Predicting Soil Loss and Runoff from Forest Roads and Seasonal Cropping Systems in Brazil Using WEPP

Abstract

used WEPP in Mato Grosso State and noted that simulated average annual sediment yield increased in one of the scenarios tested and decreased in the other two, reflecting the range of uncertainty in predictions of future rainfall. In another study in Mato Grosso State, Favis-Morlock and Guerra (2000) found that WEPP-CO 2 underestimated current-climate mean annual sediment yield. The model calculated a value of 6.86 t ha −1 y −1 , while the value measured during four years of monitoring was 12 t ha −1 y −1 .Martins Filho et al. (2003) validated the model to predict inter-rill erosion for three Oxisols. The initial proposed model for the dimensionless slope factor (S f ) did not provide a good relationship between the actual and predicted soil loss. The slope factor was better expressed using the equation S fa = 1.061 − 1.037 e −4 sinq , than by the equation S f = 1.050 − 0.850 e −4 sinq where q is the slope angle (degrees). The model D i = R I K i S fa predicts erosion well on the studied Oxisols where D i is the inter-rill soil loss (kg m −2 s −1 ), R is the rate of runoff (m s −1 ), I is the rainfall intensity (m s −1 ), K i is the inter-rill soil erodibility (kg s m −4 ) and S fa is the modified slope factor.Martins Filho et al. (2004) studied the covermanagement subfactor (C iII ) and concluded that the equations C iII = e −2.50 CS/100 and C iII = e −2.238 CS/100 allow good estimates for the cover-management subfactor, for slopes between 5.3% and 15.3%, where CS is the percentage ground cover on the soil surface. For slopes ∼36.3% the equation C iII = e −0.795 CS/100 is recommended. Nevertheless, the authors suggested that more research is needed to improve the calibration for steep slopes.Many of the dissertations and theses in Brazil using WEPP have been completed in Agricultural Engineering departments, reflecting the considerable concern over soil loss due to agricultural activities in Brazil. We have selected examples from two PhD theses (Garcia, 2001;Gonçalves, 2007) where the authors have applied WEPP in real situations and considered the associated limitations and potential. We describe in detail how the model was established and run, and the necessary data obtained for each application. Through their methodology and results, it is expected that WEPP users, in different parts of the world, will be able to use these two case studies as examples for subsequent model use, development and Handbook of Erosion ModellingEdited by R.P.C. Morgan and M.A. Nearing

Adapting the WEPP Hillslope Model and the TLS Technology to Predict Unpaved Road Soil Erosion

“…For example, Brown et al, (2013) simulated soil loss from forest roads with the WEPP model and evaluated the effect of management practices in reducing sediment delivery to streams [ 35 ]. Guerra and Silva (2011) adopted the WEPP model to predict sediment generation from 4 road segments [ 36 ]. In most of the above studies, the WEPP model was used to evaluate the total soil loss from road segments and then validated with field sediment yield data from sediment traps.…”

Adapting the WEPP hillslope model to predict unpaved road soil erosion in southern China

“…For example, Brown et al (2013) simulated soil loss from forest roads with the WEPP model and evaluated the effect of management practices in reducing sediment delivery to streams. Guerra and Silva (2011) adopted the WEPP model to predict sediment generation from 4 road segments. In most of the above studies, the WEPP model was used to evaluate the total soil loss from road segments and then validated with field sediment yield data from sediment traps.…”