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FLO-2D | 二维洪水与土石流数值模拟套装软件

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FLO-2D模式在1986年被概念化预测泥石流液压系统。美国联邦紧急事务管理局(FEMA)支持初始的模型开发并于1988年应用于科罗拉多州的特柳赖德,在过去的30年中,FLO-2D已成为广泛使用的商用洪水模型。FLO-2D优点在于它能够以高分辨率和无限细节模拟城市洪水,包括雨水排放系统。使用小至10英尺(3米)的元素,FLO-2D在体积守恒,速度,数值稳定性和细节方面是一个优秀的模型。FLO-2D设置简单,编辑更简单(无网格再生)。


FLO-2D是一种模拟河流,冲积扇,城市和沿海洪水的洪水路径模型。

FLO-2D可以解决任何不同的洪水问题,包括:

  • 河岸边洪水泛滥

  • 流域降雨和径流

  • 城市洪水与街道流动,流动阻碍和储存损失

  • 海啸和飓风风暴潮的陆上进展

  • 风暴排水模型

  • 泥浆和泥石流

  • 无约束的冲积扇流动

  • 地表水和地下水相互作用

  • 大坝和大堤突破

  • 尾矿坝失效和容积雨岑

  • 洪水保险研究

FLO-2D是一个综合的水文和水力模型,因此䢕分离降雨/径流和洪水路线。


FLO-2D分为FLO-2D Basic和FLO-2D Pro两个版本。其中FLO-2D Pro是市场上全面且实惠的2D洪水路由工具。请参阅下面的组件列表,为:

  • 全风暴排水/地表水界面

  • 渠道风暴排水交换

  • 沙井爆裂

  • 降雨/渗透与空间变化的NEXRAD数据

  • 墙和建筑物流动阻碍

  • 建筑屋顶径流,落水管控制,护墙

  • 墙和堤坝破裂和坍塌

  • 建筑倒塌

还有很多......


洪水建模组件



FLO-2D Pro主要特点:


解决方案算法

该模型使用完整的动态波动量方程式和具有八个潜在流向的中央有限差分路由方案来预测方形网格单元系统上的洪水波进程。


创建网格系统 

FLO-2D需要两组数据:地形和水文学。地形可以由数字地形模型(DTM)点,等高线图或测量数据表示。网格元素高程是通过DTM点的插值分配的。一个称为Grid Developer System ( GDS ) 的处理程序会生成网格系统并分配高程。典型的网格元素大小范围为10英尺(3M)至500英尺(150m)。方格元素的数量是无限的。


背景图像

可以将航空图像作为背景导入到GDS中,一辅助图形编辑。GDS需要一个Word文件才能读取图像。


体积节省,路由算法稳定性和时间步长

准确的洪水调度的关键是节水。FLO-2D跟踪并报告体积守恒。数值稳定性与体积守恒相关,当模型守恒体积时,模型运行速度更快。计算时间步长根据洪泛区,河道和街道流量的数值稳定性标准来增加或减少。


流入水文图或降雨

流入水文图可以分配给巷道或洪泛区节点。流入节点的数量是无限的。任何ASCII数据格式的水线图都可以用作输入。FLO-2D还可以允许降水模型,并且在被淹表面上可能会下雨。


使用NEXRAD数据复制历史降雨事件

可以使用NESRAD降雨数据置信模型校准。可以使用GDS将NEXRAD ASCII栅格降雨数据插值到栅格元素。生成文件RAINCELL.DAT,以便每个网格元素在NEXRAD记录的间隔(通常为5或15分钟)中区分降雨数据。然后可以使用时空变化的降雨来模拟历史降雨事件。调整NEXRAD数据以适应雨量计是汇编降雨数据所必需的。


渗透和蒸发损失

可以使用Green-Ampt,SCS曲线编号或HOrton方法来计算渠道或洪泛区的空间渗透率。Green-Ampt和SCS相结合的方法将使曲线数据降雨损失能够与传输损失一起建模。洪泛区和河道流量均可计算地表水蒸发量。


渠道流量及渠道和洪泛区流量的交换

用矩形,梯形或测量航界面模拟一维通道刘。在八个方向(4个罗盘方向和4个对角方向)上模拟了无限制洪泛区流量。针对每个时间步长模拟通道的溢流或回流。对于详细的模拟,通道可以大于网格元素。支流流入是无限。GDS可以将HECRAS横截面转换为FLO-2D格式的数据文件。


街流

将街道模拟为带有路缘的潜矩形通道。街道可以与洪泛区相交并交换流量。


水工结构

水力结构可以代表桥梁,涵洞,堰或其他水力控制特征。通过用户指定的排量额定曲线或分配给通道或洪泛区元素的表格模拟水工结构。逆流是可能的。不连续的网格元素之间可能会发生涵洞流动。广义涵洞方程将说明入口和出口的控制。


雨水排放系统

有一个完全集成的地表水和雨水排放系统。雨水排放组件可以包括无线的管道系统,入口,排水口和入孔盖。使用物种雨水排放入口类型模拟入口控制。人孔盖可以弹出。通过入口或带有燃控的接线盒的流出是基于管道压力和地表水高程之间的比较。有多种类型的排污口,其中可能包括水下排污口和挡板。


堤坝和堤坝溃坝失败

可以通过在网格元素边界上指定波峰高程来模拟堤坝,路堤和大坝。有几种地方破坏方案,包括全面的充蚀侵蚀模型,可以选择就中沉积物输送方程式。堤坝破坏可以通过脆弱性曲线启动。


建筑物和流动障碍

可以对由于建筑物或要素造成的洪泛区存储损失进行建模。可以从潜在的淹没中移除一部分或整个元素。网格元素流交换在所有八个流向中都可能部分或全部受阻。


屋顶径流

屋顶的雨水径流可以通过落水口进水控制和护墙来模拟。可以分配可变的深度公差值(TOL)以荣南其他屋顶存储。屋顶的降雨径流将根据屋顶的坡度添加到建筑物周围的地下水表面。屋顶顶盖可以将水流添加到地表水中,而洪水仍将围绕建筑物。


低影响发展

可以使空间可变的公差深度(TOL)值来模拟用于站点开发的批量洪水蓄水库。这可能包括生物保留,绿色屋顶,御水花园,可渗透的人行道,排水系统断开,沼泽和现场存储。分配TOL值以表示给定网格元素上的复合低影响开发(LID)技术。不同的网格元素课代表不同的LID技术。


分配通道流

可以用小溪和沟渠代替表层流模拟陆上流。较小的分配通道会随着更多的流量进入沟渠而扩大。这种分配流可以缩短冲积扇洪水泛滥的时间。


泥浆和泥石流

FLO-2D模型使用二次流变模型模拟泥流,该模型包括粘性应力,屈服应力,湍流和分散应力项,他们是沉积物浓度的函数。粘性泥浆流可能会停止流动,繁殖,泥浆流可能会因流入而被稀释。


泥沙输送

使用11个可用方程式之一来计算河道和陆地流量的泥沙输送。沉积物的体积以网格元素为基础。冲刷和沉积在通道横截面上不均匀分布。可以通过尺寸分数和装甲模拟沉积物路径。


地下水与地表水交换

FLO-2D模型在运行时域USGS地下水MODFLOW模型关联。地下水好地表交换可以双向发生。


限制费罗伊德数

可以将限制弗洛德编号分配给渠道,街道和洪泛区网格元素。当特定网格元素中的极限弗洛德数超过是,模型将增加粗糙度值以抑制数值波动。对于模型泛洪路由,为合理的Froude数校准n值非常有效。


模型输出 ,结果和映射

文本输出被写入ASCII文件。后处理器MAPPER程序创建阴影轮廓,线轮廓或网格元素流深图和危险图。可以评估洪水损失,并且可以将FLO-2D输出视为洪水动画。MAPPER还将自动生成可以直接导入到ArcGIS的形状文件。DFRIM工具可用于FEMA FIS研究。

现在可以使用HDF5或NetCDF二进制格式将结果写入TIMDEP输出文件。FOL-2D PRO根据ITIMTEP变量上指定的值以不同的格式写入TIMDEP输出文件:

对于选项0,1,2,3,4,必须指定输出时间步TIMTEP。TIMDEP文件中打印的输出变量的数量也得到了扩展。



FLO-2D主要特点:

求解算法

该模型使用完整的动态波动量方程式和具有八个潜在流向的中央有限差分路由方案来预测方形网格单元系统上的泛洪波进程。


创建网格系统

FLO-2D需要两组数据:地形和水文学。地形可以由数字地形模型(DTM)点,等高线图或测量数据表示。网格元素高程是通过DTM点的插值分配的。名为Grid Developer System(GDS)的处理器程序将生成网格系统并分配高程。典型的网格元素大小范围为10英尺(3m)至500英尺(150m)。方格元素的数量是无限的。


背景

图像可以将航空图作为背景导入到GDS中,以辅助图形编辑。


节约

流量,路由算法的稳定性和时间步长准确的洪水路由的关键是节约流量。FLO-2D跟踪并报告体积守恒。数值稳定性与体积守恒相关,当模型守恒体积时,模型运行速度更快。计算时间步长数据值稳定性标准题赠或递减。


流入水文图或降雨

流入水文图可以分配给河道节点或洪泛区节点。流入节点的数量是无限的。任何ASCII数据格式的水线图都可以用作输入。FLO-2D还可以充当降雨径流模型,并且在被淹表面上可能会下雨。


河道和洪泛区流量的交换

用矩形,梯形或测量横截面模拟一维河道流量。在八个方向(4个罗盘方向和4个对角线方向)上模拟了无限制洪泛区流量。针对每个时间步长模拟通道的溢流或回流。对于详细的模拟,通道可以大于网络元素。直流流入是无限的。GDS可以将HECRAS横截面转换为FLO-2D格式的数据文件。


街道流量

街道被模拟为带有路缘的浅矩形通道。街道可以与洪泛区相交并交换流量。


水工结构

水工结构可以代表桥梁,涵洞,堰或其他水力控制特征。通过用户指定的排量额定曲线或分配给通道或洪泛区元素的表格模拟水工结构。不连续的网格元素之间可能会发生涵洞流动。


建筑物和水流障碍物

可以模拟由于建筑物或要素造成的洪泛区存储损失。可以从潜在的淹没中移除一部分或整个元素。网格元素流交换所有八个流向中都可能部分或全部受阻。


支流河道流量可以用小溪和沟壑而不是表层留来模拟陆上流量。较小的分配通道会随着更多的流量进入沟渠而扩大。这种分配流改善了集中在冲击扇上的时间。


限制弗劳德编号

可以将限制弗劳德编号分配给通道,街道和洪泛区网格元素。当特定网格元素中的极限弗洛德数超过时,模型将增加粗糙度值以抑制数值波动。对于模型泛洪路由,为合理的Froude数校准n值非常有效。


模型输出,结果和映射

文本输出被写入ASCII文件,后处理器MAPPER程序创建阴影轮廓,线轮廓或网格元素流深图和危险图。可以评估洪水损失,并且可以将FLO-2D输出是为洪水动画。Mapper还将自动生成可以直接导入到ArcGIS的形状文件。


【英文介绍】

Key Features

  • Solution Algorithm

The model uses the full dynamic wave momentum equation and a central finite difference routing scheme with eight potential flow directions to predict the progression of a floodwave over a system of square grid elements.


  • Creating a Grid System

FLO-2D requires two sets of data: topography and hydrology. -Topography can be represented by a digital terrain model (DTM) points, contour mapping or survey data. The grid element elevations are assigned from an interpolation of the DTM points. A pre-processor program called the Grid Developer System (GDS) generates the grid system and assigns the elevations. A typical grid element size will range from 10 ft (3 m) to 500 ft (150 m). The number of square grid elements is unlimited.


  • Backgound Images

Aerial images can be imported to the GDS as background to assist graphical editing. The GDS requires a world file to read images.


  • Volume Conservation, Routing Algorithm Stability and Timesteps

The key to accurate flood routing is volume conservation. FLO-2D tracks and reports on volume conservation. Numerical stability is linked to volume conservation and when the model conserves volume the model runs faster. Computational timesteps are incremented or decremented according to numerical stability criteria for floodplain, channel and street flow.


  • Inflow Hydrographs or Rainfall

Inflow hydrographs can be assigned to either the channel or floodplain nodes. The number of inflow nodes are unlimited. Any ASCII data format hydrograph can be used as input. FLO-2D can also perform as a rainfall runoff model and rain can occur on the flooded surfaces.


  • Replicate Historical Rainfall Events with NEXRAD data

Model calibration can be performed with NEXRAD rainfall data. NEXRAD ASCII grid rainfall data can be interpolated to the grid elements using the GDS. A file RAINCELL.DAT is generated so that each grid element distinct rainfall data in the NEXRAD recorded intervals (typically 5 or 15 minutes). A historical rainfall event can then be simulated with spatially and temporally varied rainfall. Adjusted NEXRAD data to rain gages is necessary to compile rainfall data.


  • Infiltration and Evaporation Losses

Spatially variable infiltration for the channel or floodplain can be computed with either Green-Ampt, SCS curve number or Horton methods. Combined Green-Ampt and SCS methods will enable curve number rainfall losses to be model with transmission losses. Surface water evaporation can computed for both floodplain and channel flow.


  • Channel Flow and Exchange of Channel and Floodplain Discharge

One-dimensional channel flow is simulated with rectangular, trapezoidal or surveyed cross sections. Unconfined floodplain flow is simulated in eight directions (4 compass directions and 4 diagonal directions). Overbank flow or return flow to the channel is simulated for each timestep. For detailed simulations the channel can be larger than the grid element. Tributary inflow is unlimited. The GDS can convert HECRAS cross sections into a data file formatted for FLO-2D.


  • Street Flow

Streets are simulated as shallow rectangular channels with a curb. Streets can intersect and exchange flow with the floodplain.


  • Hydraulic Structures

Hydraulic structures can represent bridges, culverts, weirs or other hydraulic control features. Hydraulic structures are simulated by user specified discharge rating curves or tables assigned to either channel or floodplain elements. Reverse flow is possible. Culvert flow can occur between grid elements that are not contiguous. The generalized culvert equations will account for inlet and outlet control.


  • Storm Drain System

There is a fully integrated surface water and storm drain system. The storm drain components can include an unlimited pipe system, inlet, outfalls and manhole covers. Inlet control is simulated with five storm drain inlet types. Manhole covers can be popped. Outflow through the inlets or junction boxes with manholes is based on the comparison between pipe pressure and surface water elevation. There are numerous types of outfalls which may include underwater outfalls and flapgates.


  • Levees and Levee and Dam Breach Failure

Levees, road embankments and dams can be simulated by specifying crest elevations on a grid element boundary. There a several levee failure options including a comprehensive breach erosion model with a choice of nine sediment transport equations. Levee breaches can be initiated with fragility curves.


  • Buildings and Flow Obstructions

Floodplain storage loss due to buildings or features can be modeled. A portion or the entire element can be removed from potential inundation. Grid element flow exchange can be partially or entirely obstructed in all of the eight flow directions.


  • Roof Runoff

Rainfall runoff from roofs can be simulated with downspout inlet control and parapet wall storage. Variable depth tolerance values (TOL) can be assigned to accommodate other roof storage. The rainfall runoff from the roof will be added to the ground water surface around the building based on the roof slope. A positive roof head enables the flow to be added to the ground surface water while the flooding will still go around the building.


  • Low Impact Development

Lot-size flood retention storage for site development can be simulated with a spatially variable tolerance depth (TOL) value. This may include bio-retention, green roofs, rain gardens, permeable pavement, drainage disconnection, swales, and on-site storage. TOL values are assigned to represent composite Low Impact Development (LID) techniques on a given grid element. Different grid elements may represent different LID techniques.


  • Distributary Channel Flow

Overland flow can be simulated in small rills and gullies instead of sheet flow. The small distributary channels expand as more flow enters the gully. This distributary flow improves the time of concentration for floods progressing over alluvial fans.


  • Mud and Debris Flows

Mudflow is simulated by the FLO-2D model using a quadratic rheological model that includes viscous stress, yield stress, turbulence and dispersive stress terms as a function of sediment concentration. Viscous mudflows may cease flowing and conversely, mudflows can be diluted by inflow.


  • Sediment Transport

Sediment transport is computed for both channel and overland flow using one of eleven available equations. Sediment volume is conserved on a grid element basis. Scour and deposition are non-uniformly distributed on channel cross sections. Sediment routing by size fraction and armoring can be simulated.


  • Groundwater and surface water exchange

The FLO-2D model is linked with the USGS groundwater MODFLOW model at runtime. Groundwater and surface exchange can occur in both directions.


  • Limiting Froude Numbers

Limiting Froude numbers can be assigned to the channels, streets and floodplain grid elements. When the limiting Froude number is exceeded in a particular grid element, the model will increase the roughness value to suppress numerical surging. It is efficient for the model flood routing to calibrate n-values for reasonable Froude numbers.


  • Model Output, Results and Mapping

Text output is written to ASCII files. The Post-processor MAPPER programs create shaded contours, line contours or grid element flow depth plots and hazard maps. Flood damages can be assessed and the FLO-2D output can be viewed as a flood animation. MAPPER will also automatically generate shape files that can be imported directly to ArcGIS. A DFRIM tool is available for FEMA FIS studies.

Results can be written now to the TIMDEP output file using a HDF5 or NetCDF binary format. FLO-2D PRO writes the TIMDEP output file in different formats according to the value specified on the ITIMTEP variable:


0: NO TIMDEP.OUT RESULTS

1: ONLY TIMDEP.OUT IS WRITTEN

2: TIMDEP.OUT and HDF5 ARE WRITTEN

3: TIMDEP.OUT and NETCDF4 FILES ARE WRITTEN

4: ALL OUTPUT FILES ARE WRITTEN


For options 0, 1, 2, 3 or 4 the output timestep TIMTEP must be specified. The number of output variables printed in the TIMDEP files was also expanded.



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