INTEGRATING SOILS WITH LANDFORMS AT THE LANDSCAPE SCALE: EXAMPLES FROM MICHIGAN'S PHYSIOGRAPHIC MAP

Now that NRCS county-scale soil map coverages are largely completed and in digital form for the US, and 10-m (or better) DEMs also are available, opportunities exist to use these data in unique and profoundly geographic/geomorphic ways. Just as Pete Birkeland and his students made good use of similar data on soils and landforms in their research, using analog and/or paper maps, we present research done using digital maps. The work was done by a research team of students and faculty at Michigan State University, work that takes full advantage of these new digital data sets. Our purpose was to use spatial data – especially soils and topography - to facilitate a mapping project on the physiography of Michigan. Perhaps never before have so many detailed and unique data sets, especially with regard to soils, been combined for the purpose of creating a physiographic map. We developed and utilized soil parent material, soil surface and subsurface textures, soil drainage index, and parent material graveliness in this map. Also included in our data were coverages of elevation, surface roughness, water table depth, presettlement vegetation, land cover, bedrock geology, and drift thickness.

The mapping was subjective and iterative, taking advantage of class feedback on early versions of regional boundaries. We also examined most of our boundaries in the field, and altered several boundaries based on field observations. Clearly, the data products gleaned from NRCS SSURGO county-scale soil maps were a strength of the project. Most of our physiographic boundaries are, in large part, defined based on products derived from either 10-m raster elevation data or soils data, with other boundaries based on depth to bedrock, depth to the water table, or land use.

In this talk I present examples of different physiographic regions and their boundaries. My purpose is not to simply display the utility of the data and the quality of the mapping effort, but also to show how many of Pete Birkeland’s soil geomorphic concepts continue to hold today, at the landscape scale.