分布式水文模型软件系统MWEasyDHM 简介

本文介绍了分布式水文模型EasyDHM模型的软件系统MWEasyDHM,主要由4个部分组成：（1）面向水文分析的通用GIS软件;（2）前处理模块;（3）模拟模块;（4）后处理模块。其中面向水文分析的通用GIS软件以开源GIS软件MapWindow为基础开发,并包括了其他模块所涉及的基本GIS功能;前处理模块包括基于DEM的水文分析组件,模型参数推求模块和降水量、气象数据插值模块;模拟模块提供了实时计算功能,能实时查看模拟结果;模型后处理模块包括了模型参数自动识别、运算结果统计分析及以表格、图表等方式对模拟结果的展示。MWEasyDHM的开发解决了分布式水文模型快速建模及率定的难题,并为将来升级开发及大范围推广应用奠定了基础。     

城市雨水管理模型中关键问题探讨(三)——低影响开发模拟

低影响开发(LID)模块是海绵城市建设过程中重要的工程措施之一。城市雨水管理模型(SWMM)中提供了多种LID模块的模拟方法,同时也是其他商业软件LID模拟的主要方法。系统介绍模型中LID模块类型及各个参数的意义,重点分析了各个模块的模拟计算原理及计算方法,提出了各个参数的建议值。     

地下水污染健康风险模拟预测评估中参数的敏感度分析

随着地下水污染健康风险评估逐渐被重视,其风险的影响程度和发展趋势也越来越被关注,因此解析解模拟预测评估地下水污染健康风险也逐渐被应用。本文旨在研究解析解模型对污染物健康风险模拟的敏感度,为该方法更广泛的应用提供依据。选取解析解模型中的渗透系数(K)、纵向弥散度(αx)、污染物有机碳分配系数(Koc)和半衰期(t1/2)4个参数,在其他参数不变的情况下,依次改变各参数的值并进行解析解计算,记录对应的参数值与模拟结果,绘出模拟预测值与各个分析参数的变化曲线,分析解析解对各个参数的响应程度,从而为处理不确定因素提供依据。     

潜流式人工湿地的数值模拟与参数率定

以沈阳辉山明渠河口潜流式人工湿地为例,利用数值模拟预测了该湿地的运行效果。采用多孔介质水流与溶质运移耦合模型,通过对湿地模型的概化与处理,利用FEFLOW软件针对潜流基质层的水流和溶质扩散进行数值模拟,通过敏感度分析确定基质层的孔隙度、渗透系数、弥散系数和吸附降解系数为影响污水处理效果的敏感参数,并通过参数率定对所建立的湿地模型进行了模拟预测,结果证明所构建的湿地模型的预测值与观测值拟合程度较好。可为潜流式人工湿地设计中运行效果预测及参数设定提供一种新的有效方法。     

潜流式人工湿地的数值模拟与参数率定

摘要：本文以沈阳辉山明渠河口潜流式湿地为例，探讨了利用数值模拟预测湿地运行效果以及参数率定的方法。采用多孔介质的水流与溶质运移耦合模型，通过对湿地模型的概化与处理，利用FEFLOW软件针对潜流基质层水流和溶质扩散进行了数值模拟，通过敏感度分析确定基质层的孔隙度、渗透系数、弥散系数和吸附降解系数为影响污水处理效果的敏感参数，并通过参数率定对所建立的湿地模型进行了模拟预测，结果证明所构建的湿地模型的预测值与观测值拟合程度较好，从而为潜流式人工湿地设计中运行效果预测及参数设定提供了一种新的有效方法。     

改进剑桥土蠕变模型分析

基于黏弹塑性理论，在改进剑桥模型（ＭＣＣ）的基础上，引入与荷载施加速率相关系数，提出了改进剑桥蠕变模型（ＭＣＣＣ），该模型可以用于模拟土体参数随荷载作用时间、以及荷载加载速率的变化关系。通过对典型加载条件下土体受力状态的模拟，并与ＭＣＣ模型的结果进行对比分析，结果显示ＭＣＣＣ模型可以描述土体的蠕变行为，合理反映土体随加载速率和时长的动态响应规律，是一种可以用于评价土体中具有时间依赖性的参数对工程地基稳定性影响的简单实用模型。     

基于WD-COA-LSTM模型的月降水量预测

为进一步提高月降水量预测精度,提出了基于小波分解（WD）和郊狼优化（COA）算法的长短期记忆神经网络（LSTM）降水量预测模型（WD-COA-LSTM）。首先用小波分解对时间序列进行预处理,消除序列的非平稳性,得到1个低频序列和3个高频序列;然后通过郊狼优化算法对神经网络（LSTM）模型进行参数优化;最后将各子序列预测值叠加得到月降水量预测值。将提出的模型应用于洛阳市栾川县白土镇和洛宁县故县镇两个雨量站的月降水量预测中,并与LSTM、COA-LSTM、WD-LSTM模型预测结果进行对比。结果表明：提出的WD-COA-LSTM模型的预测精度最高,说明小波分解和郊狼优化算法能有效加强LSTM模型预测的精度和泛化能力,为月降水量的预测提供了一种新的途径。     

深圳鹅颈水流域SWMM模型参数敏感性分析及率定研究

以深圳市鹅颈水流域为研究区域搭建SWMM模型,在3场不同强度降雨条件下模拟该区域的水文水质。同时,采用修正摩尔斯(Morris)筛选法对模型水文水质参数进行敏感性分析,并以此结果对模型参数进行率定。研究结果显示:水力模块中参数敏感性的大小依次为不渗透性(imperv)、宽度(width)和坡度(slpoe);水质模块中最敏感的参数为冲刷指数(exponent);经敏感性分析模型率定结果较好,率定误差检验系数ENS为0.634~0.861,R2为0.698~0.96。     

丁坝绕流流场及局部冲刷三维数值模拟研究

精确模拟丁坝附近流场信息,预测冲刷形态对丁坝的设计和安全运行具有重要的意义。本文采用一种基于多相流模式的悬移质输沙与传统推移质输沙相结合的模型模拟丁坝局部流场与冲刷过程,而河床变形则通过填充层体积份数的变化来模拟,VOF法处理自由面。泥沙冲刷侵蚀模型主要分为三个模块:悬移质漂流模块、泥沙挟带模块以及推移质输运模块,通过模拟在水流作用下的泥沙运动来预测泥沙侵蚀、对流扩散以及沉积等过程,同时考虑床面坡度对泥沙输运以及临界希尔兹数的影响。模拟得到了丁坝附近局部流场、地形冲淤变化以及冲刷坑形态等,并把计算结果与试验资料进行了对比分析,二者吻合较好,证明该模型能够很好地反映丁坝附近流场信息和床面变形特征。     

一种高效的SWAT模型参数自动率定方法

本文分析了SWAT模型和PSO算法的原理,将PSO算法引入SWAT模型中,构建了新的SWAT模型参数自动率定模块,通过在天津蓟运河流域实例研究,发现该方法率定精度较高,收敛速度快,运行结果稳定,整体率定效果优于模型自带的参数率定模块。如果用改进后的模块在Linux平台开展自动率定,可以使模型自动率定效率提高到当前水平的7倍,适用于大型流域或长时间系列模拟。而PSO算法作为一种通用的优化算法,可广泛用于各种水文模型的参数率定。     

基于BP神经网络的HEC-RAS二维模型糙率参数自动率定

水面宽阔河段、洪泛区和潮汐河口段的水文及水动力学计算模拟多采用二维模型,然而因模型复杂的非线性映射关系常导致参数率定效率和精度不高,甚至出现"异参同效"问题。为此,提出一种应用BP神经网络自动率定二维模型糙率参数的方法。以海南昌化江入海口段为计算实例进行数值检验,结果表明:编写的Python程序能够准确率定HEC-RAS二维模型实例各糙率分区的糙率参数,各糙率分区的率定糙率值均在参数取值范围内,且均在观测糙率值±0.011内,未出现"异参同效"现象;水位率定计算误差满足设定允许误差要求,设定允许误差0.20 m、0.15 m和0.10 m的平均率定计算误差小于0.10 m,设定允许误差0.05 m的平均率定计算误差接近0 m;设定允许误差为0.15 m时,率定程序的运算效率最高。选用海南201409号台风"威马逊"时期的昌化江实测资料进行验证,证明该方法有效可靠,能够实现HEC-RAS软件二维模型糙率率定功能,可推广应用于其他模型参数率定。     

饱和-非饱和土壤中吸附性溶质水动力弥散实验研究

本文通过室内土柱对轻壤土和重壤土饱和、非饱和水动力弥散实验，得到了吸附性溶质水动力弥散参数的计算方法。根据一维饱和弥散实验结果，由相应的解析解，用简化计算方法求得饱和水动力弥散系数Dsh和阻滞因子R；对于一维非饱和弥散实验，在分析溶质的水动力弥散理论的基础上，推导出求解非饱和土壤水动力弥散系数Dsh(θ)的计算公式。     

Parameter Identification for a Slug Test in a Well with Finite-Thickness Skin Using Extended Kalman Filter

Yeh and Chen (J Hydro 342(3?C4):283-294, 2007) integrated a slug test solution for a well having a finite-thickness skin with the simulated annealing (SA) to determine the hydraulic parameters of the skin zone and formation zone. Some results obtained in positive-skin scenarios are however not accurate if compared with the target values of the parameters. This study first employs the sensitivity and correlation analyses to quantify the relationship between two normalized sensitivities and analyze the resulting errors in parameter estimates. It is found that the inaccuracy in parameter estimates can be attributed to following two problems: (1) the normalized sensitivities of the skin thickness and hydraulic conductivity are highly correlated and (2) the SA algorithm is very sensitive to round-off error in well-water-level (WWL) data. A parameter identification approach is thus developed based on the extended Kalman filter (EKF) coupled with the solution used by Yeh and Chen (J Hydro 342(3?C4):283-294, 2007) to determine the parameters in six positive-skin scenarios where the parameters were not accurately determined before. We show that previous two problems can be overcome by the proposed approach because it is designed to account for uncertainties of measurements. Moreover, the EKF can save 99.8% and 99.9% computing time when compared with the results using the SA in analyzing 20 WWL data and 47 WWL data, respectively.     

NUMERICAL STUDY ON THE PURIFICATION PERFORMANCE OF RIVERBANK

During the rain time, the runoff infiltrates into the riverbank through the collecting gutter and slope surface. The city runoff is generally polluted by organic, oil, heavy metal particulates, etc. The pollutants moving with the water through the riverbank experience advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptaking processes. In this article, a mathematical model was developed to simulate the performance of pollutant removal of the riverbank. The model took those main mechanisms into account. The modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The NH3-N and TP were considered in the present model. The mathematical model was descritized with a finite element numerical model, which was applied to two types of model riverbanks. In the model test, the hydraulic loading was assumed to have the intermittent pattern simulating the storm runoff of certain return period, and the values of the rainfall runoff and concentrations of the NH3-N and TP were taken from the model test. The computed overall removal rates for the NH3-N and TP in 6 cases are in the range of 88%-98%, 87%-97%, respectively. The differences between the computed and tested overall removal rates for the NH3-N and TP are less than 5%. The time-varying oscillation pattern of the concentrations of the NH3-N and TP were rationally simulated, which shows that the model presented in this article can be used to assess the purification performance of the riverbank constructed with sand or soil.     

参数率定方案对水温数值模拟结果的影响

建立了立面二维水动力-水温模型,运用建库前天然河道及邻近区域同类型水库两组不同实测资料对模型进行参数率定。根据这两组计算参数分别模拟了验证时段内D水库水温分布,以及A水库库区水温变化过程。数值模拟结果表明,在其他条件保持一致的情况下,天然河道及邻近区域同类型水库资料均可用于数值模拟参数的率定,将两组验证参数用于实际计算时,所得结果表现出相同的规律,但具体数值存在一定差异。分析认为,邻近区域同类型水库资料验证更符合实际情况,故在此类水库水温的数值模拟中,应尽量选择邻近区域同类型水库资料作为验证资料,若在条件不足的情况下,相关的天然河道资料也可以作为参考。     

PARAMETER IDENTIFICATION FOR MODELING RIVER NETWORK USING A GENETIC ALGORITHM

The simulation of a one-dimensional river network needs to solve the Saint-Venant equations, in which the variable parameters normally have a significant influence on the model accuracy. A Trial-and-Error approach is a most commonly adopted method of parameter calibration, however, this method is time-consuming and requires experience to select the appropriate values of parameter. Consequently, simulated results obtained via this method usually differ between practitioners. This article combines a hydrodynamic model with an intelligent model originated from the Genetic Algorithm (GA) technique, in order to provide an intelligent simulation method that can optimize the parameters automatically. Compared with current approaches, the method presented in this article is simpler, its dependence on field data is lower, and the model accuracy is higher. When the optimized parameters are taken into the hydrodynamic numerical model, a good agreement is attained between the simulated results and the field data.     

WEP模型参数自动优化及在汉江流域上游的应用

本文将全局参效自动优化算法-复形进化算法,引入WEP-L模型,并成功应用于汉江上游流域.通过复形进化算法参数自动优化,可找到WEP-L模型的一套较优的参数.同时,为比较不同目标函数对参数敏感性与自动率定的影响,分别对8种目标函数进行了参数敏感性分析及自动率定.结果显示,如果以水量误差和纳什效率系数为评价标准,排序后的残差平方和及其变化形式的效果较好.WEP-L模型参数敏感性分析及参数自动化率定的实现,可提高WEP-L模型参数率定的科学性和客观性,从而方便WEP-L模型的推广与应用.     

A comparison of various uncertainty models: An example of subsurface contaminant transport

Groundwater resources are under increasing threat of contamination and wasteful use in many parts of the world. Groundwater flow and integrated contaminant transport models are commonly used to predict the fate of contaminants in the subsurface environment. However, the lack of reliable data and complexity of the natural environmental systems, the predictions are subjected to large uncertainties. For reliable decision-making, these contaminant transport models are required to explicitly consider associated uncertainties in their parameters. This paper aims to compare the results of four common uncertainty models using an example of contaminant transport in groundwater. The research employed an advection–dispersion equation (ADE) to describe the transport of a contaminant in groundwater. For simplicity, two parameters – dispersion coefficient and velocity – were considered in the uncertainty analysis. Fuzzy set theory, one- and two-dimensional (1-D and 2-D) Monte Carlo simulations, and Probability Box (P-Box) methods were investigated. The cumulative distribution functions generated from these analyses were compared to evaluate the capabilities of these methods. The comparison showed that P-Box method provides a more comprehensive analysis with lesser assumptions as compared to other methods, and also found to be more pragmatic way to describe and propagate uncertainties in complex environmental systems. Furthermore, execution time required to perform uncertainty analysis using P-Box method is comparatively much less than 2-D Monte Carlo simulations.     

Z坐标系下分层三维水流数学模型研究

建立了z坐标系下分层三维水流数学模型,避开了在地形突变σ变换下水平压力梯度计算较大的困难.在任意三角形网格中,通过剖开算子法,将方程剖分为不同子算子,用各自适应的数值解法进行求解.潜坝及斜槽水流的计算结果与实验结果吻合较好,而基于σ变换的Delft3D模型计算值与试验值相差较大,因此本文的z坐标分层数学模型可以用来计算包括地形突变的三维水流,并具有较高的精度.