We partnered with MnDOT to identify slope vulnerability along trunk highways in 44 counties. There were several phases to the project including the design and implementation of a Geographic Information Systems (GIS) slope stability model that assigned vulnerability factors to slopes within the right-of-way and adjacent areas. The model identified past slope failures, assigned risk factors, and statistically tested the geomorphic vulnerability factors that caused failures to predict future failures. Field assessments provided additional information that influenced final risk rankings. MnDOT will continue this project in a future phase of work to model the remaining counties.
The new Geographic Information Systems (GIS) slope failure model we created can be implemented anywhere in the state with minimal data input. It identifies landforms, geomorphic processes, and causative factors influencing slope failures in each part of the state. The model consists of three main components: 1.) identify past slope failures, 2.) model the causative factors of past slope failures and how they vary locally, and 3.) model the risk of new slope failures.
When tested, the model objectively identified risk of slope failure with the potential to affect state trunk highways; accounting for all 12 known types of slope failures. Vulnerability factors were tested to determine the most important causes of slope failures. The results validated the model’s capability of identifying risk in regions with different geology, geomorphology, and hydrology including the ravines and bluffs located along the Minnesota River Valley.
The results were ranked into four proposed risk management categories. The calculated risk incorporated the model outputs with existing infrastructure data including distance to roads and populated areas. The risk estimation process for this phase was considered preliminary; further consideration of risk tolerance and consequence definitions should be conducted.