Selection of Appropriate Conversion Model for 137CS Method in Erosion and Sediment Studies In Loess Deposits in North-East of Iran

Soil erosion is one of the effective elements on soil destruction. Many empirical and theoretical models has been developed for soil erosion estimation 137 Cs technique is used as new and accurate method in this case across world. For applying this technique on computing erosion and sediment rate، an appropriate conversion model should be selected. For this propose in this study proportional، mass balance I and mass balance II were used in cultivated soils، also in uncultivated soils profile distribution and diffusion ad migration were used. The result shows that in cultivated soils mass balance I has the highest estimation، whereas in uncultivated soils profile distribution estimate this rate more than diffusion and migration model. While the SDR estimation by all three models are similar in cultivated soils، this result is not the same at uncultivated soils، but the models results indicate 16% difference. In general proportional model and distribution profile model are preferred for following reasons: less coefficient of variation (CV)، less parameters needed، and similar SDR estimation with other models.