坡度对降雨溅蚀影响的研究

利用可以分别收集不同方向溅蚀土样的土槽装置,选取9个坡度(5°~45°),采用北京的普通褐土,借助人工模拟降雨手段研究了降雨溅蚀的发生过程及溅蚀量与坡度的关系。结果表明,随着坡度的不同,各方向的溅蚀过程呈现三种形式:(1)产流前溅蚀率较小,产流后迅速达到峰值,之后逐渐减小并逐渐达到稳定,峰值与稳定溅蚀率相差2倍以上;(2)产流前溅蚀率最大,产流后迅速减小并趋于稳定;(3)整个降雨过程中没有明显起伏。各个坡度下,次降雨溅蚀量均为上坡最小,下坡最大。上坡和侧坡溅蚀量与坡度成负相关,可分别用直线和指数函数拟合。下坡溅蚀量、溅蚀总分散量和溅蚀净搬运量均随着坡度的增大而先增大后减小,且为线性关系,临界坡度为35°。本研究将有助于深入理解降雨溅蚀侵蚀机理,并可为布设水土保持措施提供理论依据。     

丹江口库区坡耕地不同作物对土壤溅蚀的影响

选取位于丹江口库区的代表性坡耕地,通过野外调查与室内分析,研究种植不同作物(黄姜、红薯、芝麻与玉米)对土壤溅蚀的影响,同时探讨土壤溅蚀与作物株高、覆盖度及其土壤含水量、温度的相关性。结果表明:在作物生长前期,各处理土壤溅蚀差异不显著;在生长盛期,种植作物显著降低土壤溅蚀,其中相对于对照处理,黄姜处理降低幅度最小,芝麻与玉米次之,红薯则最大。相关分析表明,土壤溅蚀与作物覆盖度、土壤含水量及土温呈显著的一元二次曲线相关。因此,种植作物改变了坡耕地局部空间格局,使降雨发生空间再分布。     

Effect of slope borders in reducing splash erosion during sediment transport by rain-induced overland flow

Splash erosion plays a vital role in the loss of eroded materials. Unlike those in slope central areas, laterally ejected splashed materials in slope border areas cannot be replenished easily because slope edges prevent splash erosion particles from entering the slope. Thus, splashed materials in slope border areas are less than those in slope central areas because of the lack of source areas for splash-eroded materials. However, this phenomenon, called the slope border effect, has received minimal attention by researchers. The partially missing splash erosion induced by the slope border effect on sediment transport was investigated to understand the slope erosion mechanism further in this paper. A modified soil pan divided into four areas, namely, central erosion test area (length = 100 cm, width = 35 cm, depth = 45 cm), border erosion test area (length = 100 cm, width = 35 cm, depth = 45 cm), splash compensate border area (length = 110 cm, width = 30 cm, depth = 45 cm) and splash collection area (length = 100 cm, width = 2.5 cm, depth = 45 cm) was used to monitor diffusion and splash erosion under simulated rainfall. Results showed that the splash detachment rate increased with the increase in slope but initially decreased and then increased with the increase in rainfall intensity. The runoff rate and diffuse erosion rates for complete splash erosion (SE) treatments were higher than those without partial splash erosion (SE_L). Under low rainfall erosive power and runoff transport capacity (e.g., 5° slope and 60 mm h⁻¹), the transported clay in SE treatments was approximately 2% more than that in SE_L treatments. This amount changed to more than 2% sand under high rainfall and runoff erosive power. However, the mass fraction accounted for by silt particles in the sediments of the SE_L treatments was more than that in the SE treatments. Thus, the partially missing splash erosion can weaken the selective transport ability of runoff for sediments. The effect of missing partial splash erosion on diffuse erosion was enhanced with an increase in erosive power. The results of our paper will provide insights into the effect of the boundary effect zone of slope on soil erosion and its related mechanisms.     

雨滴击溅对耕作层土壤团聚体粒径分布的影响

为研究不同雨滴直径的降雨对耕作层团聚体的破碎及其粒径分布特征的影响,该文选取4个雨滴直径(2.67~3.79 mm)对耕层土壤(0~20 cm)团聚体进行雨滴击溅试验,每次试验各滴5 000滴,每1 000滴收集1次溅蚀团聚体。结果表明:1)所有收集次序中雨滴直径3.79 mm溅蚀量最大,累积雨滴数为2 000、3 000和4 000时,溅蚀量与雨滴直径均呈显著的指数函数关系。2)各雨滴直径的溅蚀量随粒径减小呈增大-减小-增大趋势,2 mm粒径的溅蚀量几乎为0,0.053 mm粒径的溅蚀量随雨滴直径增大而增大。3)相同雨滴直径不同累积雨滴数之间平均重量直径值差异不显著,相同累积雨滴数不同雨滴直径之间平均重量直径值差异不显著(P0.05)。4)不同雨滴直径溅蚀团聚体富集率随粒径变化一致,1 mm粒径溅蚀量团聚体富集率值接近0,0.053~1 mm粒径团聚体富集,1 mm粒径团聚体主要破碎成0.053~1 mm粒径团聚体,且粒级越小,富集率越高。研究可为黄土高原地区水土保持提供理论依据。     

Estimation of soil splash detachment rates on the forest floor of an unmanaged Japanese cypress plantation based on field measurements of throughfall drop sizes and velocities

To study and model the interrill erosion process in an unmanaged Japanese cypress (Chamaecyparis obtusa) plantation, soil splash detachment rates were estimated based on the quantification of throughfall raindrop indices. Throughfall drops and soil splash detachment were simultaneously observed in the field, and observed data were compared with estimates produced by previous models. Observations took place over five months in 2005, during six observation periods. Raindrop indices of kinetic energy (KE), momentum (M), and momentum multiplied by the drop diameter (MD) were calculated from drop diameters and velocities. The median volume diameter of 1.99 mm for the overall observation period was well bounded by those from other Japanese cypress plantations. Throughfall consisted of large drops, generated as drips, exceeding 3 mm in diameter. The fall height was insufficient for the drops to attain terminal velocity, with 91% of the drops reaching less than 90% terminal velocity. The observed throughfall raindrop indices had strong correlation with throughfall rainfall intensity, even though throughfall raindrops occurred in seven rainfall events with different meteorological conditions. The values of observed KE and M were lower than previous model-derived estimations. Earlier models tended to overestimate throughfall KE and M, partly because the expected velocity was greater than that observed, and partly because they did not consider the effect of the splash water component during throughfall. The splash detachment rate in forests was weakly correlated with the total-amount raindrop indices but strongly correlated with the maximum value of raindrop indices over a short time scale such as 1 h. This result indicates that continuous and concentrated raindrop impacts over a short time duration cause splash detachment in the forest floor. Development of a comprehensive model of the process of forest floor soil surface erosion requires more detailed measurement of actual throughfall drops.     

前期土壤含水率对红壤团聚体稳定性及溅蚀的影响

为了探究前期含水率对南方红壤团聚体稳定性及溅蚀的影响,选取泥质页岩和第四纪红黏土发育的4个典型红壤为研究对象,就5个前期含水率(3%、5%、10%、15%、20%)条件下3~5 mm团聚体水稳定性特征及其与溅蚀的关系进行了初步的探讨。结果表明,消散作用是团聚体破碎最有效的机制,土壤前期含水率越大,团聚体破碎程度越小。随着前期含水率的升高,泥质页岩发育的2种红壤水稳性团聚体平均质量直径(MWDwa)显著增大;第四纪红黏土发育的2种红壤水稳性团聚体平均质量直径(MWDwa)先增大后减小,拐点出现在含水率为15%条件下。泥质页岩发育2种红壤溅蚀量随前期含水率的升高显著减小;第四纪红黏土发育2种红壤溅蚀量随前期含水率的升高呈现先减小后增大的趋势,在含水率为15%时达到最小。团聚体水稳性较高的土样,溅蚀粒径分布呈双峰曲线分布,主要分布1~0.5和0.05 mm范围内,且前期含水率越高,0.05 mm溅蚀颗粒含量越大;而团聚体水稳定性较差的土样,除前期含水率为20%外,溅蚀粒径分布呈单峰曲线分布,主要分布在0.25~1mm。该结果为红壤区农业水土工程及机侵蚀机理研究提供一定的参考,对完善坡面水蚀模型具有一定的参考价值。     

基于齿面移动法的齿轮飞溅润滑性能数值分析与验证

由于齿轮传动系统飞溅润滑过程中润滑油流动的复杂性,近年来数值仿真分析方法已逐渐成为评价飞溅润滑性能的重要手段。为解决齿轮飞溅润滑数值建模过程中由于啮合位置间隙太小而带来网格划分困难的问题,该文提出了采用齿面移动法对齿轮进行处理,即在保留所有轮齿和不改变齿轮安装位置的基础上,通过改变轮齿厚度来增大啮合区域间隙,以便于流体域网格划分。该文对不同处理方法获得的飞溅润滑仿真结果进行了对比分析,并结合试验数据,说明了齿面移动法相对于现有文献中的齿轮建模处理方法获得的润滑油飞溅效果更符合实际情况,搅油功耗计算结果误差在8%以内,且工程适用性更好。该研究为进一步分析车辆变速箱、驱动桥等齿轮传动系统的润滑状况提供了参考。     

降雨强度和坡度对东北黑土区顺坡垄体溅蚀特征的影响

坡耕地溅蚀特征研究可揭示和反映溅蚀的发生和发展机理,而以往研究大多在无垄作坡面进行,较少涉及顺坡垄体。为此,该研究基于野外人工模拟降雨试验,设计3个降雨强度（30、60和90 mm/h）和2个坡度（3°、5°）,研究降雨强度和坡度对典型黑土（Mollisol）农田顺坡垄体溅蚀量、溅蚀过程和溅蚀分选特征的影响。研究结果表明：当降雨强度由30 mm/h增加到90 mm/h时,总溅蚀量增加2.5～17.9倍。当坡度由3°增大到5°时,总溅蚀量增加30.52%～74.08%。当降雨强度为30和60 mm/h时,总溅蚀率随降雨历时呈迅速减小-缓慢减小-波动稳定的趋势。当降雨强度为90 mm/h时,总溅蚀率随降雨历时呈迅速增加-迅速减小-波动稳定的趋势。整体而言,总溅蚀量随降雨强度和坡度的增加呈幂函数关系。各试验处理下,溅蚀分选水稳性团聚体中均以<1 mm粒级的团聚体为主,平均占总量的79.01%,以0.5～1 mm粒级最多,2～5 mm粒级最少,分别占总量的32.94%和3.36%。30和60 mm/h降雨强度下,分别为<0.25和<2 mm的各粒级团聚体在降雨后期达到波动稳定,其中<0.25 mm的团聚体均呈迅速降低-缓慢降低-波动稳定的变化趋势。90 mm/h降雨强度下,1～5和<0.25 mm各粒级团聚体均呈线性平稳变化,其中<0.25 mm的团聚体呈线性减少趋势。研究可为东北黑土区水蚀防治提供科学依据。     

裸地雨滴溅蚀对坡面微地形的影响与变化特征

为了探讨溅蚀作用与坡面微地形之间的相互关系,该文通过模拟降雨试验方法,研究了黄土区坡耕地无植被条件下雨滴对坡面微地形的溅蚀作用与变化特征。微地形由不同的耕作管理措施形成,包括锄耕措施、掏挖措施和等高耕作措施,以平整坡面为对照措施。降雨强度分别为60,90和120mm/h。试验小区大小为0.5m2。用溅蚀板测定坡面向下和向上2个方向的溅蚀量。利用激光扫描仪测定微地形,并结合GIS技术建立大比例DEM(分辨率2cm)。结果表明,在耕作管理条件下,坡面微地形具有降低坡面溅蚀量的作用。微地形的变化特征主要表现为微坡度的变化,而微坡向对溅蚀作用的变化不敏感。因此,微坡度可以作为研究雨滴溅蚀作用与微地形变化的一个反映指标。     

江苏省沿海平原沙土区典型河沟边坡土壤侵蚀试验研究

为探明江苏省沿海平原沙土区河沟边坡土壤侵蚀过程并建立预测模型,在4个坡度和2个雨强条件下,对江苏省沿海平原沙土区典型河沟边坡土壤开展人工模拟溅蚀试验和微区模拟降雨试验,了解河沟边坡土壤溅蚀特征,明确河沟边坡产流产沙过程,并利用传递函数方法分别建立了溅蚀率、产流强度和产沙强度的估算模型.结果表明:(1)河沟边坡土壤溅蚀率...     

Revegetation techniques on clay soil slopes in northern Italy

Several standard techniques currently used in the reclamation and revegetation of former quarry land in Italy's northern Apennine region were compared. The trial site, a 40-degree slope with clay soil, high pH and a little organic matter, was arranged in a randomized block design. The techniques assayed were hydro-seeding+tillage, hydro-seeding on sod, straw mulch+tar, jute mats+tillage+hydro-seeding, jute mats+tillage and a control. Each plot was enriched with equal amounts of chopped straw (120 g m⁻²), worm compost (140 g m⁻²) and the fertilizer Biosol^® (140 g m⁻²); the binder Terravest^® (36 g m⁻²) was also used in the three hydro-seeded plots. Ground cover, species, runoff and erosion were compared in each treatment. The overall 3-year data indicate significant differences in the treatments tested. There is a clear distinction between the treatments that promoted good grass cover growth and checked erosion (straw and tar, jute on tilled soil, and hydro-seeding on jute and tilled soil) on the one hand and the hydro-seeded treatments (on sod and on tilled soil), which showed no differences from control, on the other. © 1997 John Wiley & Sons, Ltd.     

聚丙烯酰胺应用对黄土复合坡面降雨产流的影响

复合坡是自然界常见的主要坡型。通过室内人工降雨模拟试验,研究了复合坡面降雨产流规律以及聚丙烯酰胺（polyacrylamide,PAM）应用对其的影响。试验采用2种复合坡型（凹型坡和凸型坡）的12个坡度组合和4个PAM施用量,共48个试验处理。结果显示,PAM应用显著缩短了初始降雨产流时间,初始产流时间平均比对照处理提前63.7%～71.6%。PAM应用明显改变了坡面径流随降雨历时的变化规律。PAM应用后,除了大坡度（≥10°）、小量PAM应用（0.5 g/m2）的凸型坡外,降雨径流系数在整个降雨过程中基本维持稳定。PAM应用增大了降雨径流系数和径流量,且径流系数和径流量随着PAM施用量的增大而增大。凸型坡的径流量平均比凹型坡的大14.7%～31.8%。当PAM施用量为0.5、1.0和2.0 g/m2时,凹型坡和凸型坡的径流量分别比对照处理增加55.7%、100.2%、147.3%和16.6%、69.3%、108.9%。在黄土坡地上大剂量（≥1.0 g/m2）应用PAM可明显增大坡面径流量,实际应用中应制定合理的PAM施用量。     

降雨特性和坡度对辽西低山丘陵区坡耕地褐土溅蚀的影响

为揭示辽西低山丘陵区坡耕地典型土壤溅蚀特征,选取褐土为研究对象,采用人工模拟降雨试验研究降雨特性和坡度对溅蚀的影响。结果表明:随着降雨强度的增大,5°和10°溅蚀量分别由6.86g/cm和8.13g/cm增加到14.21g/cm和16.00g/cm,增加幅度为48.47%~209.81%;不同溅蚀距离内的溅蚀量表现为0~5cm>5~10cm>10~15cm>15~20cm>20~25cm,溅蚀距离0~5cm范围内的溅蚀量(75mm/h)为7.29g/cm,占0~25cm范围内总溅蚀量(16.00g/cm)的45.56%,溅蚀距离20~25cm范围内的溅蚀量仅占9.88%。溅蚀量与降雨强度和溅蚀距离均具有较好的指数关系,其回归方程的决定系数R2在0.8以上。随着降雨时间的延续,溅蚀量逐渐增加,但溅蚀量增长率呈减小的趋势;降雨历时由5min增加到10min时溅蚀量增长率最大。溅蚀量和降雨历时之间具有较好的指数关系,其回归方程的决定系数R2在0.9以上。随着降雨强度发生变化时,溅蚀团聚体空间分布规律也随之发生改变。各径级团聚体的溅蚀距离均随降雨强度的增大而增大,2~5mm团聚体由30mm/h的0~5cm扩大到75mm/h的0~15cm。溅蚀团聚体以粒径<1mm为主,小粒径团聚体溅蚀距离和溅蚀量均大于大粒径团聚体,>5mm团聚体并没有迁移。5°总溅蚀量、上坡溅蚀量、下坡溅蚀量、净溅蚀量(75mm/h)依次为14.21,3.54,10.67,7.13g/cm,10°依次为16.00,3.85,12.15,8.30g/cm,与5°相比显著增加12.60%,8.76%,13.87%,16.41%,下坡溅蚀量大于上坡溅蚀量。     

Response by soil nematode populations and the soil microbial biomass to a rain episode in the hot,dry Negev Desert

Since the amount, intensity, and frequency of rainfall in desert regions vary strongly over space and time, the response by soil biota to this variability is of great importance. We conducted a study in the Negev desert in order to examine the immediate response by the soil nematode populations and the microbial biomass to varying amounts of water applied in a single pulse. Soil samples from the 0–10-cm depth were collected from areas undergoing four different wetting treatments, comprising 5, 10, 15, and 20 mm of water, and from a non-irrigated control soil. There was a correlation between diurnal variations in nematode populations and the diurnal fluctuations in soil moisture. The greatest abundance of nematodes was found in the soil treated with 20 mm water (970 individuals 100 g^-1 dry soil) which was 2, 4, 5, and 14 times larger than that found in the soil treated with 15, 10, 5, and 0 mm of water, respectively. Bacterialfeeding and fungal-feeding nematodes accounted for approximately 95% of the total nematode population found in all treatments. The microbial biomass examined in the current study exhibited an immediate response to the wetting which was greater in soil treated with, 10, 15, and 20 mm of water compared with 0 and 5 mm. However, after 4 days (96 hours) the microbial biomass stabilized again at the basic level of the 0-mm control. However, our results indicated that the major trigger for changes in the nematode populations, and in the microbial biomass, was diurnal fluctuations in soil moisture, since peaks in nematode populations and in the microbial biomass were observed at various times of the day.     

聚丙烯酰胺对凹凸型坡土壤侵蚀影响的室内试验

通过室内人工模拟降雨试验,研究了聚丙烯酰胺(polyacrylamide,PAM)施用量(0、0.5、1.0和2.0 g/m2)对凸型坡(上、下坡坡度分别为5°、10°、15°和20°、25°)和凹型坡(上、下坡坡度分别为20°、25°和5°、10°、15°)土壤侵蚀规律的影响。结果显示,无PAM应用时,凹型坡或小坡度凸型坡(上坡坡度为5°)径流含沙量随降雨历时逐渐减小,而大坡度凸型坡(上坡坡度≥10°)径流含沙量在降雨过程中会急剧增大。凸型坡平均土壤流失量是凹型坡的8.4倍。PAM应用显著增大了凹型坡和小坡度凸型坡径流含沙量和土壤流失量(P0.05),但减小了大坡度凸型坡土壤流失量。PAM应用后,土壤流失量与坡度大小无明显关系,此时凸型坡平均土壤流失量为凹型坡的1.2倍。在生产实践中PAM可用于控制较陡(≥10°)凸型坡的土壤流失。     

Thermal shock and rain effects on soil surface characteristics: A laboratory approach

In addition to its direct impact on soil physical and chemical soil properties, fire produces a sudden change in plant cover. The post-fire impact of falling raindrops on unprotected soil surfaces is a major cause of detachment of aggregates, physical degradation and erosion of soils. The aim of this work was to analyse the effects of burning intensity and rain under factor-controlled conditions using unaltered soil samples. Assessed variables were soil organic carbon, aggregate stability and water repellency (0–1 cm mineral soil), as well as soil surface compaction and hydraulic conductivity. Unaltered topsoil cores were obtained in a mature Mediterranean gorse shrubland. We applied two successive treatments: burning (unburned, low and high burning levels) and rain (77 mm/h). The soil properties studied were scarcely affected by burning. However, soils showed high vulnerability to raindrop impact: a) aggregate stability and organic carbon were not significantly affected by burning; b) low intensity burning increased the frequency of samples with moderate water repellency, whereas unburned together with high burning showed more cases of low and extreme water repellency; c) the rain treatment produced a significant decrease in hydraulic conductivity although this response was independent of burning level; d) the highest reduction in hydraulic conductivity was observed in the samples with highest values prior to the rain treatment, and this was related to the highest organic carbon contents, and e) the reduction in hydraulic conductivity could be explained by the development of a thin and friable surface crust, although the cone penetrometer was not sensitive enough to detect this observed phenomenon.     

低丘陵山坡地逆温趋势分析

本研究通过探讨晴夜与非晴夜低丘陵山坡地逆温趋势规律结果表明:出现寒冻害的晴夜的低丘陵山坡地随相对坡位升高,与坡底温差增大,相对坡位与温差存在显著回归关系,逆温最高出现在山坡中上部,最低气温值出现在坡底;非晴夜不同相对坡位温差不大,最低气温均高于0℃,果树无冻害现象发生。晴夜最大逆温为3.3℃,不同坡向对温差变化幅度影响不大。     

陕北黄土丘陵沟壑区高速公路边坡不同生物防护模式的土壤特性—以铜（川）-黄（陵）-延（安）高速公路为例

以陕西省铜川-黄陵-延安高速公路（简称铜延高速公路）为例,选取不同防护模式（穴状整地植草模式、挂网喷播植草模式、骨架植草模式）下有代表性的18个边坡为研究对象,通过边坡土壤特性数据的处理分析,发现：1）铜延高速公路边坡干旱缺水,肥力匮乏,有机质和全氮处于极缺乏和缺乏等级,速效磷处于中等等级,平均含量为16．28mg／kg;2）土壤水分、土壤养分以及植被盖度均表现为阴坡〉阳坡,而土壤密度则是阳坡〉阴坡;土壤水分含量呈现下坡位〉上坡位〉中坡位规律,土壤养分含量呈现从上坡位到下坡位逐渐升高,有自上而下累积的趋势,植被盖度呈现明显的分层现象,表现为下坡位〉上坡位〉中坡位;3）3种护坡模式中,骨架植草模式涵养水分能力最强,其次是穴状整地植草模式,最后是挂网喷播植草模式;4）水分是黄土高原地区高速公路边坡防护成功与否的关键因子,另外施加有机肥和氮肥,保护和收集表层土,增施磷肥以及合理确定边坡坡度和斜面长对边坡的保水保肥性和稳定性意义重大。