淤地坝系对流域水沙动力过程调控作用与模拟研究

发布时间：2018-03-07 05:12

本文选题：淤地坝系　切入点：MIKE模型　出处：《西安理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：淤地坝系在黄土高原水土保持生态建设中发挥着重要作用,科学认识淤地坝系对流域水沙过程的影响,对保障淤地坝系安全运行、维护黄土高原生态安全具有重要意义。本研究以陕西省绥德县王茂沟流域为研究对象,采用统计分析、原型观测及数值模拟等手段,研究了坝地土壤水分分布规律,分析了淤地坝系对沟道侵蚀动力过程的调控作用,阐明了淤地坝系调蓄径流、拦泥减沙的作用机理。取得的主要结论如下:(1)坝地的分层淤积结构具有明显的阻水作用,使土壤水分呈层状分布。坝地表层(0-20 cm) 土壤水分空间分布均属于中等变异,0-240 cm 土层土壤平均含水量变化范围为9.92%-23.70%,随深度的增加,土壤平均含水量表现为先减小后增大;坝地土壤水分在空间上具有明显的分层现象,且坝前各层土壤含水量均明显高于坝中和坝尾,在时间上属于中等变异;MIKE SHE模型很好地模拟了坝地土壤水分的层状分布,在坝地分层土壤结构中,质地较细的泥沙层持水能力强于质地较粗的泥沙层,细颗粒泥沙含水量明显高于粗颗粒泥沙。(2)基于MIKE SHE和MIKE 11耦合建立的流域水文模型可以较好地模拟黄土高原小流域次暴雨洪水过程。模拟结果表明,淤地坝系建设使洪峰减小65.34%,洪量减少58.67%,洪水过程坦化;骨干坝、中型坝和小型坝的建设分别使洪峰减小27.28%、33.39%、40.13%,洪量减少2.18%、27.08%、44.89%;串联、并联、混联三种坝系级联方式分别使洪峰减小64.30%、75.38%、83.31%,洪量减少37.52%、50.88%、52.68%;淤地坝建设改变了洪水历时,骨干坝和中型坝的建设增加洪水历时,而小型坝缩短洪水历时。并联坝系不会改变洪峰出现时间,串联和混联坝系使洪峰滞后10min出现,串联坝系减小了洪水历时,并联和混联坝系增加了洪水历时。(3)淤地坝系明显改变了坝前坝后的水动力过程,降低了沟道径流侵蚀动力。骨干坝、中型坝、小型坝的修建使坝前的流速、径流剪切力、径流功率、单位水流功率等水动力参数急剧减小;不同坝型对坝后水动力过程影响不同,其中骨干坝后各水动力参数减幅相对较小。坝系建设改变了沟道侵蚀动力的空间分布,未建坝时,流域出口的侵蚀动力最大,坝系建成后,流域出口的侵蚀动力最小,其余坝系布局介于这两种工况之间。不同坝系级联方式对流域侵蚀动力的调控作用也不同,串联、并联、混联坝系使流域出口最大流速分别减小57.83%、69.40%、78.35%,最大径流剪切力分别减小82.23%、90.64%、95.32%,最大径流功率分别减小92.50%、97.14%、98.99%,其中混联坝系的减幅最大。(4)坝系建设明显减小了流域的径流侵蚀功率,减少了流域的输沙量。沟道未建坝时,流域多条支沟的径流侵蚀功率大于主沟,主沟沿程径流侵蚀功率大致介于2×10-4m4/(s.km2)～5×10-4m4/(s.km2)之间;坝系建成后,流域的径流侵蚀功率明显减小,径流侵蚀功率从主沟上游到下游表现为先减小后增大的趋势。与流域不建坝相比,建设骨干坝、中型坝、小型坝分别使输沙模数减少24.74%、47.11%和64.11%,其中小型坝减幅最大,坝系全部建成后流域输沙模数减少比例最大,达83.92%。
[Abstract]:Warping dam system plays an important role in the ecological construction of soil and water conservation in the Loess Plateau, the scientific understanding of the impact of runoff and sediment process of warping dam system, to ensure the safe operation of warping dam system, plays an important role in maintaining ecological security of the Loess Plateau. Based on the case study of Suide County of Shaanxi Province Wang Mao Gou basin as the research object, by using statistical analysis, prototype observation and numerical simulation, study the distribution of soil water dam, analyzed control effect of Warping Dam System on gully erosion dynamic process, the warping dam system of runoff regulation, mechanism of sediment and sediment. The main results are as follows: (1) stratified structure with water silt dam resistance obviously, the soil moisture distribution is layered. The dam surface (0-20 cm) spatial distribution of soil moisture variations are moderate, 0-240 cm soil water content is 9.92%-23.70%, with the The increase of depth, the average soil water content showed decreased first and then increased; the soil moisture had obvious stratification in space, and each layer of soil moisture before the dam dam and dam were significantly higher than the tail, a moderate variation in time; MIKE SHE model is better to simulate the layered distribution of dam soil moisture in the dam, layered soil structure, fine texture of the mud sand strong water holding capacity in sediment layer of coarse texture, fine sediment water content was significantly higher than that of coarse sediment. (2) the establishment of MIKE SHE and MIKE 11 watershed hydrological model based on coupling can be used to simulate the process of small watershed in the Loess Plateau rainstorm flood. The simulation results show that the warping dam system construction so that the peak is reduced by 65.34%, 58.67% reduction in volume, flood Tanzania; Key Dam, dam construction of medium and small dam respectively. The peak is reduced by 27.28%, 33.39%, 40.13%, 2.1 reduction in volume 8%, 27.08%, 44.89%; series, parallel, hybrid three cascade dam system respectively. The peak is reduced by 64.30%, 75.38%, 83.31%, 50.88%, volume decreased by 37.52%, 52.68%; the dam construction changed the flood duration, the construction of key dams and medium-sized dams increase flood duration, and shorten the duration of flood. The dam type small shunt the dam system will not change the flood peak time series, and hybrid dam system make the peak lag 10min series, the dam system reduces the flood duration, parallel connection of dam system increases the duration of flood. (3) warping dam system significantly changed before the dam dam after water dynamic process, reducing the channel runoff erosion power. Key Dam, medium small dam, dam construction of the dam before the runoff shear stress, flow rate, runoff power, unit flow power and other hydrodynamic parameters decrease rapidly; different dam type has different effects on the dynamic process of water dam, the dam after the bone dry hydrodynamic parameters relative reduction Small. Dam construction changed gully erosion dynamic spatial distribution, no dam, basin outlet erosion dynamic maximum dam system after the completion of the watershed outlet erosion power minimum, the other dam system layout between these two conditions. The effects of different methods on the cascade dam system of erosion power is also different. Series, parallel, hybrid dam system make the basin outlet maximum velocity is decreased by 57.83%, 69.40%, 78.35%, the maximum runoff shear stress was reduced by 82.23%, 90.64%, 95.32%, the maximum runoff power is decreased by 92.50%, 97.14%, 98.99%, the hybrid dam is the largest reduction. (4) construction of dam system significantly reduces the power erosion basin runoff, reduce the amount of sediment in the river channel. Without dam, runoff many branch ditch erosion power is greater than the main channel, the main Gouyan process of runoff erosion power roughly between 2 * 10-4m4/ (s.km2) ~ 5 * 10-4m4/ (s.km2) between the dam system; After the completion of the watershed runoff erosion power decreases, runoff erosion power from the main channel upstream to downstream is decreased first and then increased. Compared with the river basin dam, the construction of Key Dam, medium small dam dam, respectively. The sediment modulus decreased by 24.74%, 47.11% and 64.11%, of which a small dam the largest reduction, dam system after the completion of the whole sediment modulus decrease the largest proportion, up to 83.92%.

【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157.31

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