共查询到19条相似文献，搜索用时 187 毫秒
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根据黄河中游、北方干旱地区流域的超渗产流水文特征和冬季积雪的累积及融化机制,提出了中大流域水流模拟模型,结合黄土地区小流域坡面产沙、汇沙和沟蚀产沙、汇沙计算公式,构成了中大流域水沙耦合模拟物理概念模型。该模型较好地处理了北方干旱地区中大流域用下渗曲线计算地面径流中存在的观测资料缺乏、数据处理量太大两大难题;考虑了大流域气候、下垫面因素空间的不均匀性和雨洪径流产沙与融雪径流产沙间的差异。经流域实测资料的模拟检验表明,模型结构较合理,模拟结果较好。 相似文献
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参照黄土区侵蚀降雨和坡面片蚀产沙特征,采用恒流泥沙输送装置模拟坡面上方来水来沙,探讨不同坡度草地含沙水流的水力学特性及其对上方来沙的拦蓄机理。结果表明,草地坡面的水流弗劳德数随坡度增大而增加,而阻力系数与坡度呈反势。按明渠水流的一般标准,不同坡度草地水流均为层状缓流。草地坡面拦沙效应随坡度增大而减小,且径流前期的减沙作用较后期更为显著。不同坡度草地坡面的出流泥沙平均直径和大颗粒(>10μm)泥沙含量均显著小于上方来沙,这说明草地的拦沙效应主要体现在对大粒径泥沙的拦蓄上。 相似文献
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夏万云 《中国地质灾害与防治学报》2022,33(1):99-106
黄土坡面侵蚀特性研究对于铁路边坡及路基防护具有重要的意义。通过银西高铁董志塬段某路基护坡坡面冲刷试验,获得了不同冲刷历时、冲刷流量、坡度等条件下的坡面冲刷结果,并对坡面流水动力学特性、坡面产沙规律、坡面产沙机理进行了分析,得出以下结论:（1）坡顶和坡底比坡面中部更易受侵蚀;30°～60°斜坡在较小的冲刷强度下也能产生较明显的侵蚀沟,宜采取45°左右的多级矮坡来减弱侵蚀强度。（2）坡面流水动力学特性分析表明,试验工况水流主要处于过渡流区;平均流速与冲刷流量、坡度呈幂函数关系;达西阻力系数与冲刷流量、坡度呈负相关,且与雷诺数相关性较低。（3）平均含沙量随冲刷流量与坡度的增大而增大,随历时近似线性增加,约20 min以后,含沙量基本稳定,此过程为坡面沟道发展阶段。（4）坡面侵蚀产沙量与侵蚀切应力、有效水流功率都呈正相关,与前者近似呈线性增大关系,而与后者近似呈幂函数关系。 相似文献
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利用野外模拟降雨试验,研究不同植被类型的侵蚀产沙、径流、地表糙度和入渗规律以及相关关系。结果表明,植被对水沙调控作用大小依次为:植物根系,整个坡面植被,坡面下部植被和坡面上部植被。林草地具有蓄水减沙的水土保持措施功效,该机制通过植物根系对水沙的调控作用实现;草地具有直接拦沙的水土保持功效,该机制通过地表植被对水沙的调控作用体现。累计产沙量随累计径流量呈幂函数递增趋势,具有很好的相关性;坡面径流产沙过程分为发育期、活跃期和稳定期3个阶段。植被覆盖度越大,地表糙度变化越小。 相似文献
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在野外放水试验条件下,利用染色法和侵蚀针法分别观测坡面流速和侵蚀产沙空间变异性。结果表明,坡面各横向断面的流速与距坡顶距离之间呈正相关,且相关性随流量增大逐渐变得显著,纵向断面流速的变异程度明显强于横向断面。总体上,上、下坡位侵蚀程度较重,而中坡位最轻;小流量时沉积作用明显,大流量时距坡顶0~2 m范围为净侵蚀区;各坡段侵蚀量与其距坡顶距离之间呈负相关;发生泥沙沉积部位随流量增大逐渐下移,细沟侵蚀量占坡面总侵蚀量的比例随流量增大不断增加。试验条件下流速为0.30 m/s时,细沟侵蚀产沙大于细沟间侵蚀,且坡面侵蚀量迅速增大。随流量增大,流速和侵蚀产沙量呈增大趋势;但在流量较大时,坡面各坡位侵蚀量与流速呈负相关,这可能与坡面中下部位粗颗粒泥沙沉积以及含沙水流的挟沙能力基本达到饱和有关。 相似文献
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为探明降雨条件下沙黄土坡面水流水动力学特性,以流体力学和泥沙运动力学理论为依据,通过5个坡度和5个雨强组合条件下室内模拟降雨试验,系统研究了坡面水流水力参数的变化规律。结果表明,降雨条件下坡面薄层水流雷诺数均小于580,处于层流失稳区;水流流型随雨强和坡度的变化而发生转捩,当坡度较缓、雨强较小时,床面形态处于低能态区和过渡区,床面出现沙纹现象,水流宏观上呈缓流,反之,坡度较陡、雨强较大时,床面由沙纹和沙垄向动平床过渡,宏观上多呈急流;并根据薄层水流阻力组成特点,推导出沙黄土坡面薄层水流阻力计算公式。验证结果表明,该式误差较小,可为坡面侵蚀预报模型的构建提供参考。 相似文献
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火后泥石流是火烧迹地最为严重的次生地质灾害,相对于传统泥石流和震后泥石流,其物源启动模式及致灾机理呈现出特殊性。通过对四川省乡城县仁额拥沟火烧迹地沟道不同时间尺度下的累积侵蚀量统计分析,将火烧迹地物源启动分为3个阶段:坡面侵蚀阶段、高含沙水流沟道侵蚀阶段和泥石流沟道刨蚀阶段,其中面蚀到沟蚀转变所需的汇流面积与斜坡倾斜度和火烈度呈负相关,高含沙水流转变为泥石流后常常造成沟道侵蚀率的激增;火烧后2 a的坡面侵蚀量相当于火烧前10~30 a的侵蚀总量,且主要发生在中度及严重火烧区;火烧区的滑坡发育率远高于未火烧区,但未发现火烈度对滑坡体积有明显影响,其主要受临空面高度影响,并呈幂函数正相关,滑坡物源启动模式为坡脚切坡触发的逐级牵引后退式补给。 相似文献
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黄河数字流域模型是“数字黄河”的重要组成部分,在数字流域模型框架下,以坡面为基本单元,建立了包括植被截留、融雪、地表蓄滞、表层土蓄滞、中层土蓄滞和深层土蓄滞共6层的产流模型.模型在垂向上考虑3层出流:地表超渗产流、表层土侧向渗流和中层土侧向渗流,既反映当前的降水过程,又体现前期降水过程和土壤前期含水量的影响,比较适合黄河流域的产流特点.在坡面产流的基础上,还给出了坡面单元侵蚀产沙公式,用于建立流域产沙数学模型.应用建立的模型,给出了3个计算实例:黄河全流域水量计算、小花区间汛期洪水模拟和多沙粗沙区产沙计算.实践表明:建立的模型基本具备了在黄河全流域进行降雨-径流模拟、侵蚀产沙计算的功能,辅以降雨预报模块则可进行洪水预报. 相似文献
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对当前坡面汇流计算方法的研究进展进行了较为系统的总结与分析,并对坡面汇流的非线性效应以及城市低影响开发中的雨水入渗与蓄集对坡面汇流的控制作用进行了简要分析。从模型简单实用的角度出发,认为以流域时间-面积关系与线性水库相串联的ModClark法等为代表的概念性分布式坡面汇流模型具有良好的发展前景;考虑到基于等流时单元的变动等流时线法在反映雨强非线性影响中存在的问题,认为根据水文响应单元在不同雨强条件下汇流时间的变化,调整其汇流参数以反映坡面汇流的非线性效应,对于流域坡面汇流的分布式模拟更具有实际意义;针对目前低影响开发设施长时间序列大空间尺度的室外降雨径流监测资料普遍较为缺乏的现状,给出了后期应积极选择合适的技术以加强低影响开发性能监测工作的建议。 相似文献
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Veena U. Joshi 《Journal of the Geological Society of India》2014,83(6):613-624
Nearly 4 million hectares of land in India is affected by rill and gully erosion. It is a severe form of soil erosion rendering vast tracts of lands into wastelands giving rise to the formation of badlands. Rate of land degradation through gullying is triggered recently due to the ill-advised landuse practices all over the country. The study area represents one such badland locality along the banks of Pravara river and two of its tributaries in the Deccan trap region, Maharashtra. The area is extensively reclaimed in the last two decades for agricultural practices. The rates in the cross profile changes as well as land lowering were measured with the help of a self fabricated micro-profilometer and erosion pin method. Five first order gullies were monitored using the micro-profilometer. Results of the micro-profilometer technique reveal considerable changes in the cross-sectional areas of individual gullies in this area, which shows the dynamic soil removal mechanism operating in this region. In addition to this, two well developed gully catchments were surveyed using a theodolite and erosion pins were installed in these basins in May 2007. After one year, the exposed pinheads were measured and net gain and net loss in the volume of the sediments were calculated for both the basins. The same practice continued in May 2009. After two years of monitoring the sediment yields were calculated. Average of these two years indicates an annual sediment yield of 1.79 kg/m2 for sample basin 1 and 0.76 kg/m2 for sample basin 2. The calculated yield was compared with the threshold values of soil tolerance limits and it was found that the area has crossed the threshold limit of soil tolerance. 相似文献
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通过整理和分析国内外大量野外调查数据,系统研究了裸露坡耕地壤土土质不同侵蚀沟的断面特征和水力几何形态,并给出了相应的判别标准。结果表明:随坡面侵蚀沟逐步发展,宽深比参数ζ逐渐减小,细沟、浅沟、切沟和冲沟适宜的ζ范围分别为5~17、2~5、0.4~1.8和0.1~0.6;同一侵蚀沟条件下,壤土类型对ζ值也有影响。土壤质地越细,ζ值越小。不同侵蚀沟水力几何形态指数也不相同,细沟的形态指数β1、β2和β3分别为0.3、0.4和0.3,浅沟和切沟为0.4、0.4和0.2,冲沟为0.5、0.4和0.1。验证结果表明给出的判别标准可以用来界定不同侵蚀沟类型。 相似文献
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在坡面土壤侵蚀输沙计算中,可选用的输沙能力模式较多,但这些模式多运用于恒定输沙,在非恒定输沙中运用不多。建立了坡面土壤侵蚀非恒定输沙数学模型,模型中的输沙能力运用水流切应力、水流功率、单位水流功率3种模式,对模型过程采用有限差分格式离散求解。根据实测水沙资料进行模型参数率定,运用3种输沙能力模式于不同降雨强度、不同坡度的非恒定坡面输沙过程中。结果表明:在坡面非恒定输沙计算中,不同输沙能力模式对计算结果有明显影响,在降雨强度较小时,单位水流功率模式结果较其他两个模式为好,而在雨强较大时,切应力模式计算结果较好。 相似文献
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本文提出华南红土区水土流失的重大问题。水土流失的方式有:(1)坡面散流侵蚀;(2)暴流冲沟侵蚀。按风化分层出露情况可将花岗岩丘陵区的水土流失分为德庆崩岗型和五华沟谷型两大类。当风化层底部砾石层出露时,则地表呈“石蛋地形”,可用这种地表形态结构作为水土流失划分的指标。 相似文献
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Soil erosion and management recommendations at three State Vehicular Recreation areas,California 总被引：3，自引：0，他引：3
Off-road vehicle (ORV) impact on the landscape includes the destruction of protective vegetative cover, soil compaction, and
increased runoff followed by increased erosion. An investigation of three State Vehicular Recreation Areas (SVRAs) in arid
regions of California have documented 10-to 25-fold increases in sediment yield relative to nearby undisturbed basins. Soil
texture and slope length are the dominant factors controlling soil erodibility in these areas. Organic carbon content of the
soil exposed in hillclimb gullies was comparable to C horizon values of undisturbed soil profiles demonstrating a significant
(70%) loss of soil fertility due to accelerated erosion.
Soil erosion can be minimized and lifespan of these recreational areas prolonged by initiating and enforcing some critical
management policies, including careful control over location and length of hillclimb, rotating use areas such that rehabilitation
or revegetation is feasible, and seasonal use restrictions. 相似文献
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Effects of gully erosion and gully filling on soil depth and crop production in the black soil region, northeast China 总被引：5，自引：0，他引：5
Honghu Liu Tianyu Zhang Baoyuan Liu Gang Liu G. V. Wilson 《Environmental Earth Sciences》2013,68(6):1723-1732
Gully erosion is a very serious problem in the black soil region of northeast China. Gully filling is often adopted for controlling gully erosion by local farmers and thus causes more serious soil erosion. In this study an ephemeral gully (EG, 74 m) and a classical gully (CG, 52 m) connected at the gully’s headcut were selected as the study site. Two comparisons were made to explore the effects of gully erosion and the subsequent gully filling on soil depth and soybean yield: (1) soil depth between 81 sample points in the study site and 11 reference points along the same slope with the gully; (2) soybean yield between 81 sample points in the study site and 30 baseline locations near the study site. The results indicated that gully erosion caused the reduction of soil depth and soybean yield. Although filling gullies with soil from adjacent areas seemed to be an expedient way to remediate the gullies, it resulted in substantial soybean yield reduction. Gully erosion reduced the soil depth and soybean yield in 74.4 and 83.9 % of the study site, respectively. The soybean yield reduction ratio was 34.5 % for the whole study site and 2.6 % for the black soil region. Soil depth was the most important soil property indicator to reduce yield. Every 1 cm decrease in soil depth in the areas adjacent to gullies due to infilling activities resulted in a 2 % decrease in yield. More significant was the deposition of sediment from gully erosion, which completely eliminated soybean yield. Currently, effective soil and water conservation measures are not known and adopted by local farmers extensively. In the future, once some measures for preventing soil erosion, in particular gully erosion, were proved effective, these technologies should be disseminated among local farmers. 相似文献
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在明渠中开展不同水流条件下低强度均匀沙平衡输沙试验,基于灰度相减方法分析整个床面推移质运动特征,以探寻紊流结构与推移质运动之间的作用机理。结果表明:①受水槽横向方向水流强度分布特征影响,推移质运动概率从水槽中线到两侧壁逐渐变小,且基本呈对称分布;②在紊流相干结构作用下,推移质床面在紊流低速条带区形成凸槽,高速条带区形成凹槽,推移质运动概率沿水槽横向方向存在高低相间的带状分区;③随摩阻雷诺数增大,相邻两推移质运动高概率区域的间距值变化范围为0.13~0.24倍水槽宽度,其值随摩阻雷诺数增大而增大;④不同水流条件下,推移质运动高概率区域间距值约为水深的2倍,这与流向涡模型吻合,表明流向涡是诱导床面出现凹凸相间形态的重要因素。 相似文献
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The influence of shallow landslides on sediment supply: A flume-based investigation using sandy soil 总被引：1，自引：0，他引：1
The impact of rainfall-induced shallow landslides on hillslope sediment discharge is not well understood. This paper reports experimental measurements of sediment discharge after water-induced shallow landslides are triggered on sandy soil in a flume under simulated rainfall. The principal aim of the research was to investigate how varying soil depth affects the location and occurrence of shallow slope failures, as well as how it affects sediment yields downslope. Four experiments were conducted using the same sandy soil and a 30° and 10° compound slope configuration under average rainfall intensity of 50 mm h− 1 for up to 390 min. Soil depths were set to 200, 300, 400 and 500 mm. Engineering and geotechnical properties of the soil were examined. Sediment discharge and runoff were collected from the flume outlet at 15 minute intervals. Changes in the soil slope profiles after landslides and soil physical properties resulted from soil armouring, under continuous rainfall were also recorded. Results showed that sediment yields at the flume outlet, before landslides occurred, were very low and limited to the finer soil particles as would be expected for a sandy soil. However subsequent variations in sediment discharge were strongly related to failure events and their proximity to the outlet. Sediment yield was also affected by the original soil depth; the greater the depth, the higher the sediment yields. Post-failure reductions in sediment discharge were observed and attributed to post-failure slope stabilization under continuing rainfall and extensive soil armouring near the flume outlet. The results provide a clear linkage between landslides and sediment discharge due to hydrological processes occurring in the hillslope. This knowledge is being used to develop a model to predict sediment discharges from hillslopes following shallow landslide events. 相似文献