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1.
This paper describes a prototype of a portable rainfall simulator that can simulate a wide range of rainfall intensities with a kinetic energy similar to that of natural rainfall and, more innovatively, provide simultaneous or independent simulations of rainfall and overland flow at the microplot scale (0.70 m2 ). The design of the rotating shutter disc makes possible a wide range of rainfall intensities, from 30 to 155 mm/h without changing nozzle type or working pressure. Overland flow intensity can be adjusted from 94 to 573 mm/h depending on nozzle type and working pressure. The flow is applied on the upper side of the experimental plot. The Christiansen coefficient of uniformity of the simulated rainfall varied between 81.4 and 85.1%, and the calculated kinetic energy was >90% the kinetic energy of corresponding natural rain. Special attention was paid to portability. Stainless steel was used whenever possible and the equipment was constructed in modules so that it could easily be dismantled and carried by two people. A telescopic-type frame allows operation on sloping ground. 相似文献
2.
人工模拟降雨装置的设计及其参数率定 总被引：6，自引：0，他引：6
[目的]针对水环境领域中地表径流的水质研究所需的降雨特点,设计了一种人工模拟降雨装置。[方法]该模拟降雨装置采用3个规格不同的喷嘴式喷头,利用不同喷头的启闭与组合实现不同雨强的模拟。[结果]经率定,此装置降雨强度可达0.3~2.0mm/min,在此范围内降雨均匀系数均在85%以上,雨滴中数直径的范围为1.09~2.25mm,最大雨滴直径不超过6mm,雨滴终点速度可达到2~2.9mm/s。[结论]该装置模拟降雨与天然降雨的相似程度较高,可用于模拟真实的降雨情况。 相似文献
3.
《Land Degradation \u0026amp; Development》2017,28(4):1320-1328
Land degradation processes start with accelerated runoff and sediment delivery. In this study, rainfall‐runoff induced sediment transport is investigated using data from an indoor laboratory experimental setup consisting of a rainfall simulator and an erosion flume. The data are analysed to develop empirical models using sediment discharge, slope, flow discharge, rainfall intensity and sediment size. Fine and medium sands are considered as bare soil in experiments. Four rainfall intensities (45, 65, 85 and 105 mm h−1) are applied with combinations of lateral and longitudinal slopes of 5%, 10%, 15% and 20%. Eighty experiments are conducted. Flow is measured, and sediment within flow is separated and weighted. Experimental data are used for developing empirical models through multiple regression with parameters optimized by genetic algorithm. Results show that slope is the main contributing variable to the sediment transport over hillslopes. Accommodating variables among slope, rainfall intensity, flow discharge and median diameter of sediment as independent variables, one‐variable, two‐variable and four‐variable models are developed considering also that higher number of parameters increases the performance of the model with higher cost of parameterization. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
4.
由于人工模拟降雨可以解决天然降雨耗时长、成本高以及难以取得精准控制数据等问题,越来越多的学者使用该方法进行科学研究。通过降雨量测量和计算分析方法,测定了Veejet80150喷头降雨特征参数,评价了改进后槽式下喷模拟降雨机的降雨均匀性。结果表明:Veejet80150喷头降雨面积为矩形,且随喷头高度增加而增加,中心点降雨强度随高度增加而减小,并从中心点向外呈规律性减小,便于多喷头组合,获得空间均匀降雨。多喷头组合降雨时,2.5 m高度下的降雨均匀系数在0.88~0.90范围内;4 m高度下的降雨均匀系数在0.94~0.95范围内,该降雨机均匀性好,喷头高度大于2.5 m时可满足试验要求。 相似文献
5.
《Land Degradation \u0026amp; Development》2017,28(5):1615-1625
Rill is a major type of erosion on upland slopes. Continuous rainfall is commonly used in laboratory studies on rill erosion despite the fact the rainfall was often discontinuous in the field; this is particularly true in the Chinese Loess Plateau. This study compares rill erosion under continuous and intermittent rainfalls by using laboratory experiments. The experiments include two rainfall‐intensity treatments (90 and 120 mm h−1) and two rainfall‐pattern treatments (continuous and intermittent). The results indicate that rill formation had a significant effect on runoff and sediment concentration. For continuous and intermittent rainfall at the rainfall intensity of 90 mm h−1, the mean sediment concentrations were 1·91 and 1·73 times after rill initiation than those before rill initiation, respectively, and the rill erosion accounted for 75·5% and 77·7% of runoff duration, respectively. For continuous and intermittent rainfall at the rainfall intensity of 120 mm h−1, the mean sediment concentrations after rill initiation were 1·38 and 1·32 times that those before rill initiation, respectively, and the rill erosion represented 88·7% and 78·8% of the total runoff duration, respectively. We observed sediment sorting under all treatments; however, the low rainfall intensity boosted but the high rainfall intensity lowered the clay fraction; in contrast, the sorting remained roughly the same between the rainfall‐pattern treatments. The runoff velocity also affected the sediment sorting. Our empirical results indicated the important significance of the rainfall intermittence in predicting rill erosion. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
6.
能量相似是降雨模拟的基本原则。通过对雨滴粒径、雨滴击溅速度、降雨均匀度等能量相似要素的分析和探讨,提出实现降雨模拟能量相似的重要手段,即在降雨高度、雨滴发生器等条件不变的情况下,通过调节雨强来实现降雨能量的相似;通过加大供水压力等手段可提高降雨动能,所以在降雨模拟实践中,降雨高度不一定需要达到使所有粒径的雨滴均达到终速所需的高度。 相似文献
7.
坡面径流含沙量随雨强和坡长的动态过程 总被引：1，自引：1，他引：1
坡面径流的含沙特征是研究坡面侵蚀产沙的重要内容。为了研究坡面径流含沙特征及动态过程,揭示坡面径流含沙量随雨强和坡长的复合关系。采用人工模拟降雨的方式,通过不同坡长和雨强的组合试验,基于跨雨强和跨坡长的综合性分析思路,对特定坡度(20°)下,5个坡长(1,2,3,4,5m)13个降雨强度的试验监测数据进行了分析。结果表明:(1)坡长不同,含沙量与雨强的相关性不同,以2,3,4m坡长含沙量随雨强增加的规律性最明显,5m坡长的相关性最差,1m坡长的直线相关性较好,但增长斜率很小,由此可推得,研究坡面径流含沙量随雨强变化时,以2~4m坡长的试验槽较为适宜;(2)含沙量随产流历时总体上呈现出波动递减的趋势。含沙量波动特征值在2~4m坡长范围内波动性小而波动频率大,在1,5m坡长的波动性大但频率小。坡面径流含沙量变化的频率远大于河川径流含沙量的变化频率,即稳定性较差;(3)含沙量与主要水文要素和水力学特征参数的拟合都呈现出极显著相关性,流速、流量和剪切力是影响含沙量波动的重要因素。 相似文献
8.
J. Fernández-Gálvez E. Barahona A. Iriarte M. D. Mingorance 《Water, air, and soil pollution》2008,191(1-4):257-264
Elevated concentrations of trace metals in soil can increase the risk of pollution to ecosystems and human health. This cannot be predicted solely from the total and/or extracted concentration of metals from soil samples, as movement of trace elements to the groundwater is also a result of the flow solution through the vadose zone. The rate at which trace elements move are not usually directly measurable, and thus it must be estimated taking into account water transport through the soil. Therefore, a field portable drop-former rainfall simulator has been designed and used to study trace-element mobility in small field plots. The rainfall simulator permits a wide range of variation in rainfall intensities and provides a homogeneous distribution of the simulated rain in a 0.25 m2 plot with low cost per data collected and short time. Performance of the rainfall simulator has been evaluated and a preliminary assessment of the amount of pollutants present in the soil (As, Cu and Zn) that can reach groundwater via soil drainage is made by combining rainfall-simulation experiments with infiltration estimates based on a stochastic model of the local climate. The study was conducted in soils affected by the Aznalcóllar toxic spill in the Guadiamar river basin (Spain). Infiltration experiments reveal that the trace elements could be classified according to their mobility as As < Cu < Zn. The presence of high gravel content below this depth increased the amount of drainage and therefore the risk of groundwater pollution, especially with Zn, which was found below 50 cm depth. 相似文献
9.
Sílvia C. P. Carvalho Joo L. M. P. de Lima M. Isabel P. de Lima 《Land Degradation \u0026amp; Development》2016,27(4):1295-1302
Rainfall simulators are an important tool in studying soil erosion, which is a key process contributing to land degradation. The kinetic energy of simulated rain is central to these studies and it is used as an indicator of the raindrops' ability to detach particles from the soil surface. The main purpose of this experimental work was to explore the usefulness of incorporating meshes underneath pressurised nozzles' rain simulators that intercept the drops sprayed out by the nozzles and change the simulated rain characteristics, namely by increasing the rainfall kinetic energy. The laboratory experiments included testing four types of spray nozzles (discharge from 2·3 to 11·9 L min−1), combined with a high‐density polyethylene mesh (square aperture of 20 mm). The effect of the mesh was studied for three vertical distances between the nozzle and the mesh (0·20, 0·40 and 0·60 m). A laser disdrometer was used to measure the diameter and fall speed of the simulated raindrops. For the mesh‐free simulations, the nozzles produced drops having on average a mean equivalent diameter of around 0·6 mm and a mean fall speed of about 1·5 m s−1. The mesh increased the formation of bigger drops (>2·5 mm) and, consequently, increased the rainfall kinetic energy of the simulated rain; the magnitude of this increase varied with the spray produced by the nozzles. Results show that meshes can be useful for increasing the kinetic energy of the rainfall simulated by nozzles within soil erosion studies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
为研究嵌套砾石红壤坡面的壤中流动态过程及降雨产流分配,以红壤缓坡(10°)和陡坡(25°)坡面为研究对象,采用室内人工模拟降雨的方法研究不同降雨强度(60,90,120 mm/h)和不同砾石含量(0,10%,20%,30%)条件下壤中流的初始产流时间、产流速率和径流过程。结果表明:(1)不同含量砾石嵌套红壤坡面壤中流初始产流时间在雨强60 mm/h时接近15 min,在雨强90,120 mm/h时差别较大;雨强从60 mm/h增大到120 mm/h,不同含量砾石嵌套红壤坡面壤中流量和产流速率基本上表现为降低,其中25°嵌套20%和30%砾石坡面的壤中流产流速率均值分别下降86.7%和89.0%,雨强120 mm/h时壤中流峰值仅为60 mm/h条件下的10.7%和10.2%。(2)10°和25°各试验坡面,雨强60 mm/h时地表径流所占比例为8.0%~66.3%,雨强120 mm/h时地表径流所占比例为76.1%~93.5%,地表径流所占比例均随雨强的增大而提高32.8%~1 009.4%;雨强60 mm/h时壤中流所占比例为7.3%~30.0%,雨强120 mm/h时壤中流所占比例为1.1%~9.6%,壤中流所占比例随雨强增大而减小46.1%~93.9%。(3)回归结果显示,壤中流峰值流量Ip、壤中流系数It、壤中流消退速率K和降雨强度、砾石含量的二元线性回归效果都达到了显著水平(P<0.05);坡度10°时,降雨强度和砾石含量对壤中流过程参数所起的作用是相反的,而坡度25°时,砾石含量和降雨强度对壤中流各参数的作用相同。 相似文献
11.
Revegetation of road cuts and fills is intended to stabilize those drastically disturbed areas so that sediment is not transported to adjacent waterways. Sediment has resulted in water quality degradation, an extremely critical issue in the Lake Tahoe Basin. Many revegetation efforts in this semiarid, subalpine environment have resulted in low levels of plant cover, thus failing to meet project goals. Further, no adequate physical method of assessing project effectiveness has been developed, relative to runoff or sediment movement. This paper describes the use of a portable rainfall simulator (RS) to conduct a preliminary assessment of the effectiveness of a variety of erosion‐control treatments and treatment effects on hydrologic parameters and erosion. The particular goal of this paper is to determine whether the RS method can measure revegetation treatment effects on infiltration and erosion. The RS‐plot studies were used to determine slope, cover (mulch and vegetation) and surface roughness effects on infiltration, runoff and erosion rates at several roadcuts across the basin. A rainfall rate of ≈60 mm h−1, approximating the 100‐yr, 15‐min design storm, was applied over replicated 0·64 m2 plots in each treatment type and over bare‐soil plots for comparison. Simulated rainfall had a mean drop size of ≈2·1 mm and approximately 70% of ‘natural’ kinetic energy. Measured parameters included time to runoff, infiltration, runoff/infiltration rate, sediment discharge rate and average sediment concentration as well as analysis of total Kjeldahl nitrogen (TKN) and dissolved phosphorus (TDP) from filtered (0·45 μm) runoff samples. Runoff rates, sediment concentrations and yields were greater from volcanic soils as compared to that from granitic soils for nearly all cover conditions. For example, bare soil sediment yields from volcanic soils ranged from 2–12 as compared to 0·3–3 g m−2 mm−1 for granitic soils. Pine‐needle mulch cover treatments substantially reduced sediment yields from all plots. Plot microtopography or roughness and cross‐slope had no effect on sediment concentrations in runoff or sediment yield. RS measurements showed discernible differences in runoff, infiltration, and sediment yields between treatments. Runoff nutrient concentrations were not distinguishable from that in the rainwater used. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
12.
嘉陵江流域降雨侵蚀力时空变化分析 总被引：3，自引：1，他引：2
降雨侵蚀力是降雨引起土壤侵蚀的潜在能力,对预测土壤侵蚀量具有重要意义。对嘉陵江流域12个气象站的日降雨量资料,利用章文波日降雨侵蚀力模型估算流域的降雨侵蚀力。结果表明:嘉陵江流域降雨侵蚀力的空间变异与降雨量的空间分布趋势基本一致,由东南向西北递减,变化于800～9 000MJ.mm/(hm2.h.a)之间;流域内降雨侵蚀力年际变率Cv在0.346～0.493之间,除平武站呈显著减少外并无显著变化趋势;年内降雨侵蚀力随季节变化,夏秋季降雨侵蚀力较大,冬春季降雨侵蚀力较小。降雨侵蚀力年内集中度高,6—9月份的降雨侵蚀力占全年降雨侵蚀力的80%以上。近50a降雨侵蚀力存在35a,21a的主周期变化,且对应不同的丰枯状态。研究结果表明,虽然年降雨侵蚀力无明显变化,但年内却相对集中于夏秋两季,因此仍要做好汛期的水土流失等灾害的防治。 相似文献
13.
槽式摆喷头下喷式人工模拟降雨机的雨强及其空间分布率定 总被引：11，自引：0，他引：11
人工模拟降雨机由于不受时间和空间的限制而成为研究降雨影响入渗、产流、冲刷、侵蚀产沙等动力学机理的重要试验手段。为解决我国目前降雨机模拟降雨特性与天然降雨特性相差较大的问题,设计了槽式摆喷头下喷式人工模拟降雨机。通过试验分别率定了该降雨机单喷头降雨雨强和多喷头组合降雨雨强的相关参数．以便为用户应用提供技术指标。该降雨装置在2．5m的高度下模拟的雨强范围为11．3～132．5mm／h。单喷头受雨面呈矩形,沿喷头摆动方向2．0m宽,垂直摆动方向2.7m长,受雨面积为5．4m^2。为形成均匀的雨强空间分布,需进行多喷头组合。组合实验表明,沿摆动方向的相邻喷头最佳距离为1．1m,沿垂直摆动方向的相邻喷头最佳距离为1.5～1．6m,组合后的雨强空间均匀性系数达到0．89以上。目前测试雨机的单机由5个喷头组成,相邻喷头为摆动方向,距离1.1m。用户可根据实验面积自行选择争机喷头数量和雨机数量．相邻雨机喷头间的水平距离建议为1．5～1．6m。 相似文献
14.
洱海弥苴河流域降雨侵蚀力特征研究 总被引：3，自引：0，他引：3
收集了洱海弥苴河流域内5个雨量站1997—2006年共10年的逐日降雨量及洱源县气象站1957—2000年共44年的逐年降雨量资料,对比分析了不同降雨侵蚀力估算方法的适用性,在此基础上对1997—2006年间弥苴河流域降雨侵蚀力的年内和空间分布特征及1957—2000年间降雨侵蚀力的长期年际变化特征进行了较为详细的探讨。研究结果表明:RUSLE模型中采用的降雨侵蚀力估算方法,对采用不同降雨资料所估算的年均降雨侵蚀力结果均具有较高的精度;1997—2006年间弥苴河流域年均降雨侵蚀力R值为1 941.8 M J.mm/(hm2.h.a),并且集中分布于6—10月,其中以7—9月的集中程度最高;1997—2006年10年内流域年均降雨侵蚀力的空间分布呈现北部→西南部→中部→东南部依次降低的特点;1957—2000年间流域年均降雨侵蚀力R值为2 352.1 M J.mm/(hm2.h.a),逐年降雨侵蚀力大致呈现出10年左右的周期性变化。 相似文献
15.
黄土高原是我国植被破坏与水土流失最为严重的地区。本文基于室内坡地降雨实验,分析了塿土坡面降雨入渗补给系数的变化,对比了不同雨强影响下径流泥沙含量和累积泥沙含量的时间变化趋势,并将侵蚀与入渗结合,分析了同时段产沙量和入渗率的变化关系,研究表明:入渗补给系数随雨强增大而逐渐减小,两者可描述为线性关系,雨强越小,入渗补给系数越高;降雨初始产沙值最大,在产沙10 min内变缓。雨强大的,初始产沙量和稳定沙量都稍大,但总体差异不大,产沙量分布曲线形状与入渗率曲线极为相似;不同雨强下累积泥沙量与降雨历时之间存在明显的幂函数关系,且幂函数的指数部分基本随降雨雨强增加而逐渐增加;不同雨强下入渗率和累积泥沙量的变化趋势相反,当累积泥沙量增加,相应的土壤入渗率减小,两者变化趋势随雨强增大而趋于明显。 相似文献
16.
泾河南小河沟流域自然降雨特性 总被引：2，自引：0，他引：2
采用德国HSC-OTT Persivel32激光雨滴谱探测仪监测南小河沟流域自然降雨的雨滴谱,分析不同雨型自然降雨雨滴特征及其分布规律,并分析了降雨特性各要素间的相互关系。结果表明:(1)该区自然降雨雨滴直径集中在0.3~1.5mm,与黄土高原利用传统的滤纸色斑法测定结果基本一致,但略小于东北和闽南地区。当雨强I10mm/h时,雨滴中数直径随雨强的增大而增大;当I≥10mm/h时,雨滴中数直径骤然下降,这在一定程度上和雨强增大后大雨滴破裂有关。该地区雨谱随雨强的变化可用Best分布拟合。(2)普通型降雨雨滴数量随直径的分布曲线较平缓,其动能与雨强呈线性相关;而短阵型降雨的雨滴数量随直径的分布曲线较陡峭,其动能与雨强呈幂函数关系。两种雨型的降雨动能均随雨强的增大而增大,但短阵型降雨动能增大的更快,因此短阵型降雨的侵蚀力更大。 相似文献
17.
卧龙地区针叶林及亚高山灌丛对降雨的雨滴谱及能量的影响 总被引：6，自引：2，他引：6
在运用色斑法研究岷江冷杉及川滇高山栎灌丛林下的雨滴滴谱及降雨动能的基础上,探讨了上述两个生态系统林冠雨谱特征及降雨动能削减特征,比较了3种雨滴终速计算方法的适用性。结果表明:两种生态系统树冠层对降雨动能的改变作用有一定差异,灌丛林下的降雨动能一般小于林外降雨动能,而且雨强增大时灌从对动能的削减作用更加明显一些;但针叶林下的降雨动能却显著高于林外降雨动能,雨强增大时林下的降雨动能比有下降的趋势。在计算雨滴终速时,比较好的计算方法为Beard经验公式法,沙玉清公式(及修正的牛顿公式)法。 相似文献
18.
SR型野外人工模拟降雨装置 总被引：34，自引：3，他引：34
SR型人工降雨装置是一种多喷头、多单元组合式的间歇降雨装置.选用目前国内外较理想的喷头,在喷头处辅以可改变喷头降水方式的机械传动装置,以间歇方式降雨来满足其降雨强度,雨滴直径大小及其分布与自然降雨相似.每个单元的有效降雨面积为2m×5m;如果4个单元组合成,其长度可增加4倍,有效降雨面积即2m×20m.装置采用轻型铝合金材料制成,结构简单,易于安装拆卸,适用于野外工作. 相似文献
19.
在人工降雨条件下,采用色斑法对黄土地区4个主要树种幼树进行林冠降雨观测。结合AutoCAD、Excel数据处理软件,在0．1mm径级下分析不同树种的林冠降雨特性,并对比研究林外降雨和不同树种的林下降雨动能。结果表明：1）不同树种林冠降雨雨谱基本不受空旷地降雨强度影响;2）用正态分布函数和类卡方分布函数对林冠降雨雨谱描述和分析容易失真,应寻求更好的数学形式对林冠降雨雨谱进行表达;3）林冠降雨雨滴直径—体积分布密度图是双峰曲线,表明Best函数同样未能对林冠降雨大雨滴作出准确描述,而利用多项式函数直接表达累积体积效果更好;4）不同树种单位水体（1L）的林冠降雨动能大小为侧柏（28．18J）〉油松（26．74J）〉元宝枫（25．75J）〉刺槐（20．07J）,此结论也为在充分降雨条件下判断植被冠层是否增加了降雨动能提供了可比条件。 相似文献
20.
为研究在长时间降雨侵蚀过程中北京褐土坡面侵蚀特征及其水动力学机制,通过室内人工模拟降雨试验,分别在60,90 mm/h雨强下对褐土坡面进行连续10场次降雨试验,探讨了坡面侵蚀过程中的产流产沙特征及其与水动力学参数间的关系。结果表明:(1)在雨强及次降雨量较一致的条件下,随降雨场次增加坡面次降雨产流量变动较小,而次降雨产沙量变化较大,60,90 mm/h雨强下次降雨产沙量的变异系数为23.94%和59.88%,且第10场降雨的产沙量仅为第1场降雨的59.74%和22.28%;(2)连续降雨条件下,平均次降雨产沙速率随雨强增大而增大,径流含沙量随降雨时间呈幂函数下降趋势;(3)受褐土坡面细沟形态变化和土壤粗化的影响,60,90 mm/h雨强下坡面径流平均流速分别随降雨时间呈指数函数和幂函数下降趋势,弗劳德数亦表现出相同趋势;坡面径流阻力系数随降雨历时均呈对数函数增加;(4)长时间降雨侵蚀条件下径流含沙量与平均流速、弗劳德数、阻力系数、径流功率相关关系极显著,其中平均流速是径流含沙量变化过程中与其关系最为密切的水动力学参数,径流含沙量的变化深刻受到坡面径流平均流速的动力作用过程影响。 相似文献