The Joseph R. Brown Heritage Society is sponsoring a presentation by Dr. Carrie Jennings entitled “A Slippery Slope: Towards Better Understanding and Prediction of At-Risk Hillsides.” Carrie is a geologist with the Minnesota Department of Natural Resources.
Minnesota’s wettest recorded month in June 2014 led to widespread landslides of sediment and rock in the metropolitan area and portions of south central Minnesota. The slope failures were primarily located along the Mississippi and Minnesota River corridors.
Dr. Jennings team inventoried historical slope failures in a broad region adjacent to major river corridors by searching online sources and print newspaper archives. Minnesota Department of Transportation personnel assisted in identifying problematic areas in heavily engineered landscapes near roadways. Failures were mapped using LiDAR data and digital elevation models. Failure scars discovered in this map-making process were noted and municipalities contacted for more information on timing. The antecedent precipitation for two to four weeks prior to the failure and soil moisture conditions at the time of failure were extracted from climate archives for the periods identified. Nearly all of the slides occurred between May and October with peaks in June and August, both periods of higher incidence of convective storms in Minnesota. The earliest record of failure was in 1879. Wet periods in the late 1890s, early 1900s, 1980s and 1990s are reflected in an increase in reporting of slides. The increase in slides reported since 2010 may reflect the wetter climate as well as the ease of searching online records.
The goal of this work is to develop a better predictive model of when and where failures occur in order to inform hazard response plans, best management practices and to develop model ordinance language.
Please join us on April 6, 2016 at 7:00 PM at the Minnesota New County School, Main Street in Henderson, MN for this interesting and important topic.