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We are pleased to send you the first FLO-2D Software newsletter. We anticipate publishing a newletter at the end of each quarter to announce new tools and features available for downloading, release dates for new model versions, and partnering. Each issue will highlight a new tool or sofware. In this edition, we present our new 2-D triangular mesh river model RiverFLO-2D.


FLO-2D Version 2009.06 Release Notes:



Working with Large Project Data Files

The Grid Developer System (GDS) has a new procedure to facilitate the creation of large projects involving multiple LiDAR DTM point files and FLO-2D grid systems in excess of 1 million grid elements. Some of these enhancements have been developed for California Department of Water Resources Central Valley Flood Evaluation and Delineation Program.

The original GDS interpolation method was limited to about 15 million DTM points. To circumvent this limitation and allow the processing of virtually unlimited number of elevation point data, the new method uses state-of-the-art computational algorithms that do not require importing the points and significantly extends the DTM interpolation capability.

Create Levees from 3-D Polylines

A new GDS levee tool can automatically create levees from 3-D polylines contained in files. The procedure will assign levee crest elevations based on the polyline vertex elevations and will ensure that the levee has no gaps. Creating a 120 mile levee now takes less than 20 seconds greatly facilitating levee modeling.

The user can also generate a levee from an interactive polyline. The polylines are created with mouse clicks. For each mouse click, the GDS generates the levee data where the polyline intersects grid elements. There are 3 options for assigning the levee crest elevations:

  • Uniform option assigns a unique value to all levee elevations
  • Interpolate assigns elevations between 2 values
  • DTM assigns a crest elevation from the average 5 highest DTM points in each grid element

Automatically Generate Building Storage Loss Data Files

Many flood districts and cities are creating building shape files. Building storage loss and obstructions using the area and width reduction factors (ARF and WRF factors) can now be automatically assigned from user provided building polygon shape files. The GDS will generate the ARF and WRF values for each grid element based on intersection of shape file polygons with the FLO-2D grid system.


GDS in the Process of Assigning the ARF values to Building Polygons


Spatially Variable Limiting Froude Numbers

The user can now assign limiting Froude numbers to individual floodplain elements. Previously the limiting Froude number was a global value for all floodplain elements. The user can specify spatially variable limiting Froude numbers for n-value adjustment with shape files, polygons and by individual element assignment.

User Assigned Courant Number

The Courant number was hardwired (C = 1.0) in previous versions of the FLO-2D model as one of the numerical stability parameters. By allowing the user to assign the Courant number (in the TOLER.DAT file), it has been found that the model can run faster and still maintain stability even if the DEPTOL and WAVEMAX values are assigned to 0. A Courant number in the range from 0.3 to 0.8 can eliminate most numerical surging.

Automatically Generate Binary Backup Output Files

In previous releases a binary backup file was written at the end of the simulation time allowing hot starts upon model execution. In the new update, the user may select an option to generate a binary hot start file at the end of each output interval. This enables the user to restart and recover the simulation for the last successfully written output interval in the event of model interruption or terminations such as a power outage.

 

Integration with USGS MODFLOW

FLO-2D has a number of new features. The primary new component is the USGS groundwater model MODFLOW that has been linked with the FLO-2D model for surface-groundwater flow simulations. The two models can exchange surface flow to groundwater or vice versa. The model simulation is controlled by the FLO-2D model timesteps which are typically smaller than the MODFLOW model.



Run time optimization

The FLO-2D model is being optimized to take advantage of parallel computation in multiple processor computers. This is an on-going task. Runtime speeds have increased from 1.5 to 2.5 times. We anticipate significant reductions in simulation times over the next year as more OpenMP code is embedded in the model.


Levee breach simulations

The Corps of Engineers fragility curves for levee and dam breach methodology was added to the FLO-2D beach component in Version 2009. This will enable the prediction of levee failure locations. The application of fragility curves integrates geotechnical risk with the computation of flood hydraulics. This tool will enhance the prediction of levee breach floodplain storage with downstream flood attenuation.


Importing HEC-RAS projects

Existing HEC-RAS data files can now be imported to the GDS and used to locate channels and create the FLO-2D cross section and channel data files. HEC-RAS cross sections can be interactively assigned to channel elements, allowing its integration with the 2-D floodplain 2-D grid.


Other new tools


The GDS and Mapper have a number of new tools, features and displays including watershed delineation, 3-D ground surface plots, and new channel cross section analysis.


New frequency analysis software
FreqPlot is our new rainfall and flood peak discharge frequency analysis program that significantly improves evaluations in a quick and convenient manner. Four frequency plotting distributions including extreme value, log extreme value, normal, and log normal (Log Pearson III) can be reviewed simultaneously to determine which frequency distribution provides the best fit to the data.


New RiverFLO-2D Model


RiverFLO-2D is a two-dimensional hydrodynamics model for river and floodplain routing. This software was released in January 2009. It is a finite element model that complements the FLO-2D model by computing flow hydraulics and sediment transport with rigid or mobile bed. Flexible triangular meshes can be generated and refined around key river features, generating detailed velocity fields for rivers, overbank flooding, and dam break simulations. The model can simulate both steady and unsteady flows with wetting and drying allowing initial dry river bed without spin-down or other cumbersome procedures.

Big Hole Diversion DamBig Hole River Diversion Dam Overhaul


The Big Hole River Diversion Dam, located near Divide, Montana is a municipal water intake structure, owned and managed by the City and County of Butte-Silver Bow (BSB), Montana, and serves as Butte’s main source of potable water. The existing concrete diversion dam and associated intake structure is approximately 80 years old and is in poor condition. The structure is a also barrier to fish passage and a safety hazard for public recreation.

BSB tasked DOWL KHM of Butte, MT with the design of a replacement structure. The purpose of the project is to provide reliable water, accommodate fish passage, and improve structure safety. Due to the design complexities, conventional one-dimensional models were considered inappropriate for evaluating the hydraulic performance.

RiverFLO-2D was selected to simulate highly detailed 2-D hydrodynamics around the complex structure. The model was successfully calibrated to flow conditions at the existing dam and was then used to complete the design consisting of a trapezoidal rock weir spillway and a series of plunge pools. Modeling results are being reviewed by state and federal permitting agencies.


1. Finite Element Mesh on the Intake
Velocity Field on the Intake
2. Velocity Field on the Intake

For additional information regarding this project contact:
Dick Talley, PE at DOWL HKM, Butte, MT (406) 723-8213.
For more information about RiverFLO-2D please go to:
http://www.flo-2d.com/products/riverflo-2d/

 


Swimming Downstream (and looking ahead)




We anticipate significant changes to the FLO-2D model landscape for the next version in 2011 including a storm drain model, geo-referencing components and variable size grid system. We are currently working on runtime linkage to XP Software’s storm drain model. This new component will enable FLO-2D urban surface flooding simulations to interact with pressure storm drain flows on a computational timestep basis. Flow will be exchanged between the two models with floodwaters entering the storm drains and storm drain flow returning to the surface model. With the existing street flow component and the component for the loss of storage and flow obstruction due to buildings, the storm drain component will complete the FLO-2D urban model.

In the next release, the FLO-2D GDS processor program will have geo-referenced components (such as channels, streets, levees, infiltration, etc.) that will be independent of the grid system. This will enable the grid systems to be revised or completely recreated without re-assigning the components to a new grid system. The user will be able to convert a FLO-2D model with a 300 ft grid system to a 100 ft grid system seamlessly.

In conjunction with the geo-referenced components, we will introduce variable size grid systems which will permit smaller grid elements within a large grid system. Where higher resolution near the project site is required, the user will be able to reduce the grid system as a multiple of 2, 4 or 16 in order to refine the flow dynamics without significantly impacting the entire simulation.

 

Outreach

California: In 2007 FLO-2D was selected by the California Department of Water Resources to simulate the floodplain hazard for the Central Valley Floodplain Evaluation and Delineation Program. When completed, this program will result in the largest ever state-funded levee evaluation and floodplain delineation program in the Nation. The program will enter the flood simulation phase in the coming months.

Arizona: FLO-2D Software, Inc. recently signed a contract with the Flood Control District of Maricopa County encompassing the City of Phoenix, Arizona to provide engineering services and training related to hydraulics, sediment transport, and other advanced river issues based on the FLO-2D model over a 2-year period. This represents an opportunity to develop new FLO-2D tools for flood routing with the District.

Hungary: The Water and Environmental Damage Control Department of the Ministry of Environment and Water is evaluating the FLO-2D model for application on the Tisza and Danube Rivers for the design of flood mitigation detention basins. If successful, the Department may initiate training and application of the model to other water districts in the country.

 

 

 

FLO-2D Version 2009
New Components and Features


Some of the new components and features for the 2009 Version release include:


1. MODFLOW Surface/Groundwater Integration.

Model groundwater flow and surface water interaction with MODFLOW at runtime with the FLO-2D model. Complete integrated model that will exchange groundwater and surface water on a timestep basis.


2. Optimized for 64-bit Multiple Processors.

Depending on the project size and complexity, computer runtime speeds for the FLO-2D will be increase in the range from 1.5 to 2.5 times. This represents a significant decrease in computer runtime.


3. RiverFLO-2D In-channel 2-D Hydrodynamics Model.

RiverFLO-2D is a two-dimensional, finite element model for river channels and floodplain. It is designed to complement the FLO-2D model by providing detailed hydrodynamic predictions of 2-D flows inside a rigid or mobile bed channel. Overbank flooding, dam break simulations and detail velocity fields can be simulated with RiverFLO-2D.


4. FreqPlot Program. A new rainfall and flood peak discharge frequency program will compare four frequency plotting distributions including extreme value, log extreme value, normal, and log normal (Log Pearson III). Each distribution curve can be plotted to determine which frequency distribution provides the best fit to the data. The various return period peak discharges or rainfall is presented for all the distributions in a single table.


5. Dam and Levee Breach Fragility Curves.

The Corps of Engineers fragility curves for levee and damage breach will improve locating potential breach failures. The application of fragility curves melts geotechnical risk with flood hydraulics to locate breach initiation. This tool will enhance the prediction of levee breach floodplain storage with downstream flood attenuation.


6. Enhanced HEC-RAS Data File Integration.

Existing HEC-RAS data files can now be imported to the GDS and used to locate channel and create the FLO-2D cross section and channel data files.


7. Many New GDS and Mapper Features.

The GDS and Mapper will have a number of new tools, features and displays including watershed delineation, 3-D ground surface plots, and new
channel cross section analyses.


8. Sediment Routing Enhancements.

Two equations for computing sediment transport capacity have been added Karim-Kennedy and MPM-Smart being the total selection to 9 eqations.