Tools for Quantifying Rill and Ephemeral Gully Development.

Quantifying rill and ephemeral gully erosion has been a challenge.   Rills and ephemeral gullies develop at the field scale and it has been shown that both topographic and hydrologic attributes play significant roles in the channel initiation and development.   Even at the field scale, changes in channel width and depth are in one or two orders smaller than the change in channel length.   In this research we develop a simplified photogrammetry technique that can be readily deployed to quantify changes in channel morphology.  In the laboratory, we constructed a soil box that has all the surface and subsurface hydrologic controls at a 9-m long hillslope segment.   These tools allow us to quantify rill and ephemeral gully development at the field and to conduct process level research to quantify contributions from surface and subsurface hydrology in the channel development process.