Project Status Reports

PSR 2001- 01 October 2001

Predicting Flood Potential to Assist Reforestation for the Upper Mississippi River System

by Joseph H. Wlosinski and Laurie B. Wlosinski

Tree mortality along the Upper Mississippi River has been positively correlated with flood duration and amplitude. This mortality seems to be greatest in small trees. In fact, mortality of saplings was as high as 80% near St. Louis, Missouri, after flooding in 1993, with many areas experiencing 100% mortality of seedlings. In addition, numerous studies have shown that flood tolerance of trees is species specific. Thus, reforestation success at sites that have a high flood potential can be increased by planting taller seedlings or tree species that are more flood tolerant.

We developed flood potential models for the Upper Mississippi and lower Illinois Rivers to assist foresters in selecting sites, tree species, and tree sizes for successful reforestation. Model results are displayed as a series of tables, one for each river mile. Each table includes the percentage chance of flooding per year for a range of durations and elevations (feet above mean sea level). Percentage estimates were calculated for 3-day to 8-week periods and may include multiple flooding events within a single year. An example of a flood potential model for river mile 541 in Pool 13 is displayed in Table 1.

The model was based on daily water surface elevation data collected by the U.S. Army Corps of Engineers from 1954 through 1998 for the estimated growing season.  Estimated dates for the growing season were obtained from local foresters: April 30 to October 13 for Pools 2 through 10, April 15 to October 15 for Pools 11 through 22, and April 1 to November 1 for areas down river of Lock and Dam 22 and for the lower Illinois River. Water elevation gages that were missing more than 20 years worth of data were eliminated from analysis resulting in useful data from 133 gages (Table 2).  Other missing data for these gages were estimated. If a value was missing for only one day, it was estimated by interpolating between values from the day before and after at that gage. If values were missing for successive days, they were estimated with a second-order regression using data from a nearby gage. After the data sets were completed for the 133 gages, we used linear interpolation to estimate daily water elevations for river miles where no gage was present. Most gages are less than 20 miles apart with a maximum distance of 39 miles (Table 2). We then estimated the potential for flooding for each combination of river mile, elevation, and duration. Model results for the Upper Mississippi and lower Illinois Rivers are available to the public from the Upper Midwest Environmental Sciences Center's web site at http://www.umesc.usgs.gov/data_library/water_elevation/flood_potential.html. At the web site, tables are grouped for ease of access by pool or by 25-mile reach for the Open River (Table 2).

This report is a product of the Long Term Resource Monitoring Program for the Upper Mississippi River System. 

For further information, contact

USGS Upper Midwest Environmental
Sciences Center
2630 Fanta Reed Road
La Crosse, Wisconsin 54603

 
U.S. Fish and Wildlife Service
51 East Fourth Street
Winona, Minnesota 55987

Project Status Reports (PSRs) are preliminary documents whose purpose is to provide information on scientific activities. Because PSRs are only subject to internal peer review, they may not be cited. Use of trade names does not imply U.S. Government endorsement of commercial products. 

All Project Status Reports are accessible through the Upper Midwest Environmental Sciences Center's website at http://www.umesc.usgs.gov/reports_publications/psrs/umesc_psr.html