淤地坝“淤满”后的水沙效应及防控对策

发布时间：2018-10-20 09:21

【摘要】：黄土高原大规模的淤地坝建设在减少黄河泥沙以及改善区域生态环境方面发挥了巨大作用。但是,在淤地坝"淤满"的极端条件下,关于其水沙效应变化及防治对策的研究还较少涉及。经分析,淤地坝"淤满"后:1)坝控范围内坡度降低,径流长度减少,沟道比降降低,而横断面由原来的"V"型沟道,演变为"U"型沟道;2)以关地沟4号坝为例,使用RUSLE计算,修建淤地坝前,坝控范围内平均每年土壤侵蚀模数为4 472 t/(km~2·a),淤满后,土壤侵蚀模数下降至4 019 t/(km~2·a),降幅约10%,"原地"减蚀作用显著,从修建至淤满阶段,拦沙作用巨大;3)淤地坝淤满后,坝地流速显著降低,从修建淤地坝前的0.83 m/s降至0.27 m/s,但坝体外坡的流速显著增加,特别是坡底,最大流速可达3.76 m/s;4)淤地坝淤满后,淤地坝"异地"减蚀作用会降低。基于上述变化,针对淤地坝淤满后的极端条件,本文提出如下防治对策:1)以小流域为单元,以溢洪道为主体,完善沟道排洪设施布设,提高支沟内以及支沟与主沟的连通度,提升排洪能力;2)遵循"因地制宜"原则,科学合理植树种草、修建梯田,加强坡面治理,减少坡面来水来沙,消耗和分散坡面来水侵蚀能量,降低坝地淤满后被损毁的风险;3)采取"截水沟和排水沟相结合,工程措施和植物措施相结合"的方法,做好坝体陡坡防治,提高坝体外边坡植被覆盖度。研究结果以期为黄土高原淤地坝建设提供理论支撑。
[Abstract]:The large-scale silt dam construction on the Loess Plateau has played a great role in reducing the sediment of the Yellow River and improving the regional ecological environment. However, under the extreme condition of silt fill of silt dam, the research on the change of water and sediment effect and the countermeasures of prevention and control are seldom involved. The results show that: 1) the slope, the length of runoff and the ratio of channel to channel are decreased, and the cross section is changed from "V" type channel to "U" type channel, 2) taking Guandigou No. 4 dam as an example, the calculation is done with RUSLE. Before the construction of the silt dam, the average annual soil erosion modulus in the dam control range is 4 472 t / (after km~2 a), silting, the soil erosion modulus decreases to 4 019 t / (km~2 a), decrease is about 10 t /), and the effect of in situ erosion reduction is remarkable, from the construction to the silt fill stage. (3) after silt fill, the flow velocity of the dam decreased significantly, from 0.83 m / s to 0.27 m / s before the silt dam was built, but the velocity of flow on the outside slope of the dam increased significantly, especially at the bottom of the dam, with the maximum velocity of 3.76 m / s 路s ~ (4) when the silt dam was filled, The anti-erosion effect of silt dam will be reduced. Based on the above changes, in view of the extreme conditions after the silt fill of the silt dam, this paper puts forward the following countermeasures: 1) taking the small watershed as the unit, taking the spillway as the main body, improving the layout of the drainage facilities of the channel, improving the connectivity between the branch ditch and the main ditch, and improving the connection between the branch ditch and the main ditch. 2) following the principle of "taking measures according to local conditions", scientifically and reasonably recommending planting trees, building terraces, strengthening slope management, reducing the amount of water and sand coming from the slope, consuming and dispersing the erosion energy from the slope. To reduce the risk of damage after silt fill, 3) to adopt the method of "combination of intercepting ditch and drainage ditch, combining engineering measure with plant measure" to prevent and cure the steep slope of dam body and improve the vegetation coverage of slope outside the dam body. The results are expected to provide theoretical support for the construction of silt dams on the Loess Plateau.
【作者单位】：西安理工大学土木建筑工程学院;西安理工大学西北水资源与环境生态教育部重点实验室;黄河水利委员会黄河上中游管理局;西北大学城市与环境学院;
【基金】：国家自然科学基金“黄土高原淤地坝对流域侵蚀过程调控机理研究”(41401305) 国家重点研发计划“黄土高原生态、地貌多过程群体效应模拟与验证”(2016YFC0402406-ZT2),“黄土高原生态建设的生态——水文过程响应机理研究”(41330858)
【分类号】：S157.31

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