Assessment of sediment and erosion rates by using the caesium-137 technique in a Chinese polygonal karst depression.

Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants; yet the sedimentology of many depressions is not well understood in the world. In this paper, the Cs technique was employed to estimate recent sedimentation rates in a Chinese polygonal karst depression. The results indicate that the sediment deposition rates ranged from 0.91 to 1.97 mm year from 1963 to 2007, and the average sediment deposition rate and specific deposit yield were estimated to be 1.47 mm year and 20 t km year, respectively. These results are consistent with the local monitoring data of runoff fields, which confirms the validity of the overall approach. This shows that the soil loss rate is very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the space distribution of surface soil and Cs inventories are affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon, which exists widely in karst areas, and it is significantly different from other places. [ABSTRACT FROM AUTHOR]