Locating Eroded Waterways with United States Geological Survey Elevation Data

Concentrated water flow causes considerable erosion in agricultural fields. The objective of this study was to test whether a stochastic modeling approach could be used to determine the location of erosion channels based on terrain attributes derived from 10-m level-2 U.S. Geological Survey (USGS) elevation data. Logistic regression was used to develop models that predicted where erosion was likely to occur based on digital terrain attributes derived from the elevation data. The model was fit using georeferenced field observations of soil erosion. A simple two-variable model was developed for predicting erosion channels that included two topographic attributes: the length-slope factor (t score = 9.7) and the topographic wetness index (t score = 11.4). Leave-one-field-out cross-validation (average of 22% false positives and 34% false negatives) confirmed that models correctly identified many of the eroded waterway features but did not accurately predict their shapes. This work suggests that erosion indices developed from freely available 10-m elevation data could be used to help conservation planners identify erosion channels in some agriculture fields. The USGS National Elevation Dataset (NED) provides free, seamless elevation data on 10- and 30-m grid for most of the United States.