基于动力网络的分布式运动波汇流模型

在传统的运动波汇流模型基础上，建立了基于动力网络的分布式运动波汇流模型。该模型将分布式水文模型中的产流单元与河网组合建立成无尺度网络模型，汇流计算分成节点汇流与网络汇流两阶段完成，根据积水面积的不同分成坡面汇流与河道汇流。应用结果表明：所建模型的汇流汁算更加接近流域的实际汇流过程，理论更合理，并充分利用了DEM所提供的地形地貌信息，模拟效果较好。     

异参离散广义Nash汇流模型及应用

在广义Nash汇流理论基础上发展而来的离散广义Nash汇流模型,概念明确,结构简单,便于应用,但模型中各线性水库的调蓄参数K是相同的,致使其在河道地形(坡降和断面形状)变化较大河段应用时有其局限性。通过引入异参瞬时单位线及其S曲线,在离散广义Nash汇流模型概念解析的基础上,推导得出了异参离散广义Nash汇流模型,从而丰富了现有广义Nash汇流理论,扩大了离散广义Nash汇流模型的适用范围。实例分析表明,由于考虑了参数K的空间异质性,异参离散广义Nash汇流模型可以进一步提高河道洪水的模拟精度。     

河段汇流及抵偿河长的计算与分析

地表径流的汇流包括坡面汇流及河网汇流两个阶段,总称为流域汇流。坡面汇流是分析净雨经过坡面调蓄如何进入河网的,实质上就是将净雨在时程上进行初次再分配后输送补给河网,它是流域中净雨汇集并注入河网的必然过程。河网汇流是经河网的调蓄作用,再次将净雨进行分配后到达流域出口断面的过程,它是水流运动在新条件下的继续,也是聚集坡面水流运动后所导致的必然结果。小流域坡面汇流对出口断面的径流过程起主导作用,故解决小流域汇流问题是以研究坡面汇流为基础的。坡面汇流引起的径流,在时程上的初次分配对出口断面的径流过程     

模拟波浪运动的三维自由表面流动数值模型

基于Navier-Stokes方程建立了三维自由表面流动数值模型来模拟波浪运动.模型中Navier-Stokes方程的求解采用两步投影法,计算域的空间离散采用交错网格.采用满足自由表面运动学边界条件的水位控制方程来计算自由表面.通过数值结果与解析解的比较,验证了本文建立的三维自由表面流动数学模型可以精确的模拟线性色散波以及孤立波沿平底坡和非平底坡的传播.     

基于网格新安江模型的汇流方法研究

为使网格新安江模型更好应用于无资料地区洪水模拟及预报,文章采用网格水滴汇流方法构建网格新安江模型的汇流部分,以湿润地区屯溪流域为研究流域,将网格水滴模型与扩散波汇流模型及马斯京根汇流模型对比验证其模拟精度,并将网格水滴模型应用于半湿润半干旱地区东湾流域验证其适用性。结果表明,采用网格水滴汇流方法的洪水模拟过程在屯溪流域的模拟精度与其他2种方法基本相当,均可以达到甲级预报精度;同时在半湿润半干旱地区东湾流域的应用达到乙级预报精度。网格水滴汇流方法具有一定适用性。     

线性汇流系统的离散型通用模型

目前,求解线性汇流系统的数学模型,多数为连续型,但水文系统中的变量,常处理为离散形式,且难以用初等函数描述,这一矛盾限制了连续型数学模型的应用范围。现行解决问题的办法,主要是将连续型模型离散化,或用离散型模型求数值解。 近年来,Z变换在求解离散变量序列运算问题中的作用,已开始为水文界所注意。本文建议了一个线性汇流系统的通用模型,并提出了用Z变换作该模型分析和识别的方法。     

基于DEM的黄土丘壑区动力学流域水沙数学模型应用研究——以黄河中游两个典型小流域为例

该文以黄土丘陵沟壑区典型小流域—岔巴沟流域为研究对象,首先采用地理信息系统(GIS)对坡度和土地利用方式等侵蚀产沙环境因子提取分析,提出基于网格的超渗产流模型和基于运动波理论的栅格型坡面汇流模型,然后采用Preissmann四点隐式差分进行方程的离散求解。另外根据研究区地形及地貌特点将其分为梁峁坡、沟谷坡和沟槽三种垂直分带侵蚀单元,采用力学分析建立其侵蚀产沙公式和分布式坡面流运动波模型进行耦合求解。本模型在岔巴沟流域1970~2001年17场水沙过程的模拟和验证结果表明:产汇流、产沙计算平均确定性系数分别为0.69、0.58。杏子河流域验证结果也表明该模型对黄丘区水土流失时空过程的模拟计算具有一定精度,模型预测成果可为黄土高原水保规划和生态建设等提供更为精细和科学的决策依据。     

基于Nash 瞬时单位线法的渗透坡面汇流模拟

基于Nash瞬时单位线法,结合Horton土壤入渗经验模型,并考虑植被对降雨的截流作用,建立了渗透坡面汇流计算的数学模型。以矩形坡面为研究对象,基于其汇流时间-面积特性,结合等流时线法,推导建立了Nash瞬时单位线参数n、K的确定方法。其中,参数n的值为1.0,K的值与坡面汇流时间相等,相当于单一线性水库。应用本文建立的模型,对林地渗透坡面降雨径流进行计算,并与实测值进行比较。结果表明,计算值与实测值的变化趋势基本吻合,初步验证了本文方法的合理性。     

基于Nash瞬时单位线法的渗透坡面汇流模拟

基于Nash瞬时单位线法,结合Horton土壤入渗经验模型,并考虑植被对降雨的截流作用,建立了渗透坡面汇流计算的数学模型。以矩形坡面为研究对象,基于其汇流时间-面积特性,推导建立了Nash瞬时单位线参数n、K的确定方法。其中参数n的值与坡面汇流时间-面积曲线指数相等,K的值与坡面汇流时间相等。应用本文建立的模型,对林地渗透坡面降雨径流进行计算,并与实测值进行比较。结果表明,计算值与实测值的变化趋势基本吻合,初步验证了本文方法的合理性。     

流域产,汇流研究的进展及展望

流域产、汇流和河道洪水计算是水文预报的重要组成部分。本文概述了我国自５０年代以来在流域产流研究、流域汇流研究和河道洪水计算方面所取得的进展，展望了流域汇流研究的三个发展方向：即物理分析途径方向、系统分析方向和随机水文学方向。认为我国近几年来在流域汇流研究方面主要有三点进展：即广泛地采用了线性系统分析方法，多种途径研究了非线性汇流计算，开发了汇流数值试验及随机汇流模型的研究。     

Numerical Models for the Simulation of Overland Flow in Fields Within Surface Irrigation Systems

Discharges in a network of drainage ditches generated by intense rainfall are influenced by overland flow dynamically interacting with infiltration. Therefore a detailed estimation of the overland flow, especially in agricultural fields prepared for surface irrigation, is essential to the design of drainage ditches. In order to simulate overland flow, which in that case may be considered unsteady and one dimensional, numerical models were developed based on the numerical solution of the Saint-Venant equations, externally coupled with the Green-Ampt equation to account for the dynamic interaction between surface flow and infiltration. The numerical solution of the Saint Venant equations in their complete form (dynamic model) and in the simplified forms of the diffusion (diffusion model) and the kinematic wave equations (kinematic model) was obtained by applying the MacCormack explicit computational scheme. Overland flow models’ simulations were conducted in order to study the effect of the soil surface parameters on the hydrographs at the downstream end of the fields, as well as the accuracy of the diffusion and kinematic equations. It was found that the kinematic wave equations were unable to describe overland flow, while the diffusion model results were close to the results of the dynamic model.     

地下水流与河网水流的耦合模型

从河道水流一维不稳定流(扩展的圣维南方程组)有限差分的递代方程和地下水的有限元数值方法出发，通过河道四周地下水流与河道水流的交换流量把两个模型数值计算的矩阵方程从理论上耦合起来.理想水文流域系统的计算结果表明，模型的设计是合理的     

草被覆盖度下坡面流流速变化及缓流机制研究

坡面薄层水流是黄土区土壤侵蚀发生的直接动力条件,探究植被覆盖条件下坡面流水动力学特性及缓流机制,有助于揭示土壤侵蚀发生的水动力学机理。在水槽坡度为12°条件下,通过9个草被覆盖度、7个流量的组合试验,研究了不同植被覆盖度下坡面水流流速变化和缓流机制。结果表明:坡面流流速随着覆盖度的增加整体呈减小的趋势;缓流系数随覆盖度的增加呈先增大后减小的变化规律,当覆盖度大于47.66%时,缓流系数随覆盖度的增加显著减小;以覆盖度47.66%为临界值,高、低覆盖度下缓流系数随雷诺数的变化规律有所不同。最后,建立了模拟草被下的坡面流流速和缓流系数拟合公式,验证结果表明,拟合公式精度较高,可为建立土壤侵蚀预报模型提供参考。     

Kinematic Wave Theory of Overland Flow

Kinematic wave (KW) theory is widely applied for modeling overland flow. The theory is comprised of (1) continuous waves, (2) formation of shocks, and (3) propagation of shocks. This paper revisits the KW concept for overland flow from fluid mechanical and mathematical points of view. Then, it develops mathematical formulations of overland flow, based on the classification of overland flow problems and the influence of storm movement and areal coverage. Depending on the class of overland flow problems, the mathematical formulation involves free boundary problems that are not known beforehand and must be solved for along with the solution of the problem. Finally, the validity of the KW concept is revisited and the accuracy of the KW approximation can be expressed by Riccati equation that describes the error for the whole hydrograph.     

平原河网水动力模型及求解方法探讨

参考国内外有关资料 ,根据河网非恒定流水动力模型的控制方程组和汊点衔接条件 ,建立平原河网水动力节点 河道模型。介绍用特征线法 ,有限体积法和有限差分法中的直接解法、分级解法、汊点分组解法、矩阵标识法、非线性方法等求解的基本思路。对比单元划分模型、混合模型以及人工神经网络模型等平原河网水动力模型 ,分析各个模型的优缺点 ,结果表明 ,节点 河道模型原则上可以求解任何水网的水力参数 ,单元划分模型仅适用于河道流速时空变化不大的情况 ,人工神经网络模型的验证比较困难。指出改进和设计计算方法、应用向量运算和并行算法、数值模拟可视化、数值计算模型软件化是河网数值模拟的主要发展方向     

A Distributed Kinematic Wave–Philip Infiltration Watershed Model Using FEM,GIS and Remotely Sensed Data

Distributed rainfall–runoff modeling is very important in the water resources planning of a watershed. In this study, a kinematic wave based distributed watershed model which simulates runoff on an event basis has been presented here. The finite element method (FEM) has been used to simulate the overland runoff and channel flow. Philip model has been used for the infiltration estimation. To find out runoff at the outlet of the watershed, both overland flow and channel flow models are coupled. The coupled model has been applied to a typical Indian watershed. Remotely sensed data has been used to obtain the land use (LU)/land cover (LC) for the watershed. Slope map of the watershed has been obtained using geographical information systems (GIS). The grid map of the watershed which contains overland flow elements connecting to channel flow elements has been prepared in GIS. The elemental input files such as slope and Manning’s roughness are prepared using the GIS and are directly used in the model. The model has been calibrated using some of the rainfall events and validated for some other events. The model results are compared with the observed data and found to be satisfactory. A sensitivity study of the infiltration parameters, overland and channel flow Manning’s roughness and time step has also been carried out. The developed model is useful for the simulation of event based rainfall–runoff for small watersheds.     

坡面流阻力研究进展

坡面流阻力的研究对了解坡面流水流特性、汇流过程、土壤侵蚀和坡面产沙机理都非常重要。本文分5个方面总结了坡面流阻力研究的最新进展:(1)坡面流阻力系数与雷诺数的关系;(2)光滑床面上的坡面水流阻力;(3)粗糙床面上的坡面水流阻力;(4)降雨对坡面流阻力影响的研究;(5)坡面流阻力的计算模型。综合前人研究发现,阻力系数与雷诺数在不同的条件下呈正相关或负相关关系;用叠加法计算不同条件下的坡面流阻力有其合理的一面,也有不足之处;粗糙动床条件下的坡面水流阻力计算模型更接近实际情况。最后,本文指出了当前坡面流阻力研究存在的主要问题和未来需要突破的主攻方向。     

Calculation of watershed flow concentration based on the grid drop concept

The grid drop concept is introduced and used to develop a micromechanism-based methodology for calculating watershed flow concentration. The flow path and distance traveled by a grid drop to the outlet of the watershed are obtained using a digital elevation model （DEM）. Regarding the slope as an uneven carpet through which the grid drop passes, a formula for overland flow velocity differing from Manning＇s formula for stream flow as welt as Darcy＇s formula for pore flow is proposed. Compared with the commonly used unit hydrograph and isochronal methods, this new methodology has outstanding advantages in that it considers the influences of the slope velocity field and the heterogeneity of spatial distribution of rainfall on the flow concentration process, and includes only one parameter that needs to be calibrated. This method can also be effectively applied to the prediction of hydrologic processes in un-gauged basins.     

连续急流弯道水流泥沙的数值模拟

建立了具有连续急流弯道河流平面水流、泥沙数学模型 ,并采用有限差分法对方程进行离散求解。运用该模型对山西省阳泉市桃河治理河段的水流泥沙情况进行计算 ,得到的数值模拟结果与模型试验结果基本相符 ,表明该模型在工程上具有一定的实用价值     

Longitudinal variations of hydraulic characteristics of overland flow with different roughness简

The evolution of the overland flow velocity along the distance downslope on smooth and granular beds in different cases is investigated by means of the electrolyte tracer via flume experiments.The results demonstrate that a non-uniform flow regime and a uniform flow regime exist in the development process of the overland flow.Owing to the different attributes of beds’roughness,the position of those zones with different flow regimes varies correspondingly:(1)the overland flow on granular beds enters into the uniform regime much sooner,additionally,the roll waves tend to appear because of the presence of the proper flow resistance imparted by the roughness(coarse sands),and large slopes(20o and 25o)which makes the flow velocities and depths to undulate spatially.Furthermore,the flow resistance of the overland flows with different roughness elements,that is the non-sands,the fine sands and the coarse sands,is calculated.A quadratic interpolation method of the third order accuracy is employed in the calculation of the longitudinal flow resistance.The results show that it is rational to use the bed slope to approximate the hydraulic energy slope over a relative small roughness(the present roughness),however on the other hand,if the mean flow velocities and depths rather than the local parameters are used to calculate the flow resistance,a considerable error will be induced within the non-uniform regime of the overland flows,including the acceleration zone and the roll-wave zone.