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1.
植物根系提高土壤抗侵蚀性机理研究   总被引:4,自引:4,他引:65  
刘定辉  李勇 《水土保持学报》2003,17(3):34-37,117
介绍了近10年来植物根系提高土壤抗侵蚀性机理研究进展。植物根系稳定表土层结构、提高土壤入渗性能和抗剪强度、增强土壤抗冲性的有效性机理是植被抵抗径流侵蚀动态过程及土壤侵蚀预报研究亟待加强的关键科学问题。  相似文献
2.
为明确红壤结构特征与抗剪强度对坡面土壤分离能力的影响,选取8种典型红壤为研究对象,通过团聚体稳定性分析,饱和抗剪强度测定,和室内模拟冲刷试验,就各参数间定量关系进行了初步探讨。研究结果表明:团聚体稳定性特征参数As集合了红壤团聚体破碎的主要机制,与不同水流剪切力中红壤分离速率有较好的相关性;红壤饱和抗剪强度(σs)与集中水流内临界水流剪切力(τc)呈较好的线性关系。基于WEPP细沟侵蚀模型,将团聚体稳定性特征参数As代替可蚀性因子Kc,饱和抗剪强度(σs)代替临界水流剪切力(τc),得出新的预测方程。结果显示预测方程能准确的预测坡面集中水流内红壤分离速率(R2=0.887 1)。该结果为深入研究红壤侵蚀机理提供了新思路,对完善侵蚀物理过程模型具有重要的意义。  相似文献
3.
肖海  刘刚  刘普灵 《农业工程学报》2016,32(17):106-111
集中流引起的细沟侵蚀是黄土高原坡耕地主要侵蚀方式之一,对坡面集中水流动力学特性研究有利于掌握坡面集中流剥蚀产沙的根本原因,但目前哪种集中流水动力学参数最能准确揭示侵蚀动力过程机理尚不明确。该文采用室内集中流放水冲刷试验,以黄土高原典型黄绵土为研究对象,研究坡面平均和瞬时剥蚀率与相应水流剪切力、水流功率、单位水流功率以及过水断面单位能量之间的关系。结果表明,除了瞬时过水断面单位能量拟合效果较差外,其他平均和瞬时水力学参数均能够较好地与坡面剥蚀率建立不同的拟合关系。所有参数中平均水流功率是描述本试验条件下的最优水力学参数。由于细沟发育过程中大量坍塌的出现,导致整个径流剪切力和水流功率与剥蚀率之间的关系曲线整体上升,出现了临界剪切力和临界水流功率为负值的情况。通过与仅考虑水流对坡面直接作用参数所得结果对比,表明坍塌等作用在细沟发育过程中具有重要影响,对剥蚀率的贡献可达90.93%。研究可为控制和预防集中流侵蚀发生提供科学依据。  相似文献
4.
Surface roughness is thought to affect concentrated flow erosion – a major mechanism of soil loss on disturbed rangelands. However, quantifying surface roughness in the field at appropriately fine spatial scales is laborious and the scale at which to conduct meaningful roughness measurements is difficult to discern. Rapid, objective, and repeatable field methods are therefore needed to accurately measure surface roughness across a range of spatial scales to advance our understanding and modeling of concentrated flow erosion processes. Surface roughness can be derived from surface topography mapped at the sub-cm level using a field-portable terrestrial laser scanner (TLS). To test the suitability of terrestrial laser scanning for studying surface roughness effects on erosion processes in rangelands, we used concentrated flow simulation techniques at 8.5 m2 plots that were randomly placed at rangeland sites in southeastern Oregon and southwestern Idaho, USA. Local surface roughness (locRMSH) was calculated as the standard deviation of TLS mapped surface heights within moving windows varying in size from 30 × 30 to 90 × 90 mm. The mean locRMSH of the eroded area and entire plot were negatively correlated (r2 > 0.71, RMSE < 95.97 g min− 1, and r2 > 0.74, RMSE < 90.07 g min− 1, respectively) with concentrated flow erosion. The strength of the locRMSH–erosion relationship and regression model parameters were affected by the moving window size, emphasizing the scale dependence of the locRMSH–erosion relationship. Adjusting locRMSH for slope effects decreased the strength of the locRMSH–erosion relationship from r2 < 0.83 to < 0.26. Our results indicate that TLS is a useful tool to enhance our current understanding of the effect of surface roughness on overland flow erosion processes and advance hydrologic and erosion model parameter development. Further research is needed to evaluate the locRMSH – concentrated flow erosion relationship over a wider range of soil properties, surface conditions, and spatial extents.  相似文献
5.
通过室内人工放水冲刷试验,探究不同流量(2 L/min,4 L/min,8 L/min,16 L/min)和砾石含量(0%,20%,40%,60%)条件下,土石混合崩积物坡面产沙特征.结果表明:各条件下产沙过程均呈先增大后减小再趋于稳定的趋势.产沙量随着流量的增大而增大,而含沙量随流量的增大总体呈减小的趋势;在2 L/min和4 L/min条件下,产沙量及含沙量随着砾石含量的增大呈先减小后增大的趋势,存在临界砾石含量(20%~40%);在8 L/min和16 L/min条件下,产沙量及含沙量随着砾石含量的增大而增大.产沙率与含沙量的关系表明,含石量对产沙的影响存在临界含石量(20%~40%).砾石含量和流量可以用来很好地预测土石混合崩积物的产沙率,但对含沙量的预测效果较差.流量对产沙率及含沙量的影响均大于砾石含量.  相似文献
6.
基于泾河流域1965 2014年59月的逐日降雨量、逐日径流量和逐日含沙量数据,选取日含沙量≥100 kg/m3作为高含沙水流,分析了泾河高含沙水流的空间特征及其变化,并参考降雨量探讨变化成因.结果表明,研究期内泾河流域的高含沙水流变化可以分为3个阶段:1965-1978年为多发期,1979-1990年为略微减少期,2006-2014年为显著减少期.将泾河流域分为南北两个分支,高含沙水流具有明显的尺度效应,北支的产沙模数随流域面积增加而减少,产流模数随流域面积增加而增加,南支的产沙模数随流域面积增加而增加,产流模数也随流域面积增加而增加.南北两个分支的产流模数和产沙模数在3个阶段经历了相似的变化,先是1979 1990年略微减少,之后在2006-2014年显著减少,使最初的复杂尺度效应转变为后期简单的线性尺度效应.分析结果说明泾河流域内部各区域在水土保持措施长期实施下高含沙水流均得到有效控制.  相似文献
7.
Soil erodibilty during concentrated flow (Kc) and critical flow shear stress (τcr), both reflecting the soil's resistance to erosion by concentrated runoff, are important input parameters in many physically-based soil erosion models. Field data on the spatial and temporal variability of these parameters is limited but crucial for accurate prediction of soil loss by rill or gully erosion. In this study, the temporal variations in Kc and τcr for a winter wheat field on a silt loam soil under three different tillage practices (conventional ploughing, CP; shallow non-inversion tillage, ST; deep non-inversion tillage, DT) in the Belgian Loess Belt were monitored during one growing season. Undisturbed topsoil samples (0.003 m3) were taken every three weeks and subjected to five different flow shear stresses (τ = 4–45 Pa) in a laboratory flume to simulate soil detachment by concentrated flow. To explain the observed variation, relevant soil and environmental parameters were measured at the time of sampling. Results indicated that after two years of conservation tillage, Kc(CP) > Kc(DT) > Kc(ST). Kc values can be up to 10 times smaller for ST compared to CP but differences strongly vary over time, with an increasing difference with decreasing soil moisture content. The beneficial effects of no-tillage are not reflected in τcr. Kc values vary from 0.006 to 0.05 sm−1 for CP and from 0.0008 to 0.01 sm−1 for ST over time. Temporal variations in Kc can be mainly explained by variations in soil moisture content but consolidation effects, root growth, residue decomposition and the presence of microbiotic soil crusts as well play a role. τcr values increase with increasing soil shear strength but Kc seems more appropriate to represent the temporal variability in soil erosion resistance during concentrated flow. The large intra-seasonal variations in Kc, which are shown to be at least equally important as differences between different soil types reported in literature, demonstrate the importance of incorporating temporal variability in soil erosion resistance when modelling soil erosion by concentrated flow.  相似文献
8.
Soil erosion on agricultural land and its detrimental environmental and economical effects has aroused increased interest among both the research and policy-making communities. The call for erosion control measures adapted to local farming practices is high, especially in Europe where farmers are reluctant to adopt soil conservation techniques. This study investigates a new technique for controlling concentrated flow erosion rates in the loess belt of central Belgium: i.e. double drilling of cereals in zones of concentrated flow. Cross-sectional areas of erosion channels as well as crop yield parameters in single- and double-drilled zones were compared. The technique is based on the combined effect of the increased density of plant shoots and roots for reducing soil loss. Results indicate that double drilling can reduce soil loss through concentrated flow by 25% on average and by up to 40% under optimal conditions. No net change in wheat grain yield was observed, and farmers who participated in the experiments were satisfied with the results and the easy application of the technique. Globally, benefits were larger than costs. However, the effectiveness of the technique in reducing soil loss by concentrated flow erosion seems to be topographically restricted. For positions in the landscape with a contributing drainage area larger than ca. 0.75 ha, the effectiveness of double drilling can be doubted. Double drilling should therefore be regarded as one possibility amongst others to reduce concentrated flow erosion rates in farmers’ fields.  相似文献
9.
Rare earth element oxides (REOs) have excellent potential for use as tracers in erosion studies. Using laboratory and field experiments we aimed to develop and test a simple application method for spreading REOs and to use REOs to determine the source of sediment to concentrated overland flow paths.  相似文献
10.
研究了5种模拟糙度和6种不同冲刷距离组合下3种粒径的红壤团聚体在集中水流内的剥蚀破坏规律,分析了糙度、运移距离以及相关水力学参数对团聚体剥蚀破坏的影响。结果表明,在相同运移距离条件下,随粒径和糙度的增加团聚体剥蚀破坏程度呈增加趋势,与粒径相比,糙度对剥蚀破坏程度的影响更大。相同模拟糙度下,随着运移距离的增加,剥蚀率均呈抛物线形先增大后减小的趋势;各运移距离下,7~5 mm粒径团聚体的剥蚀率随糙度的增加而增加;5~3 mm和3~1 mm粒径团聚体在各运移距离内随糙度的增加变化规律不一致。在不同糙度情况下,以运移距离等于36 m为例,团聚体与原始团聚体质量比(Wr /Wi)随径流水深、阻力系数、水流剪切力的增加均呈幂函数减小之后趋于平缓的趋势。该结果为研究红壤团聚体破碎理论机制提供了参考,对于完善土壤侵蚀过程模型,具有重要的理论意义。  相似文献
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