基于^(137)Cs、^(210)Pb和CSLE的三峡库区小流域土壤侵蚀评估

Evaluation of Soil Erosion in Small Watershed of the Three Gorges Reservoir Region by Using ^(137)Cs,^(210)Pb and CSLE

综合应用137Cs和210Pb技术和中国土壤流失方程CSLE(Chinese soil loss equation)进行三峡库区腹地工农沟小流域土壤侵蚀的定量评价研究,尝试基于核素示踪技术计算的土壤侵蚀模数评估CSLE在库区林地小流域的估算效果。结果表明:(1)借助210PbexCRS计年模式获得了工农沟塘库沉积柱芯不同质量深度的沉积年代,与137Cs 1963年断代结果相比基本一致,定年结果可靠;(2)基于核素示踪技术(137Cs和210Pb)计算的小流域2002—2014年土壤侵蚀模数为269.09t/(km2·a),侵蚀强度属于微度侵蚀,年土壤侵蚀量为22.87t/a;(3)依据CSLE和考虑沟蚀因子的CSLE估算的小流域2002—2014年土壤侵蚀模数分别为256.07t/(km2·a)和317.53t/(km2·a),年土壤侵蚀量分别为21.77t/a和26.99t/a;(4)与核素计算的结果相比,CSLE和考虑沟蚀因子的CSLE的估算精度均≥80%,说明采用CSLE估算库区林地小流域土壤侵蚀量结果合理。

To quantitatively evaluate soil erosion in Gongnong gully small watershed, which located in the middle part of the Three Gorges reservoir region（TGRR） of China, 137Cs and 210Pb tracer techniques, as well as Chinese Soil Loss Equation（CSLE）, were applied. This paper explored a new solution to evaluate soil erosion rates in forested watershed of TGRR through estimating soil erosion modulus by CSLE using 137Cs and 210Pb tracer techniques. The results showed that. （1）The results obtained by 210Pbex（COnstant rate of supply, CRS） and 137Cs techniques were similar for dating of pond sediment core of Gongnong gully, which proved the reliability of the dating results. （2） Soil erosion modulus and soil erosion amount between 2002 and 2014, which were calculated by 137Cs and 210Pb techniques, were 269.09 t/（km2 · a） and 22.87 t/a, respectively. The soil erosion intensity could be classified as tiny erosion. （3）Soil erosion modulus and soil erosion amount estimated by CSLE were 256.07 t/（km2 · a） and 21.77 t/a, respectively. Soil erosion modulus and soil erosion amount estimated by CSLE including gully erosion factor were 317. 53 t/（km2 · a） and 26.99 t/a, respectively. （4）The precision of soil erosion amounts estimated by CSLE and CSLE including gully erosion factor were more than 80% comparing to the results calculated by 137Cs and 210Pb techniques, which indicated that soil erosion amount estimated by CSLE was more reasonable and reliable in forested watershed of TGRR.