Open AccessEvaluating the WEPP Rangeland Hillslope Model Using Cesium‐137 Estimated Spatial Erosion Data
Author(s) -
Liu Bing,
Zhang Xunchang J.,
Storm Daniel E.,
Brown Glenn O.,
Cao Wenhong,
Duan Xingwu
Publication year - 2017
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2017.03.0067
Subject(s) - wepp , erosion , environmental science , hydrology (agriculture) , rangeland , soil science , surface runoff , rill , spatial variability , soil water , soil conservation , geology , geography , mathematics , geomorphology , agroforestry , ecology , geotechnical engineering , statistics , archaeology , biology , agriculture
Core Ideas WEPP rangeland model was evaluated using spatial erosion data for the first time. WEPP and 137 Cs methods predicted similar low soil erosion rates. Spatial erosion patterns predicted by WEPP and 137 Cs methods agreed well. WEPP predicted soil erosion patterns well along rangeland hillslopes. Lack of spatially distributed soil erosion data has greatly hampered the development and improvement of process‐based soil erosion models. The 137 Cs method has been widely used to estimate soil erosion and redistribution but has seldom been used to evaluate process‐based erosion models. This study evaluated spatial erosion patterns predicted by the Water Erosion Prediction Project (WEPP) model using 137 Cs‐estimated spatially distributed erosion data and quantified the effects of slope length on erosion along rangeland hillslopes. Eight rangeland hillslopes in midwestern Oklahoma were selected. The WEPP rangeland model was parameterized with observed soil and vegetation data. One downslope transect was sampled for each hillslope. At each sampling position, seven samples along a contour line were composited to represent the 137 Cs inventory for that slope position to reduce random spatial variation. Both methods predicted low soil erosion rates, with the maximum erosion rates being near 2 Mg ha −1 yr −1 . The erosion rates predicted by the two methods were significantly correlated at P = 0.01, and the medians were not significantly different; however, a paired t ‐test showed that WEPP predicted significantly lower erosion rates than the 137 Cs method. More importantly, the WEPP‐predicted soil erosion patterns in response to slope length agreed very well with those predicted by the 137 Cs method. The loci of the maximum and minimum erosion rates were similar between the two methods for seven transects. The WEPP rangeland model predictions for the spatial patterns of relative soil erosion intensity along a hillslope compared favorably with 137 Cs method estimates.