塘库沉积的137Cs法断代测定三峡库区小流域产沙量

本文以三峡库区重庆忠县黄冲子小流域和工农沟小流域为研究区域,依据塘库修建时间(1955年)、退耕还林工程启动时间(2000年)和~(137)Cs示踪技术,确定了小流域不同时期产沙量及产沙模数,并分析比较了不同小流域的塘库沉积物~(137)Cs含量和产沙模数。研究结果表明,黄冲子小流域和工农沟小流域1955~1963年、1963~2000年、2001~2014年的产沙模数均呈下降趋势,库区小流域生态环境得到明显改善;黄冲子小流域不同时期产沙模数均大于工农沟小流域,工农沟塘库沉积物1963年~(137)Cs峰值和表层泥沙~(137)Cs浓度均小于黄冲子塘库,主要与小流域的土地利用类型以及侵蚀方式有关。在以后的研究中,应该加强库区小流域沟道侵蚀产沙量的定量估算,为长江经济带生态环境建设提供参考依据。

Sediment Yields Measured by Pond Deposits with Application of a 137Cs Fingerprinting Technique for Small Catchments of the Three Gorges Reservoir Region

A study on sediment yields and sediment yield moduli during different periods of 1955-1963, 1963-2000 as well as 2001-2014 forHuangchongzi and Gongnonggou catchments in Zhongxian County, the Three Gorges Reservoir Region (TGRR) by using ¹³⁷Cs technique was conducted in this paper, based on the start-time of Grain to Green project (2000) as well as pond construction date (1955). Results indicate that sediment yield moduli of 1955-1963, 1963-2000, and 2001-2014 for Huangchongzi and Gongnonggou catchments display declining trends. The ecological environment of the catchments has become better than before. Sediment yield moduli of different periods for Huangchongzi catchment were apparently higher than those for Gonnonggou catchment. However, in 1963 year peak value of ¹³⁷Cs and surface sediment ¹³⁷Cs activities for Gonnonggou pond sediment core are both much lower than those for Huangchongzi catchment, which may be caused by different land use types and erosion pattern. In the future, the research on quantifying sediment yield from gully erosion should to be paid more attention to. This study could provide scientific reference for the ecological environmental construction of the Yangtze River Economic Belt.