2007 Annual Report 1a.Objectives (from AD-416) Plan laboratory, field, and modeling studies to quantify erosion processes by concentrated flows in small agricultural areas with the final goal of improving erosion control practices. 1b.Approach (from AD-416) Evaluate runoff and landscape properties such as topographic and soil profiles, and vegetative cover in field areas susceptible for ephemeral and edge-of-field gully erosion development. Complement field monitoring with laboratory measurements to characterize and quantify headcut migration, gully growth, and sediment yield from the selected areas. Description of water and sediment fluxes and sediment transport processes using models will allow the interpretation of the experimental results and their extrapolation to different conditions. Modeling efforts will cover a range of scales using analytical, BGK lattice schemes, and enhancements to the AnnAGNPS model. 3.Progress Report This report serves to document research conducted under a non-funded Specific Cooperative Agreement between ARS and the University of Cordoba, Spain. This agreement served as a vehicle for the cooperator from the University of Cordoba to visit the National Sedimentation Laboratory and participate in research supporting the ARS AGNPS modeling project. Additional details of research can be found in the report for the in-house project 6408-13000-017-00D, "Integrated Assessment and Analysis of Physical Landscape Processes That Impact The Management Of Agricultural Watersheds." Erosion by concentrated flow has been shown to be a significant contributor to total soil loss in Spain and U.S. landscapes. Identifying the initiation point of ephemeral gully erosion on diverse landscapes can provide valuable information in determining the proper placement of appropriate conservation practices used to control ephemeral gully erosion. A six hectare olive orchard watershed in Spain was evaluated for the location and length of 17 gullies within the watershed. The initiation and extent of these gullies were then compared to an automated topographic analysis approach of identifying potential ephemeral gullies on the landscape. Predicted results based on an evaluation of various topographic analysis threshold values produced a good agreement with observed ephemeral gully locations. Improvements in the automated approach were identified to reflect the need to consider the effect of soil infiltration conditions that may have a much larger influence than drainage area.