2007 Annual Report 1a.Objectives (from AD-416) Develop a photogrammetric technique to generate high-resolution Digital Elevation Models (DEMs) for watershed applications. Evaluate existing soil erosion models for applicability and accuracy on rangelands. 1b.Approach (from AD-416) Identify the most adequate resolution of DEMs for process-based soil erosion models, and critically investigate the differences and benefits of using publicly available versus using self generated DEMs for small watershed assessment. Watersheds between 0.5 - 7.5 ha on the Walnut Gulch Experimental Watershed will be used for the analysis. This work involves four distinct operational steps for completion:. 1)collection and assessment of existing erosion data,. 2)model sensitivity analyses,. 3)assessment of model accuracy for predicting the measured erosion, and. 4)assessment of potential for practical and useful application of the models on rangelands across the US. Existing data from small watersheds, natural runoff plots, and rainfall simulator plots will be organized in a database for model evaluation purposes. Four models will be tested (RUSLE, WEPP, KINEROS2, and HEM). Relative accuracy of the models will be compared and documented, with results reported relative to those expected in the presence of data uncertainty. Documents SCA with U. of AZ. 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and the University of Arizona. Additional details of research can be found in the report for the in-house associated project 5342-12660-004-00D, "Soil Erosion, Sedment Yield, Conservation Structures, and DSS for Sustainable Land Management on Semiarid Rangeland Watershed." Formerly 5342-12660-003-00D. Progress report. This project involved continued development of a new Rangeland Erosion and Hydrology Model. Sensitivity Analysis of the model (model testing) was accepted for publication in a scientific journal. Significant progress was also made on developing parameter estimation equations for the model. NP 201, Problem Area 4 - Integrated Soil Erosion and Sedimentation Technologies, Product 7 – Multi-scaled Modeling System Monitoring Activities ADODR met with and advised University of Arizona employees on approximately a weekly basis to ensure continued progress.