2011 NeFSMA Conference - HAZUS Dam Breach Inundation Analyses

Application of HAZUS in Risk Management and Production of Updated Dam Breach Inundation Analyses - Paul Woodward and Carrie Romero, Olsson Associates

The objectives of this presentation are to educate the audience on ways to enhance Hazard Mitigation Plans during their required 5-yr update period. Key subjects presented will include the application of HAZUS in Risk Assessment and the production of updated dam breach inundation analyses.

Because the Papio-Missouri River NRD’s Hazard Mitigation Plan was the first plan adopted inthe State of Nebraska in 2006, it is the first plan to be officially updated before the mandatory 5-year deadline. However, as this presentation will emphasize, the 5-year update really isn’t a requirement, it is an opportunity to expand the possibilities of what can be achieved through hazard mitigation on multiple levels. First, FEMA and the Nebraska Emergency Management Agency are striving to get more entities involved, including schools and non-profits. Second, the range of hazards and the variety of potential actions is growing to meet the demands of thesenew agencies and to better accommodate beneficial projects.

The focus of our presentation will be to highlight the differences between the 2006 and the 2011P-MRNRD Hazard Mitigation Plan. One major difference between the two plans is the methodology used for overall risk assessment. While the original plan presented extensive historic evidence for potential hazards, the new plan utilizes FEMA’s Multi-Hazard Loss Estimation Software, HAZUS-MH. Using CENSUS and enhanced data available from local GIS sources, HAZUS-MH was able to provide damage estimates for earthquakes, floods, dam and levee failures.

One example of improved data was new analysis or redelineation for over 20 high hazard dams in the P-MRNRD. Where LiDAR and property parcel data was available, dam breach inundation maps were updated to accurately show the limits of impact and to produce a database of affected property owners should they need to be contacted during an emergency. In fact, these updated maps are not only used in the Hazard Mitigation Plan, but have been updated in Local Emergency Operations Plans for each dam and have been put to use in some local desktop exercises.

The last key difference between the original plan and the updated plan is the mitigation goals and the opportunities for using better risk assessment data to support a wide range of mitigation projects. Example mitigation actions, programs or projects include storm shelters, flood and tornado warning systems, drainage and channel improvements, property buyouts, revised flood hazard maps, backup generators, burying power lines, encourage proper tree maintenance, stormwater management, and many others.

Mississippi River Tests the Old River Control Structure - Historical Comparison

How much energy do you imagine is behind Mississippi River flows of 2 million cubic feet per second - sustained for three months?  The Army Corps of Engineers is confident that it is not enough to bring down the Old River Control Structure currently preventing the River from charting a new course down the Atchafalaya River valley (which, by the way, the Mississippi would prefer to do!).  Let's hope they are correct as more than just a river diversion structure is at risk if it does not.  I encourage you to take just a couple minutes to pour over this articulate summary from Weather Underground http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1801.

The graphics, history, and description of possible impacts are eye popping.  The graph in the article displayed the (now previous) 1973 record flood event by comparison and is a snapshot taken May 13, 2011.  The most current version will be found at the following link for you to observe http://www.mvn.usace.army.mil/eng/edhd/lat.gif.  At the time of this post, the 1973 event had just been exceeded and was still climbing rapidly.

Source: US Army Corps of Engineers



Flooding Mississippi River - Blowing Up Levees and Returning Floodplains

This morning, the Mississippi River crested in Memphis, rising just shy of the all-time record height of 48.7 feet set during the great 1937 flood. The river, normally half a mile wide at Memphis, is now about three miles wide.  The only reason that this flood didn't set a new record was because the Army Corps of Engineers blasted levees and opened up two "floodways."  Find full articles via GOOD Magazine

Should We Follow the Dutch and Give Land Back to the Flooding Mississippi River?

The Project Flood Is Upon Us": Mississippi River Surge Is a 1-in-500 Year Event

The promotional video for "Room for the River" (english) or "ruimte voor de rivier" (dutch) is worth 3.5 minutes of your time just to see how social marketing for flood-related topics occurs in other parts of the world.  And if you want to see video of the levee being taken down for the Project Flood article from Wall Street Journal "Great Balls of Fire" News Hub.

FPF - Changes to FEMA's "Without Levee" Policy

Last week the Washington Post reported that FEMA Administrator Craig Fugate stated in a letter to 27 senators that FEMA would be doing a more detailed analysis of the flood risk in area with levees.  Click here to read the article.

The letter from Administrator Fugate came as a response to a letter sent by 27 senators (including Nebraska Senator Mike Johanns) regarding concerns about communities with provisionally accredited or non-federal accredited levees. 

FEMA's current policy is to map the areas behind the levees with a special designation of "without levee" and put areas in the floodplain.  Several communities in Nebraska are affected by this policy.

At this time, it is unclear how this will affect communities with provisionally accredited or un-accredited levees.  NeFSMA will continue to follow this story and provide you with updates.