Assessment of sediment yield in a small karst catchment by using ^(137)Cs tracer technique  

作　　者：Dong-chun YAN Xin-bao ZHANG An-bang WEN Xiu-bin HE Yi LONG 

机构地区：[1]Key Laboratory of Mountain Environment Evolution and Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences [2]Graduate University of Chinese Academy of sciences

出　　处：《International Journal of Sediment Research》2012年第4期547-554,共8页国际泥沙研究（英文版）

基　　金：supported by the 973 program(Grant No.2006CB403203);the Chinese Science and Technology Ministry(Grant No.2008BAD98B01)

摘　　要：There is very thin soil layer in karst rocky desertification areas in Southwest China, sediment deposition and sediment yield in the karst area affects the development of vegetation greatly. In the present study, the 137Cs technique was used to assess the rate of sediment deposition and sediment yield in a small karst catchment. The 137Cs inventory within the depression varied between 800 m2 and 2,200 Bq m-2, with the mean value of 1,500.1 Bq m-z. The 137Cs reference inventory at a nearby reference site was 805.9 Bq m-2. It could be inferred to that sediment deposition had occurred in the catchment. The mean depth of sediments deposition in the depression was 6 cm and the deposition rate was approximately 0.13 cm yr-2. The analysis of the topographic characteristics of the catchment revealed that the sediment deposition occurred mainly at the lower part of the small catchment. Although, there was a sinkhole in the depression, little sediment had drained out with rtmoffthrough the sinkhole, because the local people built ridges around the sinkholes for storing water. According to this, sediment yield rate in the small catchment was estimated to be approximately 19.25 to 27.5 t km2 yr^-1, and the extremely low sediment yield was maybe the main obstacle to vegetation restoration in karst rocky desertification areas.There is very thin soil layer in karst rocky desertification areas in Southwest China, sediment deposition and sediment yield in the karst area affects the development of vegetation greatly. In the present study, the 137Cs technique was used to assess the rate of sediment deposition and sediment yield in a small karst catchment. The 137Cs inventory within the depression varied between 800 m2 and 2,200 Bq m-2, with the mean value of 1,500.1 Bq m-z. The 137Cs reference inventory at a nearby reference site was 805.9 Bq m-2. It could be inferred to that sediment deposition had occurred in the catchment. The mean depth of sediments deposition in the depression was 6 cm and the deposition rate was approximately 0.13 cm yr-2. The analysis of the topographic characteristics of the catchment revealed that the sediment deposition occurred mainly at the lower part of the small catchment. Although, there was a sinkhole in the depression, little sediment had drained out with rtmoffthrough the sinkhole, because the local people built ridges around the sinkholes for storing water. According to this, sediment yield rate in the small catchment was estimated to be approximately 19.25 to 27.5 t km2 yr^-1, and the extremely low sediment yield was maybe the main obstacle to vegetation restoration in karst rocky desertification areas.

关 键 词：137Cs Sediment deposition Sediment yield Karst depression Southwest China 

分 类 号：S157[农业科学—土壤学]