CALIBRATION AND TESTING OF A DAILY RAINFALL EROSIVITY MODEL

A general procedure is presented for calibrating a model for rainfall erosivity based on daily rainfall. The approach is based on probability distributions of wet-day precipitation amount and monthly erosivities which are inferred from published data summaries. The calibrated model was tested by comparisons with erosivities computed from hourly precipitation data. Model results were generally consistent with values based on hourly data and explained over 85% and 70%, respectively, of the variations in annual and event erosivities. Model results for extreme values (annual erosivities exceeded in 5% of the years and 1-in-20-year event erosivities) often substantially exceeded values computed for hourly data. To facilitate general use of the daily model, calibration coefficients were calculated for 33 sites in the eastern and central U.S.