2007 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to develop and validate mathematical relationships to describe the interaction of cropping systems with soil freezing and thawing and the resulting effects on runoff, erosion and water quality in order to improve predictive models. 1b.Approach (from AD-416) In consultation with the ADODR, hydrological and erosion models will be developed, and field and laboratory experiments will be designed and conducted in order to test hypotheses and determine parameters for winter process components in these research and application models. Consultation with and review by other researchers and users will ensure the models meet specified needs. Results of this research will be jointly reported in the scientific literature, technology transfer documents and training activities. Documents Specific Cooperative Agreement with WSU. 3.Progress Report This report documents research conducted under a specific cooperative agreement between ARS and the Biological Systems Engineering Dept. of Washington State University. Additional details of research can be found in the report for the parent CRIS 5348-12000-008-00D EROSION PREDICTION TECHNOLOGY TO ENHANCE CONSERVATION PLANNING. The USDA-ARS WEPP (Water Erosion Prediction Project) model with energy-based winter routines was tested with Pullman, Washington weather and plot data collected during 2003-2006. The WEPP model with energy-based winter routines reasonably reproduced the observed snow, frost and thaw depths, and runoff. Progress is reviewed at monthly meetings with the cooperator and staff. 4.Accomplishments None 5.Significant Activities that Support Special Target Populations None