Ephemeral Gullies Predicted with Terrain Attributes Derived From USGS DEMs.

Grassed waterways are effective tools for reducing ephemeral gully erosion in agricultural fields. A recent study proposed a statistical erosion model for a farm field located in the Outer Bluegrass Physiographic region of Kentucky. The model identified where channel erosion was likely to occur based on the value of real-time kinematic (RTK) global positioning system (GPS) derived terrain attributes. The objective of this study was to assess the performance of this modeling approach when terrain attributes were derived from USGS 10-m DEMs rather than RTK GPS. Our initial attempts to fit models to the USGS data yielded poor results. However, when a model developed with the RTK GPS data was fit to the USGS dataset, most of the erosion features in the field could be predicted. However, they were not as well defined as when they were predicted with the RTK data. This work demonstrated USGS 10-m elevation data can be used to identify where channel erosion is likely to occur in agricultural fields. This is significant because USGS elevation data can be freely obtained over the Internet whereas RTK elevation surveys are expensive and time consuming to create.