Grassed waterway planning model evaluated for agricultural fields in the western coal field physiographic region of Kentucky

Abstract

Precision conservation technologies can provide useful information to producers and conservationists as they develop crop management plans in agricultural systems. A recent study proposed a statistical model for waterway planning on a farm in the Outer Bluegrass physiographic region of Kentucky. The logistic regression model identified where channel erosion was likely to occur based on elevation-derived terrain attributes. The objective of this study was to test that model in fields located in the Western Coal Fields physiographic region, where soils differ substantially. Elevation measurements were collected across four fields with a real-time kinematic global positioning system in this region of Kentucky and were processed to calculate terrain attributes for each field. Model predictions corresponded well with known areas of concentrated flow erosion (i.e., maps of existing waterways, surface drains, and observations of erosion). Observations of the individual terrain attributes used to calculate the probability of erosion suggested that all terrain attributes were important. However, only one or two attributes were observed to be useful for predicting existing waterways or eroded areas at each location. Average misclassification rates for areas of the study fields outside existing waterway boundaries (11%) were comparable to the previous study conducted in the Outer Bluegrass Region (14%) where the model was developed. Areas of the study fields inside existing waterway boundaries had a higher average misclassification rate (45%), which was greater than the previous study (16%); however, visual observations revealed that the model successfully identified the general shapes of existing waterways. The geographic inference space of the waterway planning model was larger than expected, as it appeared to be applicable across a broader region of Kentucky than initially anticipated. As found in similar studies on the coincidence of eroded areas with terrain attributes, the modeling procedure evaluated herein appeared to have the potential to be an effective tool to help conservationists identify areas where waterways should be located on some Kentucky landscapes.