上方来水对坡面降雨入渗及土壤水分再分布的影响

在防止土壤侵蚀和雨后抑制蒸发的条件下,利用室内模拟降雨试验,研究了上方来水对坡面降雨入渗、湿润锋运移以及土壤水分再分布的影响。结果表明:对于初始含水量很低的土壤,与上方无来水相比,上方来水时降雨入渗过程中入渗率有一个上升的阶段,但平均入渗率反而降低;在降雨入渗初期,由于上方来水的沿程入渗,上方来水对坡面湿润锋运移的影响较大,但随后几乎没有影响,湿润锋的运移主要与基质势梯度有关;土壤水分沿坡面呈"波浪形"分布是坡面径流的波动性、上方来水(径流)的沿程入渗以及侧向沿坡向下流等综合作用的结果。     

微生物诱导矿化加固粉土坡面的径流与侵蚀特性

微生物诱导碳酸盐沉淀（MICP）是一种微生物矿化过程,能够胶结松散土体。将其应用于加固土体坡面提高抗降雨侵蚀能力具有潜在的发展前景。通过模拟降雨冲刷试验,对微生物诱导矿化加固前后粉土坡面的径流水动力与侵蚀特性开展研究,分析和讨论了水动力参数之间的相关性以及对土壤剥蚀率的影响规律。结果显示,加固后与加固前相比,粉土坡面径流的弗劳德数平均下降50%;在降雨前期的阻力系数平均下降66%,径流稳定后二者阻力系数接近;径流剪切力平均提高52%。径流系数与坡面入渗速率呈线性负相关（R²=0.857）,与加固层的贯入强度呈指数负相关（R²=0.824）;入渗速率与加固层的贯入强度呈二次负相关R²=0.930）;径流剪切力与坡度呈指数正相关（R²=0.964）。加固粉土坡面的剥蚀率与加固层的贯入强度呈指数负相关（R²=0.822）,与径流剪切力线性正相关（R2=0.912）,临界径流剪切力为0.5 Pa。对于坡度10~25°的粉土坡面,微生物加固能将其剥蚀率从58.2~118.4 g/m2s降至2.4~21.2 g/m2s,剥蚀率最大降幅可达95.0%。粉土坡面经微生物诱导矿化加固后,水动力参数值发生显著变化,径流特性与水动力参数、加固层特性及坡度相关,坡面的抗冲刷侵蚀性能得到有效提升。     

植被措施与路面汇水对三峡库区土质道路边坡侵蚀影响

研究土质道路边坡在自然恢复、草本、草灌结合及植生带等4种不同植被恢复模式下的降雨侵蚀特征,同时将模拟降雨试验和冲刷试验相结合,研究路面汇水的介入对路堤边坡侵蚀的影响。研究结果表明,在模拟降雨试验下,草灌结合控制路堑边坡侵蚀效果最佳,产流量和产沙量显著低于其他植被模式;草本和草灌结合在路堤边坡降雨和冲刷下,都有显著的截流拦沙能力,且两种措施防护效果相当;路面来水的介入对路堤边坡侵蚀有显著促进作用,加速产流,增加产流量和产沙量。山区道路侵蚀的治理,不但要因地制宜地选择适宜的防护措施,更应该对路面产流和路面汇流进行科学合理的规划,减少其对路面及路堤的冲刷侵蚀。     

黄土丘陵区堆积体边坡对上方来水的侵蚀响应

为探明上方来水类型对工程堆积体高陡边坡下部冲刷侵蚀的定量影响,以神府高速公路沿线典型工程堆积体陡坡坡面(36°)为例,设计4种上方来水类型,通过野外放水冲刷试验分析了不同上方来水类型下堆积体坡面的径流侵蚀输沙过程.结果表明:①上方来水类型对堆积体坡面下部的产流影响较小,却干扰了坡面侵蚀产沙过程,造成土壤流失量增加;②径流深、单宽径流侵蚀力和水流功率均可以较好地预测堆积体边坡下部输沙模数的变化;③单宽径流侵蚀功率可以作为表征坡面尺度次径流事件中径流侵蚀力变化的指标.研究结果可为工程堆积体土壤侵蚀强度评价、侵蚀模型建立及新增水土流失防治提供参考.     

植被作用下土壤抗剪强度和径流侵蚀力的耦合效应

利用野外径流小区动态监测和人工模拟降雨试验,阐明了草被和灌木的减流减沙效应,从力学层面揭示了坡面侵蚀产沙的过程机理。结果表明,与裸地相比,野外坡面草地和灌木地径流量分别减少28.1%~56.5%和85.7%~100%、产沙量分别减少84.9%~90.7%和98.5%~100%;在人工模拟降雨强度下,草地和灌木地径流量分别减少51.9%~90.9%和61.7%~80.6%、产沙量分别减少93.6%~99.2%和95.5%~99.2%;植被具有明显的增强土壤抗剪强度的作用,不同植被坡面抗剪强度与剪切面上的法向压力成正比,且符合库仑定律;不同下垫面条件下土壤黏聚力与坡面径流量和侵蚀产沙量呈显著的负相关关系,随着黏聚力的增大,径流量和侵蚀产沙量呈下降趋势;草地和灌木地坡面侵蚀临界径流切应力分别为裸地的2.64~3.16倍和2.44~3.18倍,建立了不同被覆坡面临界径流切应力与土壤抗剪强度和黏聚力的关系。研究结果对定量评价植被减蚀作用和深化土壤侵蚀力学过程有一定的参考意义。     

降雨侵蚀力对露天矿排土场边坡水土流失的影响研究

降雨侵蚀力反应降雨引起的土壤侵蚀潜在能力,是水土保持研究中的主要指标之一。以露天煤矿排土场不同覆盖类型边坡为研究对象,分析了日降雨侵蚀力与边坡侵蚀的关系。结果表明,从控制坡面径流深来看,降雨侵蚀力的作用受到了乔灌草和灌草配置的显著影响,其产生的坡面径流仅为对照区的42.9%和52.6%。从控制坡面侵蚀量来看,三种植物配置措施都具有显著减少功能,土壤侵蚀量仅为对照区的2.3%~6.7%。降雨侵蚀力与边坡水土流失量存在线性正相关,其中坡面径流深对降雨侵蚀力的响应快于土壤侵蚀量。     

黄土丘陵区土壤侵蚀链垂直带水沙流空间分布

采用多坡段组合模型、人工模拟降雨实验研究了土壤侵蚀链垂直带水沙流空间分布变化特征。结果表明:愈向下坡方向的坡段产流量愈大,单位面积、单位时间的产流量按坡段排列为:谷坡>梁峁坡下部>梁峁坡中部>梁峁坡上部。雨强为29.7mm/h时,坡面上没有沟蚀发育;雨强为60.5mm/h时,细沟主要分布在梁峁坡下部和谷坡处;雨强为90 2mm/h时,各种侵蚀形态在坡面均有较好发育,细沟的出现部位一直伸展到梁峁坡中部和上部之间。由于上坡来水来沙的作用,梁峁坡的产沙量增大了20.2%～63.5%,谷坡的产沙量增大了42.9%～74.5%。     

不同植被类型的坡面径流侵蚀产沙试验研究

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。     

Study on the runoff and sediment-producing effects of precipitation in headwater areas of the Yangtze River and Yellow River,China

Natural runoff observation fields with different vegetation coverage were established in the Zuomaoxikongqu River basin in the headwater area of the Yangtze River, and in the Natong River basin and the Kuarewaerma River basin in the headwater area of the Yellow River, China. The experiments were conducted using natural precipitation and artificially simulated precipitation between July and August to study the runoff and sediment-producing effects of precipitation under the conditions of the same slope and different alpine meadow land with coverage in the headwater areas. The results show that, in the three small river basins in the headwater areas of the Yangtze and the Yellow Rivers, the surface runoff yield on the 30° slope surface of the alpine meadow land with a vegetation cover of 30% is markedly larger than that of the fields with a vegetation cover of 95, 92, and 68%. Furthermore, the sediment yield is also obviously larger than the latter three; on an average, the sediment yield caused by a single precipitation event is 2–4 times as large as the latter three. Several typical precipitation forms affecting the runoff yield on the slope surface also influence the process. No matter how the surface conditions are; the rainfall is still the main precipitation form causing soil erosion. In some forms of precipitation, such as the greatest snow melting as water runoff, the sediment yield is minimal. Under the condition of the same precipitation amount, snowfall can obviously increase the runoff yield, roughly 2.1–3.5 times as compared to the combined runoff yield of the Sleet or that of rainfall alone; but meanwhile, the sediment yield and soil erosion rate decrease, roughly decreasing by 45.4–80.3%. High vegetation cover can effectively decrease the runoff-induced erosion. This experimental result is consistent in the three river basins in the headwater areas of the Yangtze and Yellow Rivers.     

The efficiency of artificial materials used for erosion control on steep slopes

This study investigates the performance of artificial materials used for erosion control on steep slopes under high rainfall intensity. Soil samples were laid on a 300 × 100 cm platform inclined at either 35° or 45°, after which the soil was covered with various materials and subjected to a rainfall intensity of 130 mm/h for an hour. A wooden-block net covered with a jute net resulted in the greatest erosion resistance, providing 83% resistance at 35° and 76% at 45°. On the 35° slope, the artificial materials showed relatively good erosion resistance. As the slope was raised to 45°, some of the materials did not attach effectively to the soil surface. Thus, the runoff velocity increased and erosion became severe. For optimum erosion resistance, the material used to protect soil must attach to the soil surface well and have structural properties, such as a high coverage ratio to reduce the impact of rainfall on the soil and uniformly distributed transverse structures to reduce runoff energy and trap soil.     

植草沟径流调控效果对关键设计参数的响应规律模拟

为分析道路低影响设施植草沟主要设计参数对地表径流调控作用的影响规律,应用一套耦合了水文和水动力过程的数值模型,研究各设计参数对植草沟径流控制作用的调控效果,经验证模型模拟精度可满足研究要求。模拟结果表明:植草沟具有削减洪峰洪量、推迟峰现时间的作用。且溢流井位于入水口上游侧,横、纵坡坡度越缓时,植草沟径流控制效果越显著。溢流井位置改变时径流控制效果差值达2%~10%,峰值削减差异为13%~28%;横坡坡度从1/3~1/7变化时,径流控制率提高4%~13%,峰值削减效果提升6%~23%;纵坡坡度从0.5%~0.3%变化时,径流控制率提高7%~16%,峰值削减效果提升12%~29%。数值模拟得出各设计参数的影响规律,可用于指导植草沟的规划设计,为其推广应用提供参考。     

黄土高原草本植被水土保持作用研究进展

草本植被具有积极的保持水土的作用，在黄土高原生态环境建设中具有不可替代的作用。在系统分析黄土高原草本植被保土减蚀作用研究的过去与现状的基础上，归纳并总结了草被覆盖度与水土流失量、草被植物与地表径流系数、草被植物地下根系与土壤抗冲性及抗蚀性等方面的最新研究进展，并针对各方面存在的问题以及今后有待深入研究的问题进行了探讨。     

Advances in Researches of the Effects of Grassland Vegetation on Soil Erosion in Loess Plateau

Soil erosion is a serious global environmental problem which limits the survival and development of human beings. In our country, due to the special physical geography and socio-economic conditions, soil erosion intensity is great, which is particularly prominent in Loess Plateau region. Therefore, preventing and controlling soil erosion, as well as reducing soil erosion in Loess Plateau have become the key to solving environmental problems in the region. Soil erosion on Loess Plateau is serious, and grassland vegetation has good effects on soil and water conservation, which can improve ecological environment well. After the implementation of the project about returning farmland to grassland on Loess Plateau, the ecological benefits mainly focused on soil and water conservation benefits, soil improvement benefits, water conservation benefits and species diversity benefits, etc. Grassland vegetation has an irreplaceable role in the construction of the ecological environment on Loess Plateau. Therefore, the role of grassland in preventing soil erosion has received more and more attention. Scholars have done lots of research involved in the relationship between grassland coverage and soil erosion, impacts of grassland on hydrodynamic parameters, effects of grassland on soil properties, reduction effects of grassland on runoff and sediment, and soil erosion process on grassland slope. However, there is little research on erosion effect induced by grassland cover. This paper mainly pointed out the following questions: First, grassland cover is influenced by many factors, but the relationship with soil erosion from the dynamic mechanism is rarely discussed; Second, there is no well-developed theory of overland flow erosion at present, which limits the study of hydrodynamic parameters on grassland slope; Third, establishment of mathematical model between grassland cover and soil resistance can accelerate the quantitative analysis of grassland influence on erosion; Fourth, comprehensive analysis of influencing factors on water reduction and sediment reduction effect on grassland are insufficient; Fifth, there are not many mechanisms to analyze the erosion process of grassland slope by using the hydrodynamic characteristics of slope; sixth, research results on grassland-induced erosion are mainly focused on leading to soil dry layer and we should continue to strengthen in the future. This paper summarized the previous results, and supplemented some studies about erosion caused by grassland, then pointed out the existing problems in current research and the areas that need to be strengthened in the future, aiming at reducing soil erosion on the Loess Plateau.     

黄土高原草本植被水土保持作用研究进展

草本植被具有积极的保持水土的作用,在黄土高原生态环境建设中具有不可替代的作用。在系统分析黄土高原草本植被保土减蚀作用研究的过去与现状的基础上,归纳并总结了草被覆盖度与水土流失量、草被植物与地表径流系数、草被植物地下根系与土壤抗冲性及抗蚀性等方面的最新研究进展,并针对各方面存在的问题以及今后有待深入研究的问题进行了探讨。     

开发西部切入点的研究──以黄土高原生态环境建设切入点为例

本本文以黄土高原为例, 讨论了生态环境建设作为开发西部切入点的科学和实际意 义。从黄土高原毁林毁草耕垦和人为加速侵蚀的发展, 剖析了退耕还林还草作为生态环境建 设切入点的科学依据。在此基础上, 又进一步剖析了退耕还林还草的切入点及其实施对策。     

Impacts of vehicles on natural terrain at seven sites in the San Francisco Bay area

The impacts of off-road vehicles on vegetation and soil were investigated at seven representative sites in the San Francisco Bay area. Plant cover of grass and chaparral (with shrubs to 4 m tall) have been stripped by the two- and four-wheel vehicles in use. Impacts on loamy soils include increased surface strength (as much as 275 bars), increased bulk density (averaging 18%) to depths of 90 cm or more, reduction of soil moisture by an average 43% to 30 cm depths, greatly reduced infiltration, extension of the diurnal temperature range by as much as 12°C, and reduction of organic carbon by an average 33% in exposed soils. Very sandy soils respond similarly to vehicular use except that moisture is increased and surface strength of beach sand is decreased. These physical and chemical impacts reduce the land's capability of restoring its vegetative cover, which in turn adversely affects animal populations. Both the loss of plant cover and the physical changes caused by vehicles promote erosion. Measured soil and substrate losses from vehicular use zones range from 7 to 1180 kg/m². The estimated erosion rate of the Chabot Park site exceeds the rate of erosion considered a serious problem by a factor 30, it exceeds United States Soil Conservation Service tolerance values by a factor of 46, and it exceeds average San Francisco Bay area erosion rates by a factor of 17. The resulting soil losses are effectively permanent. Neither the increased sediment yield nor the increased runoff is accomodated on the sites of use, and both are causing adverse effects to neighboring properties.     

降雨条件下微生物技术治理崩岗侵蚀

崩岗是中国花岗岩地区危害最大的一种土壤侵蚀方式,坡面防护是崩岗侵蚀治理的重要措施。为研究微生物诱导碳酸钙沉淀（MICP）技术在花岗岩崩岗侵蚀区冲刷防护中应用的可行性,以福建省崩岗最为发育的安溪县官桥镇花岗岩土质覆盖层为研究对象,进行降雨条件下微生物治理崩岗的模型试验研究。采用喷洒加固法对崩岗坡面进行处理,然后利用降雨模拟系统冲刷坡面,最后分析了MICP加固技术对泥沙产量及坡面侵蚀深度的影响。结果表明：与未加固边坡相比,MICP固化边坡泥沙产量由未加固的7648.43 g下降至266.61 g,较加固之前降低了96.51%;最大侵蚀深度由未加固的60 mm下降至除个别侵蚀坑外边坡表面基本未发生侵蚀。     

不同加固技术在散粒体斜坡表层的应用对比研究

散粒体斜坡多发育于我国西部山区,由块度不一、黏粒含量较少的碎砾石土组成,由于胶结性差,遇雨水冲刷、风吹或人畜踩踏易失稳。传统坡面防护技术包括拦挡锚固和土工材料与植被构筑,新型护坡技术是结合了岩土材料加固和生态环境两方面所提出的新方法。本文中该新技术是指将浓度1.3%的改性钠羧甲基纤维素与边坡表层土拌合,后掺入植物纤维,喷洒到坡表形成加固层;加固层表面喷洒草籽,以达到边坡防护的目的。文章选择传统的护坡方法（格构和三维网）和新型土壤改良方法结合植草绿化技术对室外某散粒体斜坡进行加固处理,以天然斜坡为参照,统计降雨冲刷和径流冲刷后边坡表面侵蚀破坏、入渗和植被破坏特征,对比不同护坡方式的应用效果。试验结果表明:每个斜坡辅之相同的植草条件下,对比降雨和放水冲刷试验后各边坡的侵蚀破坏特征可以发现,材料改良植草边坡侵蚀弱,产沙量小,作用层能减缓雨水下渗,提高植被存活率和降低植被倒伏率,其效果优于三维网植草护坡和格构植草护坡。     

三维土工网垫植草护坡防坡面径流冲刷的机制分析

基于水力学和河流动力学的基本原理,利用坡面糙率和拦污栅模型分别模拟三维土工网垫和坡面植被作用,建立了三维土工网垫和坡面植被引起的坡面沿程水头损失和径流局部水头损失计算式,并建立三维土工网垫植草护坡时坡面径流速度计算表达式,将颗粒启动速度引入分析坡面土颗粒流失初始的启动流速,进而通过坡脚流速和坡面土颗粒启动流速的对比分析和通过分析坡角、植株密度、网垫和植被类型对坡脚流速的影响来研究三维土工网垫植草护坡的防径流冲刷特性。结果表明,坡脚流速随坡角增大而增大;网垫类型对坡脚流速影响不明显,但同无护坡时相比网垫能显著降低坡脚流速;坡脚流速随植株和叶部倾角增加而变小,且随植株密度增大而减少,并在考虑不同边坡土质的颗粒启动速度与坡脚流速相等时计算得到护坡所需的植株最小密度。     

The relative importance of soil crust and slope angle in runoff and soil loss: a case study in the hilly areas of the Loess Plateau, North China

Soil crust and slope angle are of important factors affecting runoff production and sediment yield. In the hilly areas of the Loess Plateau, North China, slope lands are distributed extensively and subjected to soil crusting; therefore, the research on the responses of runoff and soil loss to soil crust and slope angle is essential to soil and water conservation. In the study, five pairs of 1 m × 5 m plots with slope angles of 5°, 10°, 15°, 20° and 25° respectively, were established in Wangjiagou watershed, which was located at the Loess Plateau, China. Based on the two simulated rainfall events, uncrusted surface prior to the first simulated rainfall event, and crusted surface prior to the second rainfall event were distinguished. The runoff production and soil loss were measured at intervals of 5 min during the simulated events. It indicated that both soil crust and slope angle played an important role in runoff production and soil loss. With the reference slope angle of 5°, the relative importance of soil crust and slope angle in runoff production was calculated. It showed that soil crust effect on the total runoff volume decreased from 100 to ～40%, while slope angle effect increased from 0 to ～60% with increasing slope angle because soil crust less developed on the steeper slopes. Furthermore, soil crust effect was associated with rainfall duration. At the same slope angle, the relative importance of soil crust decreased with rainfall duration because new crust was formed on the uncrusted surface. The critical slope of erosion was also discussed. Soil loss increased with slope angle when the slope angle was less than 20°. Generally speaking, soil crust effect decreased with slope angle and/or rainfall duration.