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This article in SSSAJ

  1. Vol. 59 No. 1, p. 211-218
     
    Received: Oct 12, 1993
    Published: Jan, 1995


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doi:10.2136/sssaj1995.03615995005900010032x

Simulated Small-Channel Bed Scour and Head Cut Erosion Rates Compared

  1. J. C. Zhu ,
  2. C. J. Gantzer,
  3. S. H. Anderson,
  4. R. L. Peyton and
  5. E. E. Alberts
  1. Dep. of Soil and Atmospheric Sciences
    Dep. of Civil Engineering, Univ. of Missouri, Columbia, MO 65211
    USDA-ARS Cropping Systems and Water Quality Research Unit, Columbia, MO 65211

Abstract

Abstract

Concentrated-flow erosion is often a major part of cropland erosion. The concentrated-flow processes of bed scour and head cut need improved characterization to better predict and prevent erosion. This study was conducted to compare the erosion rates due to simulated small-scale bed-scour (Db) and head-cut (Dh) processes. A 6.4-m-long by 0.15-m-wide hydraulic flume was used to simulate concentrated-flow erosion on five Midwestern soils: Barnes (fine-loamy, mixed Udic Haploboroll), Forman (fine-loamy, mixed Udic Argiboroll), Mexico (fine, montmorillonitic, mesic Udollic Ochraqualf), Sharpsburg (fine, montmorillonitic, mesic Typic Argiudoll), and Sverdrup (sandy, mixed Udic Haploboroll). For slopes of 1.5, 3.5, and 5.0%, flow rates of 3.78, 5.67, 7.65, 11.34, and 15.12 L min−1 were used to provide a range from low (0.5 Pa) to moderate (2.5 Pa) shear stresses (τ). Soil detachment rates are functions of slope, flow rate, and shear stress. Slope, flow, their squares, and the slope × flow interaction were highly significant predictors of Db. Only flow, its square, and its interaction with slope were significant predictors of Db. Nonlinear power regressions using τ as an independent variable were better predictors of detachment than simple linear regressions. Erodibility for the soils from this study does not relate well with soil erodibility calculated using the Universal Soil Loss Equation. Differences in the slope and intercept of detachment vs. τ exist among soils. The value of Db was at least four times greater than Db for all soils at equal slope and flow rate, indicating that head cutting is the main process of detachment for the conditions tested.

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