Remotely Sensed Channel Emergence with Both Till and No-Till Management Systems

Author(s): Wells, R.; Momm, H.; Vieira, D.; Bingner, R.

Ephemeral channels appear in agricultural fields under a host of conditions. The spatial emergence is primarily driven by topography, tending to increase or decrease the erosive forces of runoff, whereas the temporal component, represented by geomorphologic response over time, is much less understood. In this study, agricultural fields in Iowa were selected based upon potential for channel formation and management practices. Aerial topographic surveys were collected following planting in till and no-till managements, where localized climate measurements were obtained, then another aerial topographic survey was collected a month later. A novel surveying approach was designed by combining unmanned aerial vehicles (UAVs) with digital photogrammetry, differential global coordinate system (DGPS), and integration of on- and off-field ground control points. Each survey was anchored to a global coordinate system (GPS) via targets surveyed using GPS equipment and established static field monuments, ensuring that coordinate system solutions from the two aerial surveys of the same site were horizontally and vertically aligned. Custom algorithms were employed to process generated point clouds and produce geospatial datasets at centimeter spatial resolution. Difference mapping of the temporal topographic surveys combined with the climate measurements from each location provides guidance for temporal erosion components (i.e. the erodibility parameters) within erosion models such as RUSLE2. Conservation planning can be improved through time series of high resolution topography surveys that provides enhanced information on where problems are within agricultural fields and data to erosion management technology needed to evaluate conservation practices targeted to the existing problems.

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