ASSESSMENT OF SOIL LOSS ON UNCULTIVATED SLOPE LAND BY USING 137CS TECHNIQUE IN THE UPPER YANGTZE RIVER BASIN OF CHINA

Radionuclides are used as tracers of sediments in areas where no plot data or field monitoring data are not available. Caesium-137 can provide important information on both soil loss rates and sediment sources. The 137Cs technique is employed to assess soil erosion rates in forest and grass lands in the Upper Yangtze River Basin, China. The study area includes 6 forestlands and 4 grasslands in 8 counties and cities over the eastern part of the basin. The 137Cs reference inventories ranged from 620.9 Bq m-2 to 2560.3 Bq m-2. For the 6 forestlands, the average 137Cs inventory over a field ranges from 960.8 Bq m"2 to 2560.3 Bq m-2. The average erosion rate is estimated from the 137Cs measurements between 0 to 588 t km-2yr-1. For the 4 grasslands, the average 137Cs inventory ranges from 119.0 Bq m-2 to 869.7 Bq m-2. The average rate of erosion from grassland varies from 0 to 4435 t km-2 yr-1. Where the erosion was more severe, the 137Cs inventory was lower. The results showed that there is no clear relation