EROSIVITY FACTOR IN THE UNIVERSAL SOIL LOSS EQUATION ESTIMATED FROM FINNISH RAINFALL DATA

Continuous rainfall data recorded for many years at 8 stations in Finland were used to estimate rainfall erosivity, a quantity needed for soil loss predictions with the Universal Soil Loss Equation (USLE). The obtained erosivity values were then used to determine the 2 parameters of a power-law function describing the relationship between daily precipitation and erosivity. This function is of importance in erosion modeling at locations where no breakpoint rainfall data are available. The parameters of the power-law were estimated both by linear regression of the log-transformed data and by non-linear least-square fitting of the original data. Results indicate a considerable seasonal (monthly) variation of the erosivity, whereas the spatial variation over Finland is rather small.