|Baffaut, Claire - PURDUE UNIVERSITY|
|Govers, Gerard - UNIVERSITY OF LEUVEN|
Submitted to: European Soil Conservation Society
Publication Type: Proceedings
Publication Acceptance Date: March 21, 2000
Publication Date: N/A
Technical Abstract: Soil conservation measures may be better designed with the knowledge of daily distributions of rain- and runoff-induced erosion. Collecting reliable data to determine daily erosion distributions is expensive and requires a long period of time. However, new process-based soil erosion models have the potential to simulate extended records. The objectives were to analyze frequency distributions of measured daily soil loss values, to determine if the Water Erosion Prediction Project (WEPP) model accurately reproduced statistical distributions of the measured daily erosion series, and to show how such analyses can be used to determine the relative contribution of low return frequency events to the total erosion at a site. A Log-Pearson type III (LP III) distribution was fitted to measured and WEPP-predicted soil loss values from 6 sites for periods ranging from 6-10 years. Cumulative soil loss as a function of storm recurrence interval was used to show the relative contributions of large and small storms to total soil loss at each site. Results showed that measured and predicted frequency curves fell within the 95% confidence range of the LP III distributions. This was true using weather data from the site as well as when using synthetic weather series generated with the CLIGEN model. The results were encouraging in terms of using WEPP in conjunction with CLIGEN to generate long-term daily soil loss frequency distributions, which can contribute towards alleviating the problem of having only a short monitoring period for measured erosion. Cumulative soil loss results indicated that large storms contributed a major portion of the erosion under conditions where cover was high, but not necessarily under conditions of low cover.