Understanding the erosion and deposition rates is very important for designing soil and water conservation measures. However, existing methods of assessing the rates of soil loss present many limitations and are difficult to apply to in karst areas, and there is still very little data in this areas. Karst depressions comprise geomorphologically important sources and sinks for sediments and can provide the long-term history records of environmental changes. But there have been few similar studies focused on its sediments in the world. In this paper, the Cs-137 technique was employed to estimate the sediment deposition rate of karst depression to assess the surface erosion. The results indicate that the average deposition rate, deposition amount and specific deposit yield for the Yongkang catchments since 1963 were estimated to be 4Á32 mm y À1 , 3Á16 t y À1 and 20Á53 t km À2 y À1 , respectively. The results obtained were consistent with the actual monitoring data of local runoff plots, and confirm the validity of the overall approach. So it was suggested that the mean specific sediment yields of 20 t km À2 y À1 can be representative of the soil loss rates in the regions.