A LANDSLIDE INVENTORY FOR MINNESOTA

Despite relatively low topographic relief, the post-glacial landscapes of Minnesota experience mass wasting that has caused damage to infrastructure and caused loss of life. Furthermore, research indicates that the majority of sediment delivered to streams in many watersheds comes from bluff erosion and landslides. We present a draft regional landslide inventory map for five watershed-scale landslide-prone regions in the Minnesota, Mississippi, Lake Superior, and Red River drainage basins. This is the first step in filling knowledge gaps regarding the distribution, failure mechanisms, frequency and future susceptibility of landslides in Minnesota. A multi-institution research team covering the most landslide prone regions of the state mapped over 7,000 distinct slides, most of which are in unconsolidated glacial sediment. These included deep and shallow seated translational and rotational slides, earthflows, rock fall, and other forms of slope failure. These were documented from historical archives and determined remotely from air photos, lidar, and lidar-derivative layers including red relief (a combination of slope and topographic openness), hillshade, slope, aspect, and curvature. A significant portion of the remotely mapped slides were field-checked to ensure accuracy. Slides were mapped using a geodatabase schema modified from existing protocols used by the states of Oregon and Washington and Hennepin County, Minnesota. This inventory is one part of an ongoing effort to generate better understanding of landslide susceptibility across Minnesota. Analysis of the controlling factors of landslide occurrence (slope, lithology, proximity to streams, etc.), combined with analysis of landscape response to events such as the 2012 Duluth area precipitation event from repeat lidar, will be used to generalize research findings into a landslide susceptibility map for the state.

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Committee on Minnesota Resources (LCCMR).