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This article in SSSAJ

  1. Vol. 59 No. 4, p. 982-990
    Received: Apr 8, 1994

    * Corresponding author(s): chihua@ecn.purdue.edu
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Empirical Analysis of Slope and Runoff For Sediment Delivery from Interrill Areas

  1. Chi-hua Huang 
  1. National Soil Erosion Research Lab., 1196 SOIL Bldg., Purdue Univ., West Lafayette, IN 47907-1196



Slope steepness (S) and runoff discharge (qw) are two major factors in determining sediment delivery rates (qs) from interrill areas. Under the current interrill erosion model concept, these two factors are assumed to have independent effects on qs; thus, each factor can be quantified individually if the other factor is kept constant. This study was conducted to show the effects of S and qw on qs and their interdependency. Sediment discharge rates, measured under different rainfall intensities and slope gradients, for eight soils from two laboratory studies were analyzed empirically with curve-fitting procedures. Results showed that there was a pair of empirical equations for each soil: qs = A1 q2w + A2 qw + A3 and qs = B1 S2 + B2 S + B3, where A1, A2, and A3 are functions of S and B1, B2, and B3 are functions of qw. In other words, effects of slope steepness and runoff on sediment delivery are dependent on each other. When S and qw were combined together as stream power, Ω, and plotted against sediment concentration, qs/qw, a unique nonlinear relationship existed for each soil: qs/qq = D1Ω2 + D2Ω + D3, where D1, D2, and D3 are soil-dependent coefficients. The stream power, which encompasses both slope and runoff effects, may provide improved estimates for interrill erosion. Although not based on theory, this result may be useful in process-based erosion models.

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