QUANTITATIVE MODEL OF SOIL-EROSION RATES USING CS-137 FOR UNCULTIVATED SOIL

By using the mass balances model and by introducing an erosion constan t (mean annual relative loss of Cs-137) and depth distribution functio n of Cs-137 in soil, a quantitative model of soil erosion rate using C s-137 loss was developed for uncultivated soils. Depth distribution pa tterns of Cs-137 in the soil profile, sampling years, and the amount o f Cs-137 fallout each year were considered. The model shows that the e stimated rate of soil erosion is controlled mainly by the distribution pattern of Cs-137 in the soil profile. By inputting different depth d istribution functions of Cs-137, the year of sampling and the differen t input fraction of total fallout value each year, several simulation results of soil loss were given. The results of numerical simulation p roved that the relationship between the rate of soil loss and Cs-137 d epletion is neither linear nor logarithmic. They are dependent on the distribution patterns of Cs-137 in the soul profile, sampling year, an d input fraction of total fallout value.