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Modeling Interrill Sediment Delivery
Author(s) -
Zhang X. C.,
Nearing M. A.,
Norton L. D.,
Miller W. P.,
West L. T.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200020021x
Subject(s) - surface runoff , hydrology (agriculture) , environmental science , infiltration (hvac) , soil water , sediment , loam , soil science , erosion , sediment transport , wepp , geology , geotechnical engineering , soil conservation , geomorphology , ecology , physics , biology , agriculture , thermodynamics
Shallow surface runoff is a primary transport agent for interrill sediment delivery. Runoff, rainfall intensity, and slope interactively affect interrill erosion. We hypothesized that the inclusion of a runoff factor in an interrill erosion model can reduce the dependence of the interrill soil erodibility ( K i ) on soil infiltration characteristics as well as improve model predictability. A complete factorial rainfall simulation experiment with two soils (Cecil sandy loam, a clayey, kaolinitic, thermic Typic Kanhapludult, and Dyke clay, a clayey, mixed, mesic Typic Rhodudult), four rainfall intensities, four slopes, and two replicates was conducted under prewetted conditions to measure runoff and sediment delivery rates. Tap water with electrical conductivity <0.2 dS m −1 was used in all the runs. Rainfall intensity I , unit discharge q , slope S , soil type, and their interactions significantly affected sediment delivery per unit area ( D i ). Sediment delivery had the greatest correlation ( r = 0.68) with unit discharge; however, neither discharge nor rainfall alone adequately predicted sediment delivery. The equation D i = K i Iq 1/2 S 2/3 was proposed. The linear intensity term ( I ) represents detachment of soil by raindrop impact and enhancement of transport capacity of sheet flow, while the product of q 1/2 S 2/3 describes sediment transport by sheet flow. Validation with independent data showed that the model predicted soil erodibilities well. The mean r 2 for four validation soils was 0.93 when the proposed model was fitted to validation data to predict interrill erodibility ( K i ). The better estimation of K i indicates that interrill erosion processes were adequately described by the model.