DAMBRK Software, Focused on Oconee -resurrected 1992 FERC EAP model. (b)(7)(F), The Jocassee breach parameters accepted by FERC for 1992 EAP work., Domino-effect assumes Keowee Dam failure.Jocassee and Keowee water levels varied for resultant sensitivity. Using nowe lake levels, 'Sunny Day' Jocassee Dam Failure resulted in.

1. Dambrk software, free download Average ratng: 9,7/10 7762votes. The FLDWAV program, developed by the National Weather Service (NWS), is a generalized flood routing program with the capability to model flows through a single stream or a system of interconnected waterways. FLDWAV, Version 1.0.0, released in November 1998, replaced the NWS.
2. The maximum velocity of 1.72 m/s occurred at a distance of 11.2 km and a minimum velocity of 0.06 m/s at a distance of 14 km downstream of the dam section. Conclusions The dam break analysis of Thenmala Dam is carried out using BOSS DAMBRK software. The maximum precipitation is found out to be 396mm and the corresponding flood to be 4589.42m.
3. Computer simulations for one of the worse-case scenarios on dam failure using BOSS DAMBRK software accounted for dam failure, storage effects, floodplains, over bank flow and flood wave attenuation. The simulated results reviewed a maximum flow velocity of 2.40 m/s with a discharge of approximately 242 m³/s occurred at 1.00 km downstream.
4. BOSS DAMBRK software accounted for dam failure, storage effects, floodplains, over bank flow and flood wave attenuation. The simulated results reviewed a maximum flow velocity of 2.40 m/s with a discharge of approximately 242 m³/s occurred at 1.00 km downstream. The maximum discharge increased from 244 m3/s (flow velocity = 1.74 m/s occurred.

Adam Morstad explains how the RiverCAD software package from Boss International automates many of the processes in river and dam failure analysis that can be tedious and error-prone when done by hand

THE SWISS ARMY KNIFE must have seemed ingenious to its first users. Imagine the thrill of replacing what used to be a disorganised satchel of single-purpose tools with one multi-purpose contraption. The kind of convenience, reliability, and practicality that Karl Elsener designed into his new jackknife in 1891 was far ahead of its time, evidenced by the tool’s remaining popularity.

Fast-forward roughly one century. Though the world has mechanised and complex tools like the Swiss Army Knife have become commonplace, the need for that kind of convenience has not faded. In fact, for professional hydraulic engineers it has only grown.

By 1990, drafters, architects, and engineers alike were doing most of their technical drawing with computers. Programs like AutoCAD, DAMBRK, and HEC-2 were running on personal computers all over the country while many new modelling software components continued to arrive on the market. Technology was increasing productivity, but many different programs would often still be necessary to accomplish a single task. To cut through this confusion, Boss International sought to develop a Swiss Army Knife of its own for the river modelling industry in the form of RiverCAD, a modular, scalable software package for modelling and analysing river systems and water surface profiles.

Built with a CAD engine that supports HEC-RAS, HEC-2, UNET, and DAMBRK, RiverCAD has been developed to automate many of the mundane tasks that have made hydraulic engineering analysis so time consuming. RiverCAD can compute water surface profiles for modelling dams, bridges, culverts, spillways, levees, bridge scour, flood inundation, floodway delineation, floodplain reclamation, stream diversions, channel improvements, and split flows.

RiverCAD is integrated with its own 3D CAD system that is compatible with AutoCAD and MicroStation. The software’s graphical capabilities are extremely advanced, allowing multiple CAD drawings (.DWG files) to be opened simultaneously with each drawing having four separate viewports displayed. RiverCAD’s cross-section and profile plots can be output at any drawing scale, and a sophisticated 3D surface renderer allows users to quickly create professional 3D shaded plots of the river reach being studied.

Recently, RiverCAD was used to formulate emergency action plans, dam failure modelling studies, and inundation mapping for the Catskill and Delaware Watershed System in the US. The watershed contains six dams and respective reservoirs that provide 90% of the daily water for New York City. The engineering firm heading the project was paid US$3.4M to complete this study of the 4150km2 area containing over 650km of river reaches.

The first step in this huge undertaking involved the extraction of riverine cross sections (for dam failure modelling) and displaying the resultant water surface inundation areas through the use of BOSS RiverCAD. RiverCAD allows for the simultaneous use of the dam failure model (DAMBRK) and Digital Elevation Models (DEMs) to construct cross sections quickly and accurately. The results from the dam failure analyses were stored in AutoCAD format for electronic development of data, display of information, and printing of maps. Digital Raster Graphic (DRG) maps, scanned and geo-referenced images of standard quadrangle maps, served as a familiar base map for display. After the DAMBRK analysis was performed, the inundation areas were automatically overlaid onto the DRG base map through the use of RiverCAD’s Floodplain Mapping Module, one of the most useful snap-in tools available for the program. RiverCAD interpolated the edge of water between cross sections using DEM contour information.

A major element of the generation of inundation maps was the completion of a dam failure model. The DAMBRK model was used to predict dam failure wave formation and downstream progression due to a dam or dike failure. The DAMBRK model utilised input from riverine geometry in the form of cross sections to simulate the response of a flood wave travelling downstream. The outputs from the program provided hydraulic information at each river cross section. Information such as peak flows, maximum water surface elevations, arrival time of the leading edge, and maximum flood stage were used to identify key damage centers and other areas inundated by the flood wave.

RiverCAD consists of several program modules that integrate the functionality of AutoCAD and the added features of widely used programs such as DAMBRK and HEC-RAS to simplify the input and graphical display process. This makes digital generation of the riverine description and the subsequent generation of flood boundaries much simpler than with conventional means. The program allows users to cut cross sections digitally from Digital Elevation Model (DEM) maps and output the cross section geometry and the distance of the river cross section from the dam.

Digital Elevation Model (DEM) maps provide the topographic information that RiverCAD utilises to form representations of riverine cross sections. A DEM map is an array of elevation values at regularly spaced intervals. DEM maps are normally generated by sampling regular elevation values derived from topographic maps, aerial photographs and/or satellite images. The DEM map file is simply a text representation of ‘Z’ values (or elevation values) preceded by header information that specifies the spatial configuration (geo-reference) and separation of points. The accuracy of the elevation points varies depending on the source and manner in which the file was generated.

Within RiverCAD, the DEM Interface Module allows users to directly import a variety of DEM file formats. The DEM Interface Module automatically determines the map scale as the DEM map file is imported, and multiple maps can be imported and automatically merged. Once imported into RiverCAD, the DEM can be displayed as elevation contours at user-specified intervals. The ability to define contour ranges and intervals allows for the precise display of desired areas of topography for cross section generation.

Base maps: digital raster graphics

Perhaps the most recognised base map in use today is known as Digital Raster Graphics (DRG) maps. A DRG map is a raster image of a scanned topographic map georeferenced to the surface of the earth and fit to the Universal Transverse Mercator (UTM) projection to ensure horizontal and vertical accuracy. The DRG maps, scanned at a minimum resolution of 250 dots per inch, are generally complete with all full-colour base map information including topography, hydrography, and roadways.

An advantage to importing a DRG base map is having the opportunity to compare the generated contours of the DEM to the mapped contours of the original quadrangle. Ideally, the contours should match exactly. Differences can be caused by the accuracy of the DEM elevation point interval and spacing.

Once the base map overlay was set up for the Catskill and Delaware Watershed project, RiverCAD was used to digitally cut the cross sections. The user established the end points and any ‘bends’ in the cross section via on-screen digitisation using the contours generated from the DEM. The result is a 2D station/elevation cross section plot. RiverCAD preserved the geo-referenced accuracy of the DEM and base map to allow the user to pull DAMBRK top widths using RiverCAD’s distance measuring utilities.

After the DAMBRK model had been successfully completed, RiverCAD used the DEM as a basis for plotting the flood boundary. The program then interpolated the flood boundary between the cross sections. RiverCAD’s Floodplain Mapping Module interpolates the edge of water between cross sections. This allows users to see - in precise detail - which areas of the topographic map are flooded. RiverCAD is capable of plotting multiple flood boundaries to allow for the simultaneous display of fair weather and wet weather dam failure conditions. The program’s ability to manage, display, and format several layers of data facilitates the process - this key RiverCAD feature allowed for relative ease when editing, re-running, and producing final inundation maps of multiple dam failure scenarios.

Once the flood inundation limits had been plotted in RiverCAD, utilities could be used to apply finishing touches such as shading flood areas, formatting cross sections, etc. The finished product was a full-colour inundation map at a user-specified scale that fulfills guidelines for inundation map formatting.

One of the major advantages of using this digital mapping procedure is the ability to create full colour inundation maps using only RiverCAD. This simplified process increased the speed and efficiency of the mapping process, eliminating the need for antiquated hand-drawing of inundation boundaries, managing paper maps, and/or contracting an outside mapping company. Another advantage is the ability to produce a high quality, full colour final inundation map electronically. The electronic format of the map means making ‘last-minute’ or quick edits to the final map is greatly simplified.

RiverCAD also has the ability to export data as ESRI (Environmental Systems Research Institute) format data layers or shapefiles. ESRI format is synonymous with the ArcView/ArcGIS family of Geographic Information Systems software. ArcView is a geographic information systems (GIS) software application that is perhaps better suited than RiverCAD to handle geo-referenced data layers. GIS systems also offer the added ability to manage databases and merge information properties with graphic objects such as cross sections and flood boundaries.

Upcoming RiverCAD releases

The newest release of RiverCAD, RiverCAD XP, has been in development for over three years and is planned to be released within a couple of months. New features will include a more powerful CAD engine, integrated digital terrain modelling, a more sophisticated output viewer, and faster flood inundation mapping.

Also being released later this year is RiverCAD 2D, which can perform 2D dam failure analysis, 2D reservoir sedimentation modelling, and 2D river modelling. RiverCAD 2D can perform two-dimensional hydrodynamic modelling of a river system, allowing the engineer to route a complicated 2D dam failure flood wave downstream, accounting for the sedimentation and scour that also occurs during the event. Unlike with most models, the hydrodynamics of flow, sedimentation, and scour remain coupled during the simulation.

Boss International, 6300 University Avenue, Madison, WI 53562 US, http://www.bossintl.com

The Development of an ArcInfo Interface to the National Weather Service DAMBRK Model

by Michael Sebhat and Tom Heinzer

As a major water agency responsible for many dams in the Western United States, the U.S. Bureau of Reclamation (Reclamation) is mandated to develop flood inundation maps for many of its dams in the event of failure. Reclamation and local emergency management teams need to know where inundation might occur, arrival times, and flood wave speed and depth for various scenarios.

To this end, Reclamation's Mid-Pacific Region GIS Service Center (MPGIS) was tasked to develop a fully integrated GIS interface to the National Weather Service's DAMBRK (1) model. This paper discusses the methods used to integrate the ARCINFO, GRID, TIN, and NETWORK modules to develop a robust GIS driven hydrodynamic modeling environment that inundation specialists and hydrologists find very appealing and powerful. References to commercial products and services are included for discussion purposes only and do not imply an endorsement of services or products by Reclamation.

Defining Terms:

AML - ArcInfo Macro Language

ArcInfo - Esri GIS Software

Coverage - ArcInfo GIS layer

DAMBRK - The National Weather Service's DAMBRK FORTRAN model

DBI - DAMBRK Interface

DEM - Digital Elevation Model

Form Menu - AML driven Graphical User Interface

GRID - ArcInfo Raster module

MIKE21 - Danish Hydraulic Institute 2-D hydrodynamic model (2)

Reclamation - U.S. Bureau of Reclamation

TIN - ArcInfo TIN structure

USGS - United States Geological Survey

As part of its mission, Reclamation has the responsibility to manage, develop and protect water and water related resources throughout the Western United States. This also means providing for proper emergency planning in the event of a failure of any Reclamation facilities. As such, Reclamation is mandated to revise or create flood hazard maps relating to various dam failure scenarios. The Mid-Pacific Region GIS (MPGIS) office was asked to examine the possibility of creating an interface to the National Weather Service's DAMBRK model. NWS DAMBRK is a one-dimensional finite difference numerical hydrodynamic model designed to route water downstream of a given breach. DAMBRK predicts wave formation and subsequent downstream progression of that wave through a series of user defined cross-sections. It was written in FORTRAN in 1977 by Danny Fread and co-author Janice Lewis and has had subsequent upgrades. At MPGIS we have a strong belief that GIS technology has a lot to offer environmental models such as DAMBRK. The idea being that a GIS can readily integrate ancillary data during both model formulation and results analysis, which facilitates efficient decision making and, in our case, the creation of smart flood inundation maps. The DAMBRK Interface (DBI) functions as a pre and post processor, which uses the GIS to help create model input parameters, read model output files, and subsequently map the results. Examples of ancillary data for flood mapping include demographics, transportation, location of weirs, levees and other water conveyance systems, satellite imagery, aerial photography and digital elevation models (DEM).

DBI is a collection of AML macros, AML Form Menus, and UNIX scripts that enable a user to control a robust ArcInfo session which includes Arcedit, Arcplot, GRID, TIN, and Network modules working together. The user of DBI does not have to be technically proficient in ArcInfo to use it. A sound knowledge base of what ArcInfo is and what it can do is sufficient. DBI uses digital elevation models (DEMs) to construct the required cross-sections and subsequent parameters required for running DAMBRK. The user is essentially in Arcedit, using Arcplot drawing files (AP files) to view the DEM and all other ancillary data. The GRID, TIN and Network modules are used during the output processing steps. The original DAMBRK code was modified to output certain solution files in formats that ArcInfo can readily use. The output processing and viewing is primarily done in the raster realm (GRID), with vector ancillary data being added at will, including automatic contouring. Map generation of screen displays or creation of final report maps of flood events is built in. The entire operation of DBI is performed using AML built GUI Form Menus.

Components and Operation

There are six main components to DBI: build/edit cross-sections, populate model parameters, view input parameters, check/verify input and execute DAMBRK code, view model output grids, and make smart inundation maps. When a user begins a model the initial task is to build the cross-sections needed from near the dam to somewhere downstream along the river. To fully explain this procedure it is helpful to understand the basics of how DAMBRK itself works. The task of DAMBRK is to propagate a known amount of water through a series of user defined and internally formulated cross-sections and calculate water depth and flow at the cross-sections. The user can then view a selected set of six hydrographs from the model run. For each cross-section, up to eight levels of top-widths can be defined, each having a known length and a Manning coefficient. The DAMBRK wave propagates from one cross-section to the next in a downstream progression. A descriptive diagram is shown below in Figure 1.

The DAMBRK model has an internally generated series of cross-sections at specific intervals at which it will solve for stage and flow (in addition to the ones you specify). These internal solution cross-sections are commonly referred to as internal solution points. They are in between the user defined cross-sections. A simple configuration of this is shown on Figure 2 below.

It is desired to generate a mathematical cross-section that adequately approximates the actual one. The method being used in DBI allows the user to graphically 'drape' a transect on a DEM and the GIS automatically samples the DEM surface to create the cross-sectional profile (Figure 3).

When DBI is initiated, the main menu appears and guides the user to a specific cross-section building functions. Initially, the user clicks on the 'Add Transect' button. This brings up the cross-section builder menu and the associated graphics.

Once a transect has been 'draped' on a DEM, DBI presents the cross-sectional profile and switches to the cross-section parameter builder. The subsequent series of menus and graphics allow the user to develop the top-widths and to attribute the top-width lengths and elevations. The profile builder also has modules built in to allow the construction of flood plain and off line storage areas. Manually, this procedure would involve hours of drawing transects on USGS topographic maps and tediously constructing the cross-sectional profile on paper, and subsequently extracting elevation values observed at or near an elevation contour line. The DBI method of cross-sectional profile development is a much faster, more accurate and less time consuming process. Shown below in Figure 4 is the user's look-and-feel once optional flood plain and off-line storage areas are defined.

The number of top-width levels must be the same for all cross-sections. The DBI system is designed to be flexible and allow the user to add or delete top-width levels interactively until the desired configuration is reached. The on-screen look-and-feel is show below in Figure 5.

After the user has created the cross-section top-width data for all the transects, the DBI system will then build a relationship between all the cross-sections, the river centerline, and top-width descriptions. This facilitates the formation of the model input file required for DAMBRK. Before the user commits the input file to DAMBRK, the DBI system has some built in tools to scan the model scenario and detect missing items. This process performs a minimum requirements check on all user input, and as it finds problems, it reports them and allows interactive user corrections. In the early days of DAMBRK, computer cards were sill being used, and within DAMBRK there can be upto 66 parameter groups, thus there was a card for each group. In the DBI system, each one of these parameter group cards is represented by an AML Form menu. In most cases, not all 66 groups will be used. Consequently, to expedite parameter entry for a basic run of DAMBRK, the DBI system has a smaller menu to represent the most commonly used parameters. At any time the user can switch to the large 66 button menu. The basic menus include input/output control, headers, desired hydrographs, reservoir and breach parameters, cross-sections database, and model run time setup.

The model input file is constructed automatically by DBI and submitted to the DAMBRK model upon user request. This input file is formatted to be used for any NWS version of DAMBRK. This allows for data exchange and verification between many sites that might be involved in a given simulation. If the model runs and converges, the DBI system can then visualize output data (e.g. water depths, maximum inundation, etc.) using the output result files. The output generation is primarily done within the GRID, TIN and Dynamic Segmentation modules of ArcInfo utilizing AML and UNIX macros. The section following outlines the output generation.

Analysis and Display of DAMBRK Results.

In order to create inundation maps using DAMBRK results, it becomes necessary to map one dimensional model solution points (e.g. maximum water surface elevations) into a two dimensional surface which can be compared to the DEM to determine inundated areas. DAMBRK generates solution points both at the transects and at model generated transects. The model FORTRAN code was modified to write output hydrographs at all solution points, which enabled the mapping of these points along the river centerline utilizing event processing within the ArcInfo Dynamic Segmentation module. The transects are splined at a sufficiently small distance to create vertices along the transect. This facilitates a Dulaney triangle formulation that creates a linear interpolation between the roughly parallel transects when input to the TIN generator (Figure 6). The blue polygon shown in Figure 6 is the resulting inundated area.

The model generated points can also be used in the interpolation if so desired. DBI allows 'interpolation pseudo transects' to be added at these points, which may be used to introduce a region of influence that a specific point contributes (Figure 7). This ability can become relevant when flow courses deviate from linearity, and the need generally arises from the inadequacies of attempting to map one dimensional data into two dimensional space.

The resulting TIN surface is converted to a grid representing the interpolated water surface, which is compared cell by cell to the DEM surface using GRID map algebra conditionals to produce a water depth grid. A water depth result is shown for the Monticello Dam in California's Central Valley (Figure 8). This particular view includes the Yolo by-pass simulation calibrated to known flood conditions in 1986. The final transect output hydrograph of Monticello was injected laterally into the Yolo model.

All model results can be visualized directly in the interface. For example, maximum water depths may be presented using color remap tables overlaid on a hillshade. Other data may be subsequently added (Fig. 8). Hydrographs at user selected transects can be plotted (flow or stage vs. time). The hydrographs are generated entirely in ArcInfo. No outside graphing package is used (Figure 9).

Other Model results that can be visualized include maximum inundation, maximum water depths, maximum velocity and time to leading edge grids (ancillary procedures were developed for the leading edge calculations).

The DBI system also allows a user to generate time series based visualization. This added option produces all the required grids for a time series animation of the flood event. This becomes very useful in the planning of emergency response requirements at a given time. The option to drape maximum or time series based flood events is also built into DBI. The entire suite of TIN surface generation and draping tools are made available through Form menus.

We find that the DAMBRK model works well in areas where cross sectional profiles were well defined, usually in mountainous regions. However, in areas that open into large, unconfined valleys, such as the California Central Valley, a one dimensional modeling approach fails to adequately describe the two dimensional flows that occur. Additionally, levees become an important factor in low lying areas as they divert and delay the flood wave.

In these cases we have found it useful to implement a two dimensional model. MIKE21 (2), a finite difference engine, is currently being evaluated at MPGIS. MIKE21 facilitates the transfer of GIS data in and out of the model with relative ease. We manage the data on a GIS system, where we 'burn in' vector levee data onto the DEM. The DEM lattice spatially mimics the finite difference mesh. An example of the result of adding levees is shown in Figure 10.

Dambrk Software Online

Conceptually, the flood event propagates over the elevation lattice, being influenced by the terrain and the levee structures. The input hydrograph is obtained from a DAMBRK analysis. Model results are then brought into the GIS system for subsequent analysis and visualization. The Monticello Dam simulation processed with the MIKE21 model is show below in Figure 11. Note the zoomed inset showing the effect of levees around Davis, California.

Conclusion

Hydrologic models can benefit greatly when interfaced to GIS. Although development cost and time are issues, we feel the benefit of model data manipulation and functionality far outweigh these factors. Specifically, creating a GIS interface to the DAMBRK model has enabled us to:

• Generate scenarios much more rapidly.
• Make better decisions utilizing ancillary data.
• Implement scientific methods into a spatial analysis realm, and introduce reproducibility of interpolation procedures.
• More fully realize the limitations of the model.
• Introduce and understand assumptions more effectively

The use of USGS DEMs in the construction of DAMBRK top widths is a current topic of discussion in our agency. Clearly, the new 10 meter USGS DEM or interpolation of attributed hypsographic data is preferable. We have found, however, that while there may be some inaccuracies in the 30 meter DEMs in the local vicinity of hydrographic features, when modeling large scale inundation such as a dam breach (where >95% of the flow occurs outside the normal banks), the land surface where the majority of the water will reside is in general agreement with USGS topographic sheets ( usually less than two feet difference). In these cases, when considering other inaccuracies at the conceptual model level, the contribution of highly defined 'in bank' flow is arguably negligible. Additionally, if 10 meter USGS DEMs do not exist, the cost/benefit ratio may be too high.

The DBI system helped us realize that in many cases where a one dimensional model had been applied in past studies (ignoring levees, etc.), large errors were introduced due to numerous assumptions that had to be made. Although some one dimensional models allow for a rather eloquent handling of 'flood plain compartments', we found that in complex levee networks the procedure can be quite tedious, and in many cases impossible. After realizing a two dimensional model was required in many of our study areas, and since the GIS data we were using was easily transferable, preparing the simulation for MIKE21 input was academic.

For the two dimensional MIKE21 analysis, implementation of levees systems in the DEM are handled very well in a GIS. Varying Manning coefficients in two dimensions about the surface is well accommodated in a GRID environment. The ability to categorically breakout raster model output and convert it to polygon vector data for subsequent analysis in conjunction with other vector data sets can only be performed in a GIS. Finally, we feel through experience that modeling efforts, especially large scale endeavors such as those found in government agencies, are by far both more scientifically sound and cost effective in the long term when GIS systems are utilized effectively.

References

1. Fread. D.L. , The NWS DAMBRK Model: Theoretical Background/User Documentation. Revision 4, Dept. of Commerce, 1988.
2. MIKE21 User Guide and Reference Manual, Danish Hydraulic Institute, 1996
3. Bird, Byron R., Warren E. Stewart and Edwin N. Lightfoot. Transport Phenomena, New York, John Wiley & Sons, 1960.

Authors:

Tom Heinzer

MPGIS Consulting GIS Analyst, U.S. Bureau of Reclamation, 2800 Cottage Way MP-GIS, Sacramento, CA. 95825

Dark Software 7.55

Tel. (916)-979-2441 Email theinzer@mpgis2.mp.usbr.gov

Michael Sebhat

MPGIS Project Manager, U.S. Bureau of Reclamation, 2800 Cottage Way MP-GIS, Sacramento, CA. 95825

Http://barksoftware.net

Tel. (916)-979-2441 Email msebhat@mpgis1.mp.usbr.gov