黄丘区坡面退耕与淤地坝对坡沟系统侵蚀产沙的阻控机理

Aiming at the characteristics of soil and water loss and its control in the loess hilly-gully region, the project will be executed in the different types of check dam controlled slope-gully systems. Based on the theories and methods in disciplines of soil erosion, soil science, and vegetation ecology, the features of underlaying surface in gully-slope systems, runoff and sediment yield on abandoned slopes, gully erosion development, siltation process of check dams, erosion sediment yield of the upstream/downstream gully affected by check dam, and runoff and sediment discharge in the export of slope-gully system will be surveyed or monitored. Then, the characteristics of vegetation and soil, runoff and sediment yield on the abandoned slopes with different vegetation restoration conditions, and their influences on gully erosion development will be analyzed. The response of siltation process of check dam to vegetation succession, and the effect of check dam on erosion sediment yield in the gully will be investigated. The blocking and controling roles and mechanisms of slope land abandonment and check dam on erosion sediment yield of slope-gully system will be revealed. The characteristics of erosion sediment yield in slope-gully system under different combinations of abandoned slopes and check dams will be clarified. This study will provide reference basis for evaluation of the contribution of 'Grain for Green' project and check dam construction on the Loess Plateau to the reducing of sediment and runoff discharge in the Yellow River. This study has important theoretical and practical significance in the ecological environment restoration and sustainable development on the Loess Plateau, sediment management and healthy operation of the Yellow River, and the construction of ecological civilization in China.

针对黄土丘陵沟壑区水土流失及其治理特点，以不同类型的坝控坡沟系统为对象，采用土壤侵蚀、土壤与植被生态等学科的理论与方法，在对坡沟系统下垫面特征、退耕坡面产流产沙与沟蚀发展特征、淤地坝泥沙淤积过程及其上下游作用区沟道的侵蚀产沙特征、及坡沟系统出口径流泥沙量进行调查与监测的基础上，分析退耕坡面不同植被恢复条件下的植被与土壤特征、产流产沙特征及其对沟蚀的影响，研究淤地坝淤积过程及其对退耕坡面植被恢复演替的响应关系、及淤地坝对其上下游作用区沟道侵蚀产沙的影响，揭示退耕坡面植被恢复与沟道淤地坝对坡沟系统侵蚀产沙的阻控作用与机理，阐明不同退耕坡面与淤地坝组合作用下的坡沟系统侵蚀产沙特征，为评价黄土高原退耕还林（草）工程与淤地坝建设对黄河水沙减少的贡献提供参考依据，对黄土高原生态环境恢复与可持续发展、黄河泥沙管理与健康运行、及我国生态文明建设具有重要的理论和现实意义。

本项目针对黄土丘陵沟壑区水土流失及其治理特点，采用土壤侵蚀、土壤与植被生态等学科的理论与方法，研究了坡面退耕与淤地坝对坡沟系统侵蚀产沙的阻控机理。依据对800多个退耕坡面的样地调查与分析，分析了不同恢复阶段特别是退耕还林（草）工程实施15年后自然与人工恢复坡面的植被与土壤特征及其恢复力；并通过2014-2017年对30个滑坡面土壤与植被的调查与观测，探明了沟坡滑坡面的植被恢复特征与可恢复性。采用侵蚀针监测与野外量测（2013-3016年），研究了不同植被类型的退耕坡面土壤侵蚀特征、极端暴雨下沟坡的滑坡侵蚀及滑坡面上的细沟侵蚀特征；通过2016-2017年在安塞坊塌、后崾崄和宋家沟小流域的26条侵蚀沟插钎测量，探讨了侵蚀沟的沟头溯源侵蚀、沟谷拓宽、沟沿线上方周边坡面及沟底侵蚀特征；依据径流小区观测（2015-2017年），明确了不同植被类型的退耕坡面与坡沟系统的产流产沙特征及其对植被恢复的响应。通过在安塞坊塌坝系流域的淤地坝钻探、淤积层次划分及其与次降雨事件对应关系识别，探明了淤地坝的淤积过程与拦沙作用，反演了坝控流域侵蚀产沙变化特征；在对建于2005-2008年间17座淤地坝淤积量测量及2014-2016年对7座典型淤地坝淤积厚度监测的基础上，结合相关文献对1957-2014年间44座淤地坝数据的整合，明确了坡面退耕对坝控流域侵蚀产沙及淤地坝拦沙潜力的影响。从退耕坡面尺度、坡沟系统尺度和坝控流域尺度，阐明了坡面退耕与淤地坝对坡沟系统侵蚀产沙的阻控机理。本研究结果可为评价黄土高原退耕还林（草）工程与淤地坝建设对黄河水沙减少的贡献提供参考依据，对黄土高原生态环境恢复与可持续发展、黄河泥沙管理与健康运行、及我国生态文明建设具有重要的理论和现实意义。