ABSTRACT:
The pattern of ephemeral gully erosion and associated soil properties were investigated in three southeastern Minnesota soilscapes during 1988 and 1989. The associations between topgraphic attributes and erosion characteristics of sample sites were also examined. No ephemeral erosion was measured after the investigation began in the drought year of 1988. In 1989 soil lost from ephemeral gullies ranged from 0.8 to 1.6 Mg/ba (.4 to .7 ton/ac) at the study sites, or one-tenth of that reported in the literature for similar watersheds. Pre-1988 data available at one site showed that soil voidage was an order of magnitude greater during the wetterthannormal 1986 season. A simple erosion model predicting topsoil removal and subsoil mixing in upper reaches and deposition in lower ephemeral gully reaches, does not accurately describe erosion processes in these Landscapes. Impact of ephemeral erosion on soil properties in landscapes varied depending on relative 1) rill and interrill contributions, 2) proclivity for channel drifting, and 3) occurrence of depositional sorting in channels. Topographically sensitive controls of ephemeral erosion, such as surface saturation and stream transport capacity, played different roles in channel formation at each site. Topographic indices most useful for predicting ephemeral erosion were platform curvature, profile curvature•slope, Ln (unit area/slope), unit area•slope, and plan form curvature up-stream contributing area•aslope.
Footnotes
R.D. Lentz is with the USDA ARS in Kimberly, ID 83341; R.H. Dowdy is with USDA-ARS, University of Minnesota, St. Paul 55108; and R.H. Rust is in the Soil Science Department at the University of Minnesota, St. Paul 55108. The authors thank Dr. Ian Moore for assistance in computing site DTMs and Richard Baird and the SCS for providing pre-1988 data on ephemeral gully formation at the Mower site.
- Copyright 1993 by the Soil and Water Conservation Society
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