Calibration of HEC-RAS Model on Prediction of Flood for Lower Tapi River, India

Channel roughness is a sensitive parameter in development of hydraulic model for flood forecasting and flood inundation mapping. The requirement of multiple channel roughness coefficient Mannnig’s ‘n’ values along the river has been spelled out through simulation of floods, using HEC-RAS, for years 1998 and 2003, supported with the photographs of river reaches collected during the field visit of the lower Tapi River. The calibrated model, in terms of channel roughness, has been used to simulate the flood for year 2006 in the river. The performance of the calibrated HEC-RAS based model has been accessed by capturing the flood peaks of observed and simulated floods;and computation of root mean squared error (RMSE) for the intermediated gauging stations on the lower Tapi River.

HEC-RAS Model for Mannnig’s Roughness: A Case Study

Channel roughness is considered as the most sensitive parameter in development of hydraulic models for flood forecasting and flood inundation mapping. Hence, it is essential to calibrate the channel roughness coefficient (Mannnig’s “n” value) for various river reaches through simulation of floods. In the present study it is attempted to calibrate and validate Mannnig’s “n” value using HEC-RAS for Mahanadi Riverin Odisha (India). For calibration of Mannnig’s “n” value, the floods for the years 2001 and 2003 have been considered. The calibrated model, in terms of channel roughness, has been used to simulate the flood for year2006 inthe same river reach. The performance of the calibrated and validated HEC-RAS based model has been tested using Nash and Sutcliffe efficiency. It is concluded from the simulation study that optimum Mannnig’s “n” value that can be used effectively for Khairmal to Barmul reach of Mahanadi Riveris 0.029. It is also verified that the peak flood discharge and time to reach peak value computed using Mannnig’s “n” of 0.029 showed only an error of 5.42% as compared with the observed flood data of year 2006.

Calibration of HEC-RAS Model for One Dimensional Steady Flow Analysis—A Case of Senegal River Estuary Downstream Diama Dam

The Sahelian regions have experienced a drought that has made them vulnerable to hydro-climatic conditions. Strategies have been developed to reduce this vulnerability. The governments of Senegal, Mauritania, Mali and Guinea have created the Organization for the development of the Senegal River (OMVS in french) with the aim of realizing large hydraulic installations. This resulted in the construction of the Diama and Manantali dams in the Senegal River Basin. The first aims to stop the saline intrusion, the second to regulate the flow of the river, to allow the irrigation of agricultural perimeters, and to produce electrical energy. The impoundment of the Diama dam has modified the hydraulic behavior of the estuary. The purpose of this study is to carry out the hydraulic modeling of the estuary of Senegal river downstream of the Diama Dam in transient mode by the HEC-RAS software. Two geometric models were constructed on the basis of a digital terrain model (DTM) using the Arc-GIS and HEC GeoRAS soft wares after processing the collected topographic data. The first geometric model, of which the areas of Senegal river downstream Diama Dam have been represented by cross-section, is one-dimensional. The second one is also one dimensional;in this model, the area of the Senegal River estuary downstream Diama Dam is introduced as water storage zones. The components of these models are the stream sections, lateral links, and storage areas. The flood hydrograph downstream Diama Dam is introduced as conditions at the upstream limits of the models while the tidal is introduced as a downstream condition. After the stability and calibration, the results given by HEC-RAS simulations are the variations of the water levels, the temporal variations of the flow rates for each section, the maximum flow velocities and the propagation times of the flood waves. The analysis and comparisons of these results strongly suggest using HEC-RAS issues as a decision-making tool helping to manage floods during times of crisis.

Calibration of Channel Roughness for Mahanadi River, (India) Using HEC-RAS Model

Channel roughness is the most sensitive parameter in development of hydraulic model for flood forecasting and flood plane mapping. Hence, in the present study it is attempted to calibrate the channel roughness coefficient (Manning’s “n” value) along the river Mahanadi, Odisha through simulation of floods using HEC-RAS. For calibration of Manning’s “n” value the flood of year 2003 has been considered. The calibrated model, in terms of channel roughness, has been used to simulate the flood for year 2006 in the same river reach. The performance of the calibrated and validated HEC-RAS based model is tested using Nash and Sutcliffe efficiency. It is concluded from the simulation study that Mannnig’s “n” value of 0.032 gives best result for Khairmal to Munduli reach of Mahanadi River.

Rainfall-Runoff Simulation and Modelling Using HEC-HMS and HEC-RAS Models: Case Study Tabuk, Saudi Arabia

Flooding regimes in arid regions are heavily influenced by climate change, water shortage, water regulations, and increased water demands. The low amount of annual precipitation due to the desert climate may lead to false estimations of flooding hazards. This study analyzed flash floods caused by short-intense rainstorms. The objective of this study was to determine flood risk related to identified precipitation depths. The project quantized the runoff corresponding to different design storms and used hydraulics and geospatial data to determine flood elevations. The study constructed hydrologic and hydraulic models to quantify flood hazards in the adjacent area of Wadi Abu Nashayfah. Peak discharges for the wadi were computed by using observed rainfall data, and the output of this process was applied to compute water surface elevations within the flow channel. At upstream, there is a high potential of flooding when Wadi Abu Nashayfah receives a minimum of 25 mm of rain which generates 40.60 m3/s of peak discharge, thus, at this point the stream will overtop its banks and risking the adjacent area. In the second case, flow will overtop its banks when the channel receives at least 35 mm of rain and peak discharge level to 67.20 m3/s. While flow will reach bank full point if wadi Abu Nashayfah receives 10.00 mm of rain and generates 14.80 m3/s of streams downstream. The depth of precipitation at which the channel was overtopped was determined in several locations. The predicted overtopping was compared to historic events with good agreement.

基于ENVI+HEC-RAS的苏北运河生态修复方法及改善效果研究

鉴于生态修复对维持河流健康生命十分重要,以提升植被覆盖度与水质为目标,对苏北运河进行生态修复。基于2018年研究区Landsat8遥感影像数据,运用ENVI软件对苏北运河全河段的土地利用情况进行处理分析,并在增加上游生态来水的情况下,使用HEC-RAS软件对泗阳新一水厂断面的COD水质指标浓度进行模拟。结果表明,苏北运河全河段植物覆盖度最大可提升至59.84%,且Kappa系数结果均大于0.6,精度符合要求;COD水质指标浓度在5、10、12月达到Ⅱ类水标准,其余月份较调控前均已达到Ⅲ类水标准,可见在增大生态来水作用下,运河水质得到提升。

基于HEC-RAS的沥青混凝土心墙坝溃坝洪水过程模拟分析

大坝溃口发展过程模拟是开展溃坝洪水分析的基础,不同坝型溃口发展过程不同,溃口流量(下泄洪水)过程差异很大。文章通过对某水电站沥青混凝土心墙坝溃口形式的研究,采用HEC-RAS(Hydrologic Engineering Centers-River Analysis System)软件进行溃坝洪水模拟,旨在探讨沥青混凝土心墙坝在水库溃坝风险中的关键因素,着重考虑沥青混凝土心墙对溃口发展的影响。结果显示,初始运行水位、洪峰流量的重现期、溃坝历时及泄水建筑的泄流方式对溃口流量产生显著影响。研究成果为未来水利工程的安全可靠建设提供了科学依据。

基于MIKE11和HEC-RAS的模拟水面线比较及敏感性分析

应用HEC-RAS和MIKE11模型对淮河踅孜镇到淮滨站河段进行水面线计算,采用相同河道、断面、流量数据、下游水位流量关系、糙率等,推算水面线并与真实数据对比,计算了模型的精度,并对模型中涉及的主要水文参数——河道坡度和河道糙率进行敏感性分析。计算结果表明,MIKE11水动力模型推算的水面线精确度更高,其水位结果也略高于HEC-RAS模型,更加适用于研究区,经计算,MIKE11模型对糙率更为敏感,两个模型对河道比降均不敏感。

基于SWMM耦合HEC-RAS的人工建设水网防洪排涝模拟研究

对新建城区的水文、水动力过程进行准确模拟分析是人工水网规划建设及新建城区内涝防治的关键。应用SWMM分布式水文模型耦合HEC-RAS二维水动力SWE-ELW模型,对安徽省阜阳市城南水网进行模型模拟及防洪排涝分析。结果表明,SWMM模型中计算参数更多,排涝模数随汇水分区面积增大而减小,且与规划泵站排涝模数接近,计算结果更为合理。城南水网排涝标准30年一遇工况下,城南水网水系汛期最高水位为27.89 m,满足排涝方案要求;各闸门过流流量与其河道底宽成正比,各闸门各过程线波动程度与其河道底宽成反比;水网先蓄后排削峰57.21 m^(3)/s,错峰2.83 h,调蓄洪量169万m^(3),削峰率42.45%,防洪排涝效益显著。该方法具备一定的模拟效果及精度,可为相关人工建设水网的防洪排涝研究提供借鉴和指导。

基于HEC-RAS的竹根池水库溃坝洪水风险研究

为避免发生水库漫坝水淹周边电站厂房,采用HEC-RAS对向家坝电站周边的竹根池水库进行二维溃坝洪水模拟计算,分析其演进过程及最大的影响范围。结果表明,溃口洪峰大小取决于溃口底宽、溃决水头及溃决时间;竹根池溃坝对向家坝下游的机电设备仓库及金沙江大桥基本无影响,对几条进厂公路和上坝公路产生轻微影响。该分析结果可为竹根池水库及向家坝电厂的安全运行及防洪应急管理提供科学依据。

基于HEC-RAS的千河流域宝鸡段溃坝洪水风险评估

水库是大量蓄水的水利工程,对生产生活提供便利,但同时溃坝洪水一般具有极高伤害性,进行洪水溃坝风险评估对保障下游居民安全有重要意义.以千河流域宝鸡段的冯家山水库为例,利用HEC-RAS模型,模拟了溃坝洪水淹没进程,并对淹没范围和流速分布进行分析.洪水演进数据结合灾害系统理论构建风险评估模型,从危险性、易损性角度,通过GIS方法实现风险评估并分为五个等级.结果表明:①100年一遇洪水淹没总面积为274.581km^(2),危险水深占全部水深93%,河道最高流速可达到14.34m/s.②洪水危险性自西向东逐渐降低,整体危险性中度偏下.③易损性在河道附近两侧较低,距离河道较远的部分易损性提高,整体是处于中低水平.④溃坝洪水风险水平中等,对淹没区各乡镇风险划分,危险区明显集中,主要在贾村镇、长青镇、千河镇以及揉谷镇.研究成果对千河流域宝鸡段下游洪水避难预警系统建设和人口转移有一定参考意义.

基于HEC-RAS的跃进水库溃坝洪水风险分析

水库大坝一旦发生溃坝,溃坝洪水会对下游造成毁灭性的影响。该文以黑龙江省五大连池市跃进水库为研究对象,使用HEC-RAS软件建立二维非恒定流溃坝模型,模拟跃进水库溃坝后的洪水淹没范围和时间演变特征。研究结果可为水库防洪抢险指挥和应急预案的编制提供理论依据。

基于HEC-RAS的山洪危险性评价

基于HEC-RAS模型,选取重现期为5年一遇、20年一遇和50年一遇的降雨工况进行水动力特征模拟,结果表明:鹿坝沟平均水深、最大水深、平均流速、最大流速和淹没面积随重现期的增加而增大;同时利用Arcgis叠加分析洪水的流速与水深进行危险性分析研究。结果表明:鹿坝沟危险性总面积随重现期的增加而增大,并基于HEC-RAS的洪水淹没模拟分析具有较高的精确性,研究成果可为该流域内受到洪水灾害影响人员疏散方案的制定提供一定参考。

HEC-RAS模型在河道治理工程水面线推求中的应用

为掌握山区复杂流态河流暴雨洪水特性,以吴上湾河大埠口村段河道治理工程为例,利用HEC-RAS软件构建迭代推演水面线分析模型,并结合流域特征值及设计洪水成果,模拟获得控制断面治理前后10年一遇洪水条件下的河道水面线数据。分析结果表明:治理前河道滩地上沙场侵占行洪断面,导致河道水位壅高。通过主河槽扩挖补偿和混凝土挡土墙护岸等措施治理后,河道流速降低、行洪能力增加。HEC-RAS软件对于天然河道复杂流态水文水力计算具有较强适用性,推求数据合理可信。

HEC-RAS在贵州山区中小河流治理工程方案优化中的应用

HEC-RAS具备简洁的操作界面,简单的模型设置方式,处理复杂河流及涉河建筑物的强大能力以及准确的模拟计算结果,在河道治理工程分析计算中应用广泛。以贵州省小黄泥河树嘎村段河道治理工程为例,利用HEC-RAS模型对研究区建立一维恒定流模型,进行多方案的分析计算,可为优化工程治理方案布置提供决策参考。计算结果表明,HEC-RAS模型模拟计算简便,水面线成果精度较高,可为中小河流治理方案设计和优化提供决策参考,满足贵州山区中小河流治理工程的精度要求。

HEC-RAS软件在城市河道水面线计算中的应用

以商城县城市河道为例,采用HEC-RAS软件,模拟分析了在不同设计频率洪水下的水面线,为城市河道治理工程提供水面线计算依据。计算过程表明,HEC-RAS软件在分析计算城市河道水面线时有较好的适用性。

ICE JAMS IN A SMALL RIVER AND THE HEC-RAS MODELING

This paper describes a model of a 3.06km long river reach between two small reservoirs under both open flow and ice covering conditions for different operational settings of the stoplogs in the downstream reservoir. The HEC-RAS model developed by the Hydrological Engineering Center of US Army Corps of Engineers was used to compare different approaches in terms of flow velocity, water level and the Froude number. The impacts of heavily vegetated main channel and floodplain on ice accumulations were investigated. And it is shown that this vegetation plays a significant role in the formation of river ice jam during winter period and thus the vegetated channel has strong influence on ice flooding. In addition, the paper explores the impact bouh of the operation of the stoplogs during the winter period and the presence of the downstream dam on the accumulation of ice jam along this river reach.

基于HEC-RAS的水库下游水动力模型构建及三维可视化应用

以皎口水库为例,利用HEC-RAS软件建立水库下游一二维耦合水动力模型,通过“烟花”“梅花”2场台风的历史洪水模拟计算钟家潭、章水断面的水位变化过程,与实际情况对比发现,该模型计算结果合理准确;模拟极端洪水(P=1%、P=0.1%)情况下,水库下游淹没范围、淹没水深、淹没历时等要素;基于BIM(Building Information Modeling)、GIS(Geographic Information System)等技术进行洪水演进过程三维立体可视化展示,为水库下游洪水风险分析提供技术支撑,为智慧水利建设提供解决方案。

采用STAMP-24Model的多组织事故分析

安全生产事故往往由多组织交互、多因素耦合造成,事故原因涉及多个组织。为预防和遏制多组织生产安全事故的发生,基于系统理论事故建模与过程模型(Systems-Theory Accident Modeling and Process,STAMP)、24Model,构建一种用于多组织事故分析的方法,并以青岛石油爆炸事故为例进行事故原因分析。结果显示:STAMP-24Model可以分组织,分层次且有效、全面、详细地分析涉及多个组织的事故原因,探究多组织之间的交互关系;对事故进行动态演化分析,可得到各组织不安全动作耦合关系与形成的事故失效链及管控失效路径,进而为预防多组织事故提供思路和参考。

基于改进24Model-ISM-SNA建筑工人不安全行为关联路径研究

建筑施工现场环境复杂,为有效控制不安全行为发生,基于行为安全“2-4”模型对360份具有代表性的建筑安全事故调查报告进行分析,提取出22个不安全行为的主要影响因素。利用灰色关联分析方法(GRA)改进的集成ISM-SNA模型,将不安全行为风险因素划分为表层、过渡层与深层,然后对风险因素进行可视化分析、中心度分析及凝聚子群分析,揭示了各致因因素间的关联关系和传导路径。结果表明,建筑工人不安全行为影响因素可划分成7级3阶的多级递阶结构,安全意识、现场监管、外部环境是建筑工人不安全行为的关键影响因素,同时现场监管和隐患排查到位能有效降低不安全行为的发生。