Considering the ability of Cs-137 method application to calculate soil sediment and deposition in Taseran watershed of Kabodar Ahang

Due to the importance of water erosion in reducing soil fertility many studies have been done on the quantity of this destructive phenomenon. Tamura and Rogowosky found a meaningful relation between water erosion and Cs-137 loss in soil matrix. This report was the first of application of Cs-137 method to estimate soil erosion since 1974. From 1974، the method has changed gradually and now is used in many studies. In this study، aerial photographs with scale of 1:20000 and topographic maps with scale of 1:50000 were used. 12 transects on the hilly lands (compound and uniform slopes) and 3 transects on the piedmont plain were studied. Surface samples were collected from different slope situations. The situations were collected from different slope situations. The situations were summits، shoulders، back slopes، foot slopes and toe slopes; gamma spectrometer was used to determine the Cs-137 of the samples. Soil erosion and sediment were calculated by Cochanouski (1993) Equation. Results showed that in summit، shoulder and back slope of the compound slopes، erosion is 68. 42، 45. 46 and 51. 16 Ton/ha/yr respectively. On the same situations of uniform slopes 79. 6، 65. 3 and 84. 23 ton /ha/yr of soil losses were expected. In non-erosional situations (toe slopes)، soil loss has been deposited. In foot slopes، i. e. dynamic sites، sedimentation process is more dominant than destructive ones. The correlation between USLE and Cs-137 models were statistically signification with % 95 probability.