The Fluvial Routing Analysis and Modeling Environment - FRAME - software is designed to simulate watershed and channel flow and sediment routing processes. FRAME comprises several model components connected by a control module that provides a graphical user interface and manages all data sets and operations. FRAME uses ArcView as front-end interface. FRAME features a collection of tools that includes among others landscape analysis, watershed segmentation, stream channel network extraction, computational mesh generation, and data conversion and viewing programs. The system is designed to simulate long-term effects of land use management practices and in-channel remedial and control structures on sediment yield and channel stability in disturbed watersheds.
FRAME - Fluvial Routing Analysis and Modeling - is a software package that integrates landscape analysis, watershed, channel hydrodynamics and channel morphology models. FRAME was developed as part of the Demonstration Erosion Control (DEC) Project, initiated by the Federal Government to develop and demonstrate methods and techniques to address watershed instability problems.
The simulation of watershed and channel processes requires a large amount of spatially distributed data, which include topographic description, soil data, land use, rainfall, and agricultural practices. The simulation models represent the study area by defining a channel network and subcatchments. Properties are usually assigned to the basic elements of this description: nodes (points), channel reaches (lines), and subwatersheds (polygons). FRAME was designed to simplify the preparation of input data used by the simulation models. The most tedious data preparation task is the definition of the channel network, subwatersheds, and the computational nodes required by the numerical models. FRAME automates the process, deriving the information from elevation data and transferring it to the simulation models. Starting from a Digital Elevation Model (DEM), FRAME creates the channel network and subwatersheds. Properties for each subwatershed are inferred from raster coverages through spatial analysis. The Graphical User Interface (GUI) provides a convenient means of data input for nodal properties such as cross section geometry, bed and bank material properties and in-stream hydraulic structures.
FRAME was developed as an extension to the Geographic Information System ArcView® (Esri, 1996). A control module provides a single, consistent GUI that manages the modeling components, all data sets, and operations (Vieira, 1997, Vieira et al, 1998).
Figure 1 - FRAME Interface Layout
FRAME creates an environment that guides the user through the modeling process in four distinct areas:
Graphical User Interface: A single, uniform GUI presents the options available at each step of the modeling processes. The GUI elements are designed so that they are available only when necessary, reducing the number of menus and buttons to avoid confusion and clarifying what the user should do next. FRAME organizes the data, and stores documents (maps and tables) that reflect the output of the models in a manner that the user can readily identify and use. FRAME creates specialized GUIs for the several types of documents it creates or displays.
Data Management: The integrated numerical modeling of watershed and channel processes requires the use of several models, which were developed independently and not necessarily designed to be employed in an integrated fashion. These models require a rather large amount of input data, and usually the output of a model is used as the input for another. FRAME creates and maintains a database where all information is stored. Data transfers between the modeling components are automatic, which substantially reduce the amount of information handled by the user. FRAME executes several types of data conversions and other tedious and error-prone tasks.
Operations Control: FRAME controls all steps of the simulation process. Before a simulation model is started, FRAME retrieves the input data from its database, checks for consistency, and performs data conversion if necessary. FRAME then starts the simulation module providing all the required input data.
When the simulation is complete, FRAME appends the results to its database and displays the relevant information in the form of graphics.
Visualization Tool: FRAME's visual capabilities allow the user to immediately see the data in form of maps and tables. FRAME displays watershed, channel networks and Digital Elevation Models (DEMs) as maps. A series of tools is being developed to display modeling output data in various formats of plots and graphs, which will include the capability of producing animations.
FRAME distinguishes four steps in the simulation of watershed and flow routing problems. The Landscape Analysis phase deals with the automatic extraction of the channel network and the delineation of subwatersheds. FRAME uses TOPAZ - TOpographic PArameteriZation - a landscape analysis tool for identification of channels and subcatchments of drainage networks (Garbrecht and Martz, 1995). The Watershed Analysis is performed by SWAT - Soil and Water Assessment Tool - a computer model that simulates continuous watershed processes on a long-term basis with a minimum amount of user-defined input data requirements (Arnold et al., 1993). The Channel Network Analysis part is entirely implemented within ArcView. FRAME is able to create a computational mesh based on the channel network extracted by TOPAZ. This module also manages most of the input data for the channel flow and sediment transport models. The final step is the Channel Flow and Sediment Transport Analysis. The flow model DWAVNET - Diffusion WAVe model for channel NETworks - simulates the long term, continuous runoff from storm events (Langendoen, 1996). The sediment transport model BEAMS - Bed and bank Erosion Analysis Model for Streams - simulates the dynamic response of streams to natural and man-induced changes in the watershed (Langendoen et al, 1998; Zhang and Langendoen, 1998). FRAME controls both models, supplying the necessary input data from its database.
Avenue scripts of the FRAME extension control all operations and user interaction. When the extension is activated, the user is prompted for a Case Study name. FRAME creates a directory (folder) in which all data for that particular case will be stored. Since a FRAME simulation project may contain more than 100 files, new directories are created inside the case directory to store data from user input and from the simulation models. FRAME maintains a tight control of all data, the location of the corresponding files, history of operations, and relationships among the data sets. The FRAME GUI hides all these operations from the user. The GUI displays the contents of the project in groups organized according to the type of data. Currently these groups are DEMs, Channels, Subwatersheds, and Database.
FRAME also keeps an internal database to store information about the contents of the project. This database also stores data about supported data types, naming conventions, default values, etc. It is created when a new case study is defined, and automatically maintained from then on. This database is accessed by most of the FRAME scripts. Its contents are saved within the project file as an ArcView object database (ODB). This allows the user to interrupt work on the project, save and close the project, and later return to work without any loss of information.
FRAME pays special attention to the map views. Map themes are created with predefined colors and symbols. The user may choose from predefined legends or use the powerful legend editor of ArcView.
Figure 2 - Document Groups and Channel Network Map
FRAME provides the capability of extracting channel network and subwatershed information from a DEM. The FRAME GUI controls the user interaction with the landscape model TOPAZ. Before the channel extraction algorithm is applied, the DEM is pre-processed to ensure that a convergent network of flow paths can be generated.
Pits and depressions are eliminated by either filling them to the elevation of their local outlets, or by lowering the elevation of cells that obstruct the flow path. In the latter case, the user can specify the thickness of a blockage that makes the depression an artifact of the DEM, and not a geographical feature. Usually, blockages caused by imperfections of the DEM are one or two cells thick. TOPAZ identifies these blockages and decreases their elevations, avoiding the filling of a larger area. After depressions are removed, flat areas are eliminated by imposing a relief that is based on the topography of the surrounding terrain.
The GUI provides for the input of options and parameters for this pre-processing, and it displays the original and processed DEMs as TIFF images with a variety of 256-color ramps.
After the DEM is processed, FRAME provides a GUI to guide the user through the process of extracting the channel network. The appearance of the channel network (channel density, minimum channel lengths, subwatershed areas) is controlled by two calibration parameters. These parameters can be constant throughout the DEM, or combinations of parameters can be applied to different regions defined in a separate raster map. The FRAME interface provides means to create several sets of the channel extraction parameters, so several sets can be applied to the same DEM, or conversely, the same set can be applied to more than one DEM. At any moment the user can create, edit or view the extraction parameter sets.
FRAME allows the extraction of several channel networks within the same ArcView project, so that they can be displayed side by side for comparison.
Future enhancements to the channel network generation module include the digitizing of the network elements from imagery (digital maps or photographs), with automatic creation of the network database.
Figure 3 - Extracted channels, computational channels and subwatersheds
FRAME extends TOPAZ by creating a relational database to store the channel network and subwatershed data. This database eliminates the need of referencing large, computer resource demanding, raster maps. FRAME converts the raster information into vector maps associated with database tables.
The tables store data related to each of the entities that compose the channel network: Nodes, Reaches, Links, Channels, Subwatersheds and Incremental Areas. FRAME manages the data relationships between these tables, updates their contents and verifies their integrity. A Node is a point in the network that represents a special feature, such as beginning and ending points of channel segments, channel junctions, points of water and sediment inflow, and hydraulic structures. Reaches, Links and Channels are used to describe channel segments and their inter-relationships. A Reach is simply a channel segment between two nodes. Links are containers of either Reaches or Hydraulic Structures. Channels are containers of Links, and represent the natural division of the network into streams. Only nodes and reaches have graphical representation. The other entities are used for network analysis purposes.
FRAME adopts the definition of the subwatersheds performed by TOPAZ, but it creates further sub-divisions called Incremental Areas, which are drainage areas that correspond to channel segments between two nodes (reaches). The purpose of the Incremental Areas is primarily computational. They are used to relate overland flow to computational nodes in the channel network.
Figure 4 - Conceptualization of the FRAME Channel Network Database
The FRAME database is designed to store all input properties for the channel flow and evolution models. Additional data include cross section geometry, bed and bank sediment properties, and hydraulic structures data. FRAME creates graphs showing the channel network, computational nodes, and hydraulic structures, which are stored as shapefiles. The database tables can be used in conjunction with the shapefiles to increase the flexibility of the graphical output. Data from any record or field of the database are readily available and can be queried or used directly in any graph.
FRAME provides many tools to help the user prepare the input data and control the flow routing and sediment transport simulations. These tools can be grouped into two categories:
Channel Network Definition - Tools employed in the description of the channel network elements that form the computational mesh, such as channel segments, computational nodes, subwatersheds, channel junctions and the location of hydraulic structures.
Data Management - Tools dealing with data not considered as part of the channel network itself, but required for the numerical analysis. These data includes cross section geometry, hydraulic structure characteristics, and bed and bank material compositions.
FRAME automatically extracts the channel network and subwatersheds from a DEM. It also creates a logical description of the network elements and their mutual relationships, defining how nodes and reaches are connected and how they should be treated in the numerical computations. However, the simulation models require a more detailed topological description of the simulation domain. This spatial discretization depends on the characteristics of the numerical analysis methods.
FRAME is capable of automatically defining a computational mesh that adequately describes the channel network, ensuring that it meets the requirements for numerical stability and accuracy imposed by the models. The user can also define the computational mesh interactively, and tools for adding nodes to the computational mesh are provided.
In order to guide the user through the process of computational mesh generation, a new map view is created based on the current data. The new window has interface elements that allow for all operations of the mesh generation and control of the flow and sediment transport models.
A channel network as extracted from a DEM has very few nodes. The nodes only identify the beginning of channels and channel junctions. Furthermore, the irregular spatial distribution of the nodes makes the channel network inadequate for the numerical computations. The simulation models DWAVNET and BEAMS impose restrictions on channel lengths and on the uniformity of their distribution in the network.
FRAME has an analysis model that inspects the channel network for possible improvements to create a computational network that fulfills the requirements of the flow and sediment transport models. The analysis applies a set of pre-defined rules that determine the number and location of computational nodes that should be added to the channel network. Currently, three rules are used to analyze the network.
The first rule verifies the variation in flow area between consecutive nodes. FRAME estimates representative flow areas for each node based on the geometric characteristics of its cross section. For reaches where important variations in flow area are predicted, FRAME inserts extra nodes, so that the variations in flow area from one node to the next are reduced to acceptable values.
FRAME analyzes all channels in the network to determine if the distribution of channel reach lengths is reasonably uniform. Large variations in node spacing along a channel reach may negatively affect the quality of the numerical simulations. A series of local and global representative lengths is computed, and long reaches exceeding the representative lengths are split in order to make the spacing of computational nodes more uniform.
Finally, FRAME inspects the neighborhood of channel junctions and hydraulic structures. The flow and sediment transport models employ specialized algorithms to compute the flow properties at these locations. FRAME ensures that the model requirements are satisfied by locally refining the computational mesh.
Figure 5 - Extracted and Computational Channel Networks
When creating a computational mesh, the user can add nodes to the channel network by simply clicking on the channel network map. Nodes can be inserted to fine-tune the mesh created by FRAME or to ensure that flow and sediment properties will be computed at locations of special interest.
The addition of nodes alters the topology of the channel network, which requires that many of the database tables be modified. When either the user or FRAME defines the position of a new node, the reach where the node is located is split into two. The reach shapefile is modified to reflect the graphical representation of new reaches. FRAME recalculates reach properties such as length and slope, and the node numbers are updated. The subwatershed is also subdivided, and a new incremental area that corresponds to the new node is created.
FRAME provides a collection of graphically-oriented tools to help the user to input the wealth of information required by the simulation models. Data supply and editing operations are performed using the Extracted Channel Network map.
The user can utilize the provided options to easily supply, edit and visualize the input data. Inputting information consists of simply selecting a node and entering data in the input fields of the dialogs that appear. FRAME verifies the input data for errors and completeness, and provides interpolation and data propagation methods to reduce the amount of information the user has to enter.
When data is entered, FRAME automatically creates the necessary database tables and establishes the relationships between the input data and the database that describes the channel network. FRAME updates the database to reflect changes due to the user action through the graphical interface.
FRAME simplifies the procedure of data entry by providing a simple, flexible graphical interface. The user does not need to be concerned with details of input data formatting, conversions, or relationships between the data and the channel network elements (nodes and reaches).
The flow routing model requires that the channel cross section geometry be known at all computational nodes. A channel network may have hundreds of nodes, and the user rarely has information available for all these nodal points. FRAME uses linear interpolation to supply information for nodes without data. The user is required to supply data only for the nodes at the upstream and downstream ends of each channel.
FRAME automatically creates a database table to store the information. This table is related to the table containing data about the nodes. By using ArcView's database support capabilities, the analysis routines of FRAME are able to update the cross section table and provide access to the table through the channel network map.
The user may supply the cross section data by selecting a node in the channel network map and filling in the appropriate fields when prompted by the program. Alternatively, the user may choose to import an existing database table with cross section information, or import the available data in the form of an ASCII flat file. FRAME verifies the data being imported, and can visually display the nodes for which information is still missing. If erroneous records are present in the imported table, FRAME stores these records in a separate table, so they can be corrected by the user.
The interpolation procedure is automatic. If the user did not specify data for a certain cross section, FRAME will search for the nearest upstream and downstream nodes with known cross sectional properties and perform the interpolation. FRAME will not perform the numerical simulations if cross section data is unavailable at the ends of a channel.
The cross section data can be modified using the various editing options. The user can select a particular node for editing and modify the fields in the accompanying dialog. There is also an option for directly editing the database table.
FRAME implements the cross section description scheme of DWAVNET, in which the cross sections are of trapezoidal shape, and are subdivided into main channel, left and right floodplains.
FRAME composes a special channel network map where the user can interactively add hydraulic structures to the channel network. The models DWAVNET and BEAMS support four types of structures: culverts, measuring flumes, drop structures and bridge crossings (piers and abutments).
The user can set the location of these structures by simply clicking on any point of the channel. When a structure is added to the network, the user is asked to enter its characteristics. FRAME provides options for data editing similar to those for cross section data. FRAME can also import a file containing the data for the hydraulic structures.
Hydraulic structure data are stored in several database tables. There is one table for each type of structure present in the network. A master table stores the type and location of all structures. The master table is also responsible for relating the structure tables to the FRAME network database.
The models DWAVNET and BEAMS treat hydraulic structures as a set of three nodes that share the same location. These nodes are used in the solution of the equations that describe the hydraulic behavior of a particular structure. The insertion of structures produces important changes in the logical description of the channel network. FRAME automatically updates all the database tables, similarly to the addition of nodes. Hydraulic structures also affect the definition of Links, since each structure is a link itself.
Figure 6 - Hydraulic structure (culvert) input data interface
FRAME provides a graphical interface for the management of bed and bank sediment properties, required by the sediment transport and erosion model BEAMS. Sediment data must be provided for each nodal point of the network. Like DWAVNET, BEAMS utilizes three regions for each cross section: main channel, and left and right floodplains. Sediment properties must be specified for each region. Sediment properties are also divided into Bed and Bank zones.
The algorithms of BEAMS will estimate transport, erosion, and deposition based on local flow properties and on the sediment composition of the various cross section regions. BEAMS will update the sediment composition to reflect the changes due to erosion or deposition.
Data input for sediment properties is essentially similar to the input of cross section data. The same functionality is provided. FRAME also allows the specification of sediment data by importing text or database files.
When bed or bank sediment data are entered, FRAME creates database tables to store the data. Bed and Bank Sediment tables store records that describe general properties of the sediment. Both tables are related to the Node table of the channel network database. Usually, the sediment data available to the modeler are sparse and scattered over the watershed, and similar properties are specified to many nodes of channel network. FRAME does not store duplicate records in the database.
The sediment composition for each sub-region of the cross section is stored in the form of percentage fractions that belong to a pre-defined grain size class. These fractions are stored in the Grain Distribution table. The Bed Sediment table refers to records of this grain distribution table for the sediment compositions of the main channel and floodplains. Similarly, the Bank Sediment table refers to the grain distribution table for the composition fractions for the left and right banks.
Currently, the interface to the watershed model SWAT is the Blackland SWAT-GRASS interface (Srinivasan et al, 1996). FRAME starts the SWAT-GRASS program and exports the DEM and Subwatershed data as raster maps. The SWAT-GRASS program uses the GRASS GIS to perform all the spatial analysis and extract properties for each subwatershed. Input data for SWAT consists of the DEM, subwatershed map, land-use map, soil map, and data about climate and agricultural practices. The SWAT-GRASS interface creates a series of data files to store the derived information.
FRAME starts the SWAT simulation, which computes water and sediment runoff for each subwatershed. The results are used as input to the channel flow models DWAVNET and BEAMS.
A fully integrated ArcView interface for SWAT is currently under development at the Texas Agricultural Experiment Station - Blackland Research Center, Temple, Texas. This interface uses the ArcView Spatial Analyst extension to perform spatial modeling and database access operations. Integration of the Spatial Analyst interface to FRAME is expected for the second half of 1998.
The FRAME interface provides the necessary functionality for the input of options and parameters for the flow and sediment transport models. Since FRAME performs many tasks automatically, its database stores practically all the information needed to run the models. When the user starts the simulation from the interface, FRAME gathers all the data from its database and creates a file with instructions to the models. This file contains the location of all data files, data introduced through the interface, and options that reflect either user choice or automatic setting by the FRAME control module.
FRAME also starts the channel flow and sediment transport simulation. When the simulation is complete, FRAME can upload results for visualization.
Modeling of a watershed system involves the tedious process of assembling a large database from varied sources. The collected data are rarely complete and ready for use by the simulation models, requiring effort to supply missing information and convert the data to formats suitable to the models. FRAME attempts to reduce this workload by integrating several data sets into a common database, analyzing the available data to produce new information, and by performing the necessary conversions. FRAME provides a convenient graphically-oriented interface for data entry and checking. Furthermore, the interface guides the modeler, clarifying the sequence of operations and the available options.
The design of FRAME foresees the inclusion of other modeling components and tools. Data input will be improved by providing the user with digitizing capabilities and support for scanned and satellite images. The visualization of output data will be enhanced by the automatic production of maps, graphs, summary tables, and reports. Planned extensions to FRAME include water quality and groundwater simulation models.
This work is a result of research sponsored by the USDA - Agricultural Research Service under Specific Cooperative Agreement No. 6408-13000-008-01S (monitored by the USDA-ARS National Sedimentation Laboratory), and the Center for Computational Hydroscience and Engineering at the University of Mississippi.
Arnold, J.G., Allen, P.M., Bernhardt, G., 1993, A Comprehensive Surface-Groundwater Flow Model, Journal of Hydrology, 142, 47-69.
Environmental Systems Research Institute, Inc., Esri, 1996, Avenue. Customization and Application Development for ArcView, Esri, Redlands, California.
Garbrecht, J. and Martz, L.W., 1995, An Automated Digital Landscape Analysis Tool for Topographic Evaluation, Drainage Identification, Watershed Segmentation and Subcatchment Parameterization, Report No. NAWQL 95-1, National Agricultural Water Quality Laboratory, USDA, Agricultural Research Service, Durant, Oklahoma.
Langendoen, E.J., 1996, Discretization Diffusion Wave Model, Tech. Rep. No. CCHE-TR-96-1, Center for Computational Hydroscience and Engineering, The University of Mississippi, University, Mississippi.
Langendoen, E.J., Bingner, R.L., Kuhnle, R.A., 1998, Modeling of Long Term Changes of Unstable Streams, Proc. First Federal Interagency Hydrologic Modeling Conference, Las Vegas, Nevada.
Srinivasan, R., Byars, B.W., Arnold, J.G, 1996, SWAT/GRASS Interface Users Manual, version 96.2, Texas Agricultural Experiment Station, Blackland Research Center, Temple, Texas.
Vieira, D.A., Langendoen, E.J., Bingner, R.L., 1998, FRAME - An Integrated Modeling System of Channel and Landscape Processes, In Proc. First Interagency Hydrologic Modeling Conference, Las Vegas, Nevada.
Vieira, D.A., 1997, FRAME - Control Module Technical Manual, Tech. Rep. No. CCHE-TR-97-7, Center for Computational Hydroscience and Engineering, The University of Mississippi, University, Mississippi.
Zhang, Y. and Langendoen, E.J., 1998, An Introduction to BEAMS (Bed and Bank Erosion Analysis Model for Streams), Tech. Rep. No. CCHE-TR-98-2, Center for Computational Hydroscience and Engineering, The University of Mississippi, University, Mississippi.
Dalmo A. Vieira
Research Associate
Center for Computational Hydroscience and Engineering, The University of Mississippi
University, MS 38677
http://hydra.cche.olemiss.edu/frame
Eddy J. Langendoen
Research Hydraulic Engineer
USDA-ARS - National Sedimentation Laboratory
Oxford, MS 38655
Ronald L. Bingner
Agricultural Engineer
USDA-ARS - National Sedimentation Laboratory
Oxford, MS 38655