黄土丘陵区土地利用/覆被变化的侵蚀产沙响应示踪研究
文献类型：学位论文
| 作者 | 龙翼
|
| 学位类别 | 博士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 张信宝 |
| 关键词 | 产沙模数 植被恢复 孢粉示踪 137Cs示踪 |
| 其他题名 | A Study on Responses of Soil Erosion and Sediment Yield to Land Use and Cover Change by Using Tracer Technique in the Rolling Loess Plateau, China |
| 学位专业 | 自然地理学 |
| 中文摘要 | 虽然植被对水土流失的控制机制已得到广泛的认同，但对植被恢复措施减蚀效益的定量评估尚存在较多分歧。而历史时期黄土高原侵蚀的研究，研究手段有限。黄土高原分布着很多现代淤地坝和古聚湫，坝库内沉积了历年的暴雨洪水产沙。通过区分洪水沉积旋回并确定洪水旋回形成的时间，即可查明相应时间段的流域产沙状况。基于此认识，我们选择有退耕前后坝库淤积的吴起榆树沟小流域和形成时间有明确记载的子洲黄土洼古聚湫，采用核素、孢粉示踪方法，查明了退耕前后榆树沟流域侵蚀产沙的变化和明代中期黄土洼流域的产沙模数。主要研究结论如下：1）退耕前后坡面土壤侵蚀强度差异。分别选取未退耕的坡耕地和植被覆盖良好的草坡地为研究样地，采用137Cs核素示踪法，查明未退耕坡耕地的土壤侵蚀模数达6600 t/km2 a，草坡地土壤侵蚀模数仅为397 t/km2 a，植被恢复的坡面减蚀效益可达94％以上。2）退耕前后小流域侵蚀产沙差异。选择有退耕前后坝库淤积的吴起榆树沟流域为研究小流域，通过分析沉积剖面137Cs活度、孢粉浓度的变化，并结合泥沙粒度分析，区分洪水旋回，查明榆树沟小流域退耕前的年输沙模数高达20953 t/km2 a。退耕后年输沙模数迅速降低到1773 t/km2 a。前后相差达91.46％。退耕后坝库沉积泥沙137Cs平均含量少于退耕前，表明退耕后沟间地相对来沙量减少，而沟谷地相对来沙量增加。3）历史时期黄土丘陵区小流域侵蚀产沙状况。选择陕北子洲黄土洼古聚湫为研究对象，根据聚湫坝库泥沙沉积剖面孢粉浓度和泥沙粘粒含量的变化，在总厚12.73m的沉积泥沙剖面中区分出54个洪水沉积旋回，以年末次洪水旋回顶部特有的冻融扰动现象为依据，54次暴雨为31个年度内形成。通过求算旋回淤沙体积，查明明代中期黄土洼流域年产沙模数介于968 t/km2a －55579 t/km2a，平均12629 t/km2a，明代该区域的年产沙模数与现代年产沙模数接近。 |
| 英文摘要 | The prevent mechanism from the soil and water loss of vegetation rehabilitation is acknowledged, but the estimation of the protection in quantification is different among the researches., As while the method to research the historical soil erosion in Loess Plateau is limited. There are many check dams and nature reservoirs in Loess Plateau. By distinguishing the sediment layers of floods and settling down the responding time, the sediment yields in the responding time will be found out. Based on that standpoint, the Yushu gully with modern check dams built before and after the vegetation rehabilitation and the Huangtuwa gully with a nature reservoir are selected as research regions. Using the 137Cs and the pollen as tracer, the changes between the sediment yields before and the after the vegetation rehabilitation are discussed and the sediment yield in middle of Ming dynasty is investigated. The main conclusions drawn in this theme are as follow:1.Selecting a bare crop land and a grass land as research sample land, the soil erosion rate of two lands are investigated by 137Cs tracer technique, respectively. The soil erosion rate of the bare crop land is 6600 t/km2 a and that of the grass land is only 397 t/km2 a. 2.Selecting the Yushu gully in Wuqi County with check dams built before and after vegetation rehabilitation as research small catchments, by analysis the content changes of 137Cs and pollen in the sediment profile, the flood sediment layers are identified. The sediment yields before and after vegetation rehabilitation are 20953 t/km2 a and 1773 t/km2 a. The latter is 91.46% less than the former.3.Selecting the Huangtuwa gully in Zizhou County as research small catchment, the sediment yield of this catchment in middle of Ming dynasty is ascertained. By analysis the content of pollen and clay in the sediment profile, 54 sediment layers of floods are distinguished. Using the “frozen been curd” phenomenon as indication, it is ascertained that the 54 sediment layers are formed in 31 years. By calculating the volume of every sediment layer, the sediment yields of Huangtuwa catchment in middle of Ming dynasty are between 968 t/km2a and 55579 t/km2a, the average of sediment yields in those 31 years is 12629 t/km2a. The soil erosion rate in middle of Ming dynasty is similar to the modern erosion rate of this region. |
| 学科主题 | 水土保持学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-15 |
| 分类号 | S15;X82 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2215]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 龙翼. 黄土丘陵区土地利用/覆被变化的侵蚀产沙响应示踪研究[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2008. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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