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1.
泥沙搬运是小流域土壤侵蚀、搬运和沉积过程中一个很重要子过程,搬运能力的定量研究是刻画土壤侵蚀过程和建立物理过程侵蚀模型的理论基础。对于目前被广泛采用的坡面漫流输移方程和沟道挟沙水流方程的试验条件进行了比较分析,探讨了其在黄土高原地区侵蚀模拟过程中的应用可能性和局限性。同时,表述了在黄土高原地区选择搬运能力方程需要考虑修正条件的必要性。 相似文献
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针对坡面径流水深浅(1～5mm)和水动力学参数(流速、水深等)提取困难,给坡面侵蚀径流水流结构、能量耗散及泥沙输移等的深入研究带来困难的问题,基于水动力学原理和相似性理论,通过"非常规比尺模型"将径流水深进行放大,来研究坡面薄层含沙水流的水流相似过程。结果表明:(1)当薄层含沙水流水深放大2.5倍,含沙量在10～320kg/m~3时,薄层含沙水流原型和模型的水面线(阻力)、流速、侵蚀地形的误差分别为0～0.1%,0.1%～5.3%,0.9%～4.9%,误差均在允许范围之内,原型和模型满足几何、运动等相似比尺转换关系;(2)水深在0.5～1.25cm时,薄层含沙水流为紊流,原型和模型的流速垂向分布满足对数分布,可以用同一方程进行表达;(3)"非常规比尺模型"可以作为一种方法应用到薄层含沙水流的水动力学参数提取、水流结构、能量耗散、泥沙输移等的深入研究过程中。 相似文献
3.
In this study, a finite element method based soil erosion and sediment yield model has been developed for overland and stream flow. The one dimensional conservation of mass of sediment flow equation has been solved based on kinematic wave flow approximation and Galerkin's based numerical solution. Various thematic maps required for the model are prepared using Geographical Information System (GIS). Land use/Land cover is extracted from remotely sensed data. The proposed finite element based distributed model has been used for the estimation of soil erosion and sediment outflow by discretizing the watershed into small grids. The soil erosion and sediment outflow model has been developed and applied to Khadakohol watershed located in Nashik district of Maharastra state, India. Part of the available data has been used for the model calibration and the other part for model validation. The simulated results of the watershed have been compared with the observed data and found to be satisfactory. 相似文献
4.
由降雨事件引起的坡面产流和土壤侵蚀的元胞自动机模拟 总被引：2，自引：0，他引：2
A novel quantitative cellular automata (CA) model that simulates and predicts hillslope runoff and soil erosion caused by rainfall events was developed by integrating the local interaction rules and the hillslope surface hydraulic processes. In this CA model, the hillslope surface was subdivided into a series of discrete spatial cells with the same geometric features. At each time step, water and sediment were transported between two adjacent spatial cells. The flow direction was determined by a combination of water surface slope and stochastic assignment. The amounts of interchanged water and sediment were computed using the Chezy-Manning formula and the empirical sediment transport equation. The water and sediment discharged from the open boundary cells were considered as the runoff and the sediment yields over the entire hillslope surface. Two hillslope soil erosion experiments under simulated rainfall events were carried out. Cumulative runoff and sediment yields were measured, respectively. Then, the CA model was applied to simulate the water and soil erosion for these two experiments. Analysis of simulation results indicated that the size of the spatial cell, hydraulic parameters, and the setting of time step and iteration times had a large impact on the model accuracy. The comparison of the simulated and measured data suggested that the CA model was an applicable alternate for simulating the hillslope water flow and soil erosion. 相似文献
5.
Distributed erosion models are potentially good tools for locating soil sediment sources and guiding efficient Soil and Water Conservation (SWC) planning, but the uncertainty of model predictions may be high. In this study, the distribution of erosion within a catchment was predicted with a semi-empirical erosion model that combined a semi-distributed hydrological model with the Morgan, Morgan and Finney (MMF) empirical erosion model. The model was tested in a small catchment of the West Usambara Mountains (Kwalei catchment, Tanzania). Soil detachability rates measured in splash cups (0.48–1.16 g J− 1) were close to model simulations (0.30–0.35 g J− 1). Net erosion rates measured in Gerlach troughs (0.01–1.05 kg m− 2 per event) were used to calibrate the sediment transport capacity of overland flow. Uncertainties of model simulations due to parameterisation of overland flow sediment transport capacity were assessed with the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. The quality of the spatial predictions was assessed by comparing the simulated erosion pattern with the field-observed erosion pattern, measuring the agreement with the weighted Kappa coefficient of the contingency table. Behavioural parameter sets (weighted Kappa > 0.50) were those with short reinfiltration length (< 1.5 m) and ratio of overland flow power α to local topography power γ close to 0.5. In the dynamic Hortonian hydrologic regime and the dissected terrain of Kwalei catchment, topography controlled the distribution of erosion more than overland flow. Simulated erosion rates varied from − 4 to + 2 kg m− 2 per season. The model simulated correctly around 75% of erosion pattern. The uncertainty of model predictions due to sediment transport capacity was high; around 10% of the fields were attributed to either slight or severe erosion. The difficult characterisation of catchment-scale effective sediment transport capacity parameters poses a major limit to distributed erosion modelling predicting capabilities. 相似文献
6.
退耕驱动的近地表特性变化对土壤侵蚀的潜在影响 总被引：8，自引：0，他引：8
张光辉 《中国水土保持科学》2017,(4):143-154
黄土高原是我国、乃至全球土壤侵蚀最严重的区域之一,侵蚀强度及时空分布特征受近地表特性的显著影响.退耕还林(草)工程大面积的有效实施,势必会引起近地表特性(土壤理化性质、植被茎秆、枯落物、生物结皮、根系系统)的显著变化,进而对坡面径流的水动力学特性及侵蚀过程产生影响.本文从退耕驱动的近地表特性变化、近地表特性变化对坡面径流水动力学特性的影响、近地表特性变化对土壤侵蚀过程(土壤分离、泥沙输移、泥沙沉积)的影响及其机制、区域土壤侵蚀对退耕的响应4个方面较为系统地总结近几十年国内外的研究成果,并提出了目前亟待强化的研究领域.这对理解退耕坡面土壤侵蚀过程及其动力机制、建立植被覆盖坡面的土壤侵蚀过程模型、评价退耕坡面的水土保持效益,具有重要的理论意义. 相似文献
7.
M. J. Kirkby B. J. Irvine R. J. A. Jones G. Govers PESERA team 《European Journal of Soil Science》2008,59(6):1293-1306
The principles and theoretical background are presented for a new process‐based model (PESERA) that is designed to estimate long‐term average erosion rates at 1 km resolution and has, to date, been applied to most of Europe. The model is built around a partition of precipitation into components for overland flow (infiltration excess, saturation excess and snowmelt), evapo‐transpiration and changes in soil moisture storage. Transpiration is used to drive a generic plant growth model for biomass, constrained as necessary by land use decisions, primarily on a monthly time step. Leaf fall, with corrections for cropping, grazing, etc., also drives a simple model for soil organic matter. The runoff threshold for infiltration excess overland flow depends dynamically on vegetation cover, organic matter and soil properties, varying over the year. The distribution of daily rainfall totals has been fitted to a Gamma distribution for each month, and drives overland flow and sediment transport (proportional to the sum of overland flow squared) by summing over this distribution. Total erosion is driven by erodibility, derived from soil properties, squared overland flow discharge and gradient; it is assessed at the slope base to estimate total loss from the land, and delivered to stream channels. 相似文献
8.
神府东胜煤田原生地面放水冲刷试验研究 总被引：4，自引：0，他引：4
神府东胜煤田是我国重要的能源重化工基地,在开发建设过程中造成了严重的人为水土流失,为了分析计算神府煤田弃土弃渣、扰动地面及非硬化路面的新增水土流失量,以本区未经人为扰动的、撂荒的原生地面为自然侵蚀本底值的作用对象,采用野外放水冲刷实验的研究方法,对原生地面的侵蚀产沙规律进行了研究.结果表明径流量、产沙量与放水流量,径流量、产沙量与坡度的关系均呈线性相关,即随着坡度与放水流量的增大,径流量和产沙量也在线性增加.径流量与产沙量之间呈幂函数关系变化,关系式为Ms=0.049W0.93. 相似文献
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水流输沙能力是土壤侵蚀过程极其重要的参数之一,精确计算细沟水流输沙能力可以有效揭示细沟侵蚀过程机理,为建立坡面细沟侵蚀过程模型奠定重要基础。采用细沟水槽试验方法对黄土坡面细沟水流输沙能力变化特征进行研究。结果表明:不同坡度下,细沟水流输沙能力随流量增加而平缓增大,可用幂函数方程很好地描述;不同流量下,细沟水流输沙能力随坡度的增加而增大,可以用指数方程很好地描述;细沟水流输沙能力随流量及坡度变化的因子模型为二元幂函数方程,其中流量对细沟水流输沙能力的影响大于坡度的影响;ANSWERS模型中的输沙能力方程不能用于计算黄土陡坡细沟水流输沙能力。 相似文献
11.
神府东胜煤田原生地面放水冲刷试验研究 总被引：1，自引：2，他引：1
神府东胜煤田是我国重要的能源重化工基地，在开发建设过程中造成了严重的人为水土流失，为了分析计算神府煤田弃土弃渣、扰动地面及非硬化路面的新增水土流失量，以本区未经人为扰动的、撂荒的原生地面为自然侵蚀本底值的作用对象，采用野外放水冲刷实验的研究方法，对原生地面的侵蚀产沙规律进行了研究。结果表明：径流量、产沙量与放水流量，径流量、产沙量与坡度的关系均呈线性相关，即随着坡度与放水流量的增大，径流量和产沙量也在线性增加。径流量与产沙量之间呈幂函数关系变化，关系式为Ms=0.049W0.93。 相似文献
12.
土壤侵蚀过程中坡面流水力学特性及侵蚀动力研究评述 总被引：5，自引：0，他引：5
土壤侵蚀动力过程是水流和土壤两者相互作用的复杂物理过程,而含沙水流是土壤侵蚀的主要动力,深入理解坡面流水力学特征及侵蚀动力是研究土壤侵蚀动力学规律的基础.本文从坡面流水力学特性及侵蚀动力,包括:流速、水深、流态、阻力规律以及坡面流的切应力、冲刷动力、运动能量等多方面对国内外关于土壤侵蚀动力过程研究进行了系统深入的评述,并探讨了研究中存在的问题,重点指出:坡面流作为三维、非恒定非均匀沿程变量流,流动形态千变万化,坡面状况较为复杂,其均匀流理论远不能真实反应自然界复杂地表状况下的水流水力学特性及其变化规律.开展复杂地表的水流运动过程、水力学参数变化规律及坡面侵蚀水动力过程研究是今后土壤侵蚀水动力学研究的重要方向,这对于深入了解土壤侵蚀水动力过程的内在机制、构建物理侵蚀模型具有重要的研究意义. 相似文献
13.
为了方便快速地评估单次径流条件下植被过滤带对污染物氮、磷的净化效果,该文设计了地表径流的模拟放水试验,分析了泥沙与颗粒态污染物的相关性,依据土壤混合层概念简化了土壤污染物的输移,建立了植被过滤带对污染物作用效果的估算模型。结果表明:径流中颗粒态氮、磷含量与泥沙含量有显著相关性(P0.05),据此建立线性相关方程,估算出植被过滤带对颗粒态污染物的净化效果,其86%以上样本的颗粒态氮、磷质量浓度模拟偏差均在±20%之内;溶解态氮、磷的迁移分两部分,即发生于坡面地表径流中和土壤混合层中,分别根据质量平衡原理建立方程对溶解态污染物的迁移进行了模拟,验证得到83%以上样本的溶解态氮质量浓度模拟偏差在±20%之内,67%以上样本的溶解态磷质量浓度模拟偏差也在±20%之内,研究表明,可以基于土壤混合层概念和水文及土壤侵蚀模型对植被过滤带净化效果进行评估。 相似文献
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坡度和流量对崩积体坡面细沟水流输沙能力的影响 总被引：4，自引：3，他引：1
为探究坡度及流量对崩岗崩积体土壤坡面细沟侵蚀输沙能力的影响,精确计算细沟水流输沙能力,建立坡面细沟输沙能力因子模型,以崩岗崩积体土壤为研究对象,进行室内水槽模拟试验研究。结果表明:(1)不同流量条件下,坡面细沟输沙能力随坡度的增大而增大,且增幅随坡度的增加而增大,可用一元线性方程表示;(2)不同坡度条件下,坡面细沟输沙能力随着流量的增大而增大,可用幂函数表示;(3)崩岗崩积体坡面细沟输沙能力因子模型为二元幂函数方程,其中流量(q)和坡度(S)的指数分别为1.054和0.617,流量对细沟输沙能力的影响大于坡度;(4)通过模型对比发现,Wu模型、ANSWERS模型及Zhang模型方程都无法很好地预测崩岗崩积体坡面细沟输沙能力。 相似文献
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基于GRNN的坡面径流输沙能力模型的试验研究 总被引：1，自引：0，他引：1
坡面径流输沙能力是建立土壤侵蚀过程模型的重要水力学参数,研究定量计算坡面径流输沙能力的实用模型具有重要的理论和实践意义.通过室内模拟径流冲刷试验,计算不同坡度和流量条件下的裸地坡面径流输沙能力,利用平均影响值(MIV)方法对影响坡面径流输沙能力的因子进行分析,建立以干密度、能坡、进口流量、出口流量、水力半径、流速为输入,以坡面径流输沙能力为输出的广义回归神经网络(GRNN)模型,并应用Adaboost算法对模型进行优化.验证结果表明,所建模型能够用于对坡面径流输沙能力的模拟预测.与BP神经网络模型进行对比分析的结果表明:在试验训练样本条件下,广义回归神经网络(GRNN)模型的模拟预测结果优于BP神经网络模型;Adaboost算法能够有效减小广义回归神经网络(GRNN)模型的模拟预测误差. 相似文献
16.
黄土区土质道路人工降雨及放水试验条件下产流产沙特征 总被引：3，自引：2，他引：1
为了研究土质路面草本植被降低水土流失的作用,采用室内人工降雨及放水试验的方法比较了裸露路和植物路的产流产沙过程及径流水动力学特征,结果表明：相对于裸露路,不同覆盖度植物路总径流量降低幅度为3.94%～ 25.10%,总泥沙量降低幅度为9.65%～45.69%;在大致相同放水量条件下,植物路的土壤侵蚀速率、径流流速和过水断面单位能量均低于裸露路;植物路的Darcy-weisbach阻力系数和曼宁糙率系数分别是裸露路的2.62～9.00倍和1.74～ 3.53倍;植物路通过降低径流流速、减小过水断面单位能量和增大路面粗糙度及径流阻力起到减轻道路侵蚀的作用。该文为广大土质山坡道路侵蚀防治和植物路铺设提供理论支持。 相似文献
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为深入理解黄土高原干旱半干旱地区复杂地貌条件下流域水沙运移规律。基于垂向混合产流机理和运动波方程，构建分布式流域水文模型，耦合流域土壤侵蚀和泥沙输移过程模拟模块，并考虑梯田对水沙过程的影响，建立适用于黄土高原的分布式流域水沙过程模型。选取黄土高原延河支流西川河流域多年实测场次洪水过程的径流泥沙资料，对模型进行率定和验证。径流模拟的纳什效率系数在0.56以上，平均值超过0.70,模拟次洪过程的峰形、峰值、峰现时间与实测过程具有较好的一致性；侵蚀产输沙模拟精度较低，其纳什效率系数均值率定期为0.79,但验证期仅为0.45,模拟结果整体趋势与实测值较一致，但输沙量模拟峰值比实测值偏低。模型可以较精确地模拟黄土高原流域洪水产汇流过程，但输沙量模拟值偏低，一方面由于产汇流模块的误差传递；另一方面，对重力侵蚀考虑不足。因此，未来模型将考虑滑坡、崩塌等重力侵蚀过程，提升模拟精度和效率，为流域水沙过程模拟与流域综合治理提供有效工具。 相似文献
19.
Despite widespread bench terracing of rainfed hillsides in upland West Java, soil loss rates remain high. This paper reports measurements of sediment yield from terrace risers and beds and from terrace units made during three consecutive rainy seasons. The results demonstrate that soil loss from the terraces occurs in two stages: rainfall‐driven transport by splash and shallow overland flow (wash) from the terrace riser and bed to a central drain is followed by a combination of onward wash transport of fine sediment and entrainment by runoff of coarser sediment deposited in the drain. A model (TEST: Terrace Erosion and Sediment Transport) was developed, describing these processes as a function of vegetation and soil surface cover and the presence of a layer of deposited sediment. The model was calibrated using some of the measured sediment yield data and subsequently tested by simulating the remaining data. The results were satisfactory and modelled fractions of sediment transported by splash, wash and flow‐driven runoff transport generally compared well with observed fractions of fine and coarse particles in eroded sediment from the various plots. 相似文献
20.
土壤分离能力测定的不确定性分析 总被引：8，自引：7，他引：1
土壤分离能力是含沙量为零时坡面径流分离土壤的最大值,是确定细沟可蚀性和土壤临界剪切力的基础,也是土壤侵蚀过程模型推广应用的前提,因此,对其准确测量非常关键。在系统分析野外坡面径流小区无法测定土壤分离能力的基础上,从室内试验水槽的类型与规格、土样采集的代表性、测试样品的长度、扰动程度、初始土壤含水量及土样冲刷时间等方面,系统讨论了它们对土壤分离能力的潜在影响与机制,探讨了土壤分离能力测定过程中的不确定性。对深刻理解土壤侵蚀过程的动力机制、选择合理的土壤分离能力测定方法与试验过程,具有重要的指导意义。 相似文献