- Bridges: C+
- Dams: D
- Inland Waterways: D
- Levees: D-
- Roads: D (get flooded)
- Wastewater management: D (pipes, sewers, storm water drains, etc.)
Every facet of our storm water management system is dismally graded meaning that Americans all over are at risk from an aging, failing infrastructure. (See the full report card here)
This autumn has seen an historical amount of rain in the midwest as an unusually warm El Nino cycle takes charge of North American weather. Illinois and Missouri have logged about 10 inches of rain over three days causing the Mississippi, Missouri rivers and tributaries to flood. Officials down south are watching carefully as Mississippi flood water is scheduled to hit the brand new New Orleans levees in about a week (Jan. 9).
After Hurricane Katrina (2011), the US Army Corps of Engineers was authorized to spend about $14.6 billion to strengthen levee walls, build massive flood gates, install cool new flood modeling computers, and update the city’s water pumps (according to CNBC and NPR). But, as the Engineer Corps is wont to warn, new infrastructure doesn’t necessarily assure safety. New Orleans is a fishbowl. We can build lots of walls, but water will always need to go somewhere–a sentiment that Bob Criss Professor of geology at Washington University expresses in the Journal of Earth Science.
“The Mississippi River should not be going crazy after three days of rain,” Criss said in an interview. The problem, he believes, is that we’ve walled off rivers without thinking about a release for the water. It’s Downstream City’s problem. The Army Corps of Engineers has long agreed, stating that the Mississippi River and it’s tributaries (and–presumably–by extension all river systems) should be connected “more naturally” with the flood plains. This means undeveloping the flood plains.
The combination of failing infrastructure with poor long term flood management planning has caused experts from many fields to call the Federal government to reimagine national flood policy.
Current national policy is based on insurance policy statistics. You may have heard the term “100-year” or “500- year” flood or storm. A “100-year storm”is a storm of such a size that it’s chances of happening in any given year are 1%. Depending on who you ask, Hurricane Katrina was a 100-year storm. However,
The 100-year threshold is also a statistical guess based on data on past storms and assessments of whether they’ll occur in the future. That means the models change every time a new hurricane strikes. The numbers being used as guidelines for construction are changing as time passes.
And, as an engineer working on New Orleans levees points out, the current levees were meant to protect city infrastructure. Residents shouldn’t depend upon them to protect lives. There’s always the chance that a bigger storm will come along.
Thousands of miles away, Washington State–well known for it’s rain–is also struggling with flooding. Unusual amounts of snow in the Olympics combined with lots of rain caused flooding along the coast. Enough flooding to open the Emergency Operation’s Center which stymied this researcher’s thesis by causing the people she needed to be busy. (“Graduation postponed on account of rain,” she lamented on social media.) It’s not just the rain. In fact, 2015 was actually a drier than normal year. It’s that Washington coast is built for moderate, continual rains. Not for cycles of drenching rains and drought. The Washington State Climatology Office believes that this rain-drought cycling is a direct result of global warming and won’t get better. Just like how bigger storms are becoming more regular. Global warming is causing extremes of all sorts.
What can be done?
The ASCE has a “tell your legislator” form and ways to share the news on their report card website (scroll down). We need to pressure local and federal governments to make decisions based on new data and the long view. But even more importantly, as citizens, we need to accept taxes which pay for infrastructure. In New Orleans, the city is fighting with the feds over who will pay to maintain the new levees. Voters have twice declined to raise taxes to pay for it. One frustrated official exclaims,
“We’re talking about $5 a month to the average taxpayer. That’s a six-pack. That’s a pound of crawfish in April…This is a country that’s run by the citizens. The citizens decide they don’t want to have flood protection, then we’re not going to have flood protection.”
I am not advocating for blind acceptance of every new tax hike. Like responsible people, we need to watch where our money goes. We should buy things with our taxes that are “worth it”, that is: effective, efficient, and high quality. We also need to watch that our towns and cities use our taxes the way they promised.
That seems like a lot of work. But maybe it’s worth it for keeping your house dry and your water clean.
- News: The Guardian, Jan. 3, 2016
- NOAA El Nino Portal
- Interagency Flood Plain Report to Congress (1994)
- WA State Climatology Office Newsletter (check your state for one!)
- Levee basics
- Flood control basics
- Flood Plain Management, FEMA
- Levee Resource Library, FEMA
- National Levee Database, Army Corps of Engineers