Toolbox: Floods, Prevention, Response, Recovery

Spring [2011] has barely begun, and already New Jersey residents have slogged through massive multi-round floods, cities from Cincinnati to Atlanta are nervously waiting to see what winter rainfall will bring, and Congress is again trying to decide what to do about the National Flood Insurance Program, which is drowning in debt.

Proving that when it rains, it pours, the National Weather Service recently released its National Hydrologic Assessment, which forecasts major spring flooding from Fargo to St. Louis, including extremely elevated risk in places like St. Paul, Minnesota and water-weary Sioux Falls, South Dakota, which suffered a massive flood just last year.

Add to all of this the fact that the National Oceanic and Atmospheric Administration dubbed March 14-18, Flood Safety Awareness Week, and it's a safe bet that flood stories are a hot news item for much of the country.

If you find yourself on assignment covering stories of water overrunning its natural boundaries, here are some sources of information that will help you ... get your feet wet.


According to the Federal Emergency Management Agency (FEMA), floods are the most common natural disaster in the United States. Floods have caused $24 billion in damage over the last ten years. "High risk" areas for floods have a 1% chance of flooding any given year and a 26% chance of flooding during the life of a 30-year mortgage. However, that doesn't necessarily translate into smooth sailing for homes outside these areas. Nearly 25% of all flood-damage insurance claims come from homes that are in what FEMA designates "low to moderate risk areas."

FEMA's "Flood Hazard" webpage and the National Flood Insurance Program's "Media Resources"  site are good places to start for information on flood frequency, planning and insurance issues and other relevant material.

To get a sense of just where your community stands in regards to flood risk, FEMA offers online Flood Insurance Rate Maps (FIRMs). The database is searchable by state, county and city/township and will tell you if you're in a low, average or high risk zone.


Since flooding is such a major problem, a lot of time, money and effort have gone in to forecasting when the water will wreak havoc.

According to NOAA, flood predictions rely on integrating numerous variables, like "snowpack, soil moisture, temperature, climate and long range weather prediction."

It is possible to look at single factors in flood risk, as NOAA produces online maps on variables like daily rainfall accumulation and current river and lake levels in the "Floods Monitor" section of their website. They also offer analysis of the current snowpack around the country, as well as produce the "National Water Resources Outlook," important to flood risk assessment, since areas with higher current water resources are more likely to have the saturated soils that shed water and exacerbate flooding situations.

For a more synthesized version of all of the above, NOAA and the National Weather Service offer weekly "Significant River Flood Outlook" maps. The current map was released March 29 and is valid until April 15.

These are all elements of what NOAA calls its "Advanced Hydrologic Prediction Service." For a map of river forecast centers that contribute to this report, go here.

The United States Geological Survey has an online resource called "WaterWatch," which offers maps on drought, flood, current streamflow and past flow/runoff. It is an important tool in any toolkit as it allows users to request data from specific past dates or over a range of time.

The most visually stunning resource is the USGS's "current streamflow map." The map shows the current day's streamflow compared to the historical streamflow of that day in any area of the United States. It also allows users to overlay Google map and Google earth applications on top of the streamflow map for truly descriptive graphics.


Of course the story of a flood isn't over once the waters recede. First, someone has to estimate the damage. The National Weather Service has compiled yearly damage estimates, available here, but those numbers are, admittedly, only estimates. A NOAA-funded study under auspices of the NationalCenter for Atmospheric Research, "Flood Damage in the United States, 1926-2003," offers a "reanalysis" of NWS estimates.

To get more current information of either floods-in-progress, or recent floods, try contacting your state office of emergency management. Here is a list of state offices and agencies of emergency management. Besides property loss and the immediate human safety threat of rising waters, floods produce an assortment of human health concerns, from elevated bacteria levels flushed from municipal sewer systems, to mold growing in a damp recently flooded basement, to hypothermia from standing water and a condition called trench foot, the CDC reports a number of post-flood concerns.

The CDC offers advice on how to be as prepared as possible for rising waters and how to protect your health when you return home after a flood.

UPDATE November 1, 2012: For stormwater resources, see Sandy Stormwater Hits U.S. With Pollution Mess.

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