Are Ozark Streams Underfit? Using Gis to Re-Examine Dury's Theory of Underfit Streams

Abstract

The theory of underfit streams as described by George H. Dury has often been used to explain the distinct compound valleys found throughout the Ozark Plateaus physiographic province. Dury developed mathematical relationships between the valley meander wavelength and the stream meander wavelength to define the underfit condition. He found that Osage underfit streams fail to meander within the stream valley and have wavelength ratios of approximately 3.5, and that the valley meander wavelengths are 30 times the bankfull width of the stream. This study uses modern analytical techniques and data sets to test these mathematical relationships both for watersheds used in Dury's original study and for other watersheds in the region. Using GIS-based analysis of digital raster graphics, digital elevation models, and U.S. Geological Survey hydrology data, we could not replicate Dury's results. Most wavelength ratios measured for all streams were less than 3.0, and valley wavelengths ranged from 0.08 to 141 times the bankfull bed width of the river. The theory of underfit streams fails to explain the great variability of data derived in this analysis. In fact, this study suggests that structural controls have a greater influence on modern valley architecture than hydrologic controls.