State Water Resources Research Institute Program

Project ID: 2012MN320B
Title: Predicting Erosional hotspots in North Shore streams from high-resolution spatial data
Project Type: Research
Start Date: 5/01/2012
End Date: 6/30/2013
Congressional District: MN 8
Focus Categories: Geomorphological Processes, Sediments, Surface Water
Keywords: North Shore, sediment, erosion, lidar, stream power
Principal Investigator: Gran, Karen Bobbitt
Federal Funds: $ 0
Non-Federal Matching Funds: $ 24,378
Abstract: Numerous streams along the North Shore of Lake Superior in Minnesota are listed as impaired for turbidity, prompting a need to understand sediment sources and erosional mechanisms within the basins. A great deal of effort has gone into developing detailed models and/or sediment budgets as part of the Total Maximum Daily Load (TMDL) process in rivers like the Knife and the Poplar. What we propose here is to construct a spatially-extensive erosion prediction model at the reach-scale for the entire North Shore based on new soon-to-be-released high-resolution aerial lidar and soils data. Although this model would not replace the highly detailed hydrologic models or sediment budgets required for management of impaired basins, it would provide a first pass look at where in the basin management efforts should focus while also providing information on where to implement watershed protection efforts in healthy watersheds.

North Shore streams generally flow through low-gradient till plains in their uplands before increasing in gradient and often incising into bedrock near the shore. Erosional hot spots exist where high gradients coincide with erodible substrates and where deeply-incised channels interact with erodible valley walls. These erosional hot spots may be exacerbated by changes in hydrology upstream. Our goal with this project is to develop a predictive erosional model by combining topographic data with soils and surficial geology in watersheds along the entire North Shore. Our project will take advantage of newly developed high-resolution lidar topographic data and high-resolution soils data to develop a more robust model than has previously been possible. Lidar data for northeastern Minnesota will be released over the winter and high-resolution soils data has been released for St. Louis county and will be released for the entire region by spring 2013. We propose a series of spatial analyses of topography combined with erodibility maps developed from soils data to develop erosion potential maps at the reach-scale. The erosion potential maps will be field-checked at the reach-scale during summer 2012. Data will then be summarized in terms of upstream erosion potential at a series of 39 sites with total suspended solids and turbidity data available to test how well high-resolution topographic and soils data aid in predicting water quality trends along the North Shore. Additional data including land use/land cover and upstream storage potential may be included for the watershed-scale assessment as these have been shown useful by other researchers in describing variations in hydrology and water quality data at the watershed-scale along the North Shore.

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