General Information:

Disclaimer
Latest information
Topaz purpose and objectives
Some significant features of TOPAZ
Capabilities and limitations
Input requirements
Output information
Examples of TOPAZ applications
Future developments
About the authors
Literature References on TOPAZ
Full Papers on TOPAZ
News Releases
Useful links

DISCLAIMER

The programs and subroutines of TOPAZ are accepted and used by the recipient upon the express understanding that the developers make no warranties, expressed or implied, concerning the accuracy, completeness, reliability or suitability for any one purpose, and that the developers shall be under no liability to any person by reason of any use made thereof.

The programs and subroutines of TOPAZ should be used as a self-contained software system. The data processing in one subroutine is dependent on the processing by prior subroutines. Therefore individual subroutines and code sections cannot be lifted, extracted or transferred out of this TOPAZ software for use in other programs. Such a use may produce erroneous results that may go unrecognized.

The ARS and developers of TOPAZ shall be acknowledged when the code, the model and/or the numerical solution techniques in TOPAZ are used, described or referenced in a publication or presentation.

Latest Information

• TOPAZ Version 3.12 is now available. Changes from TOPAZ Version 3.11 include streamlining of selected portions of the code for faster execution with very large DEMs, and a modification to the Global Slope calculation for subcatchments to account for special channel/subcatchment configurations.
• The Windows executable programs of TOPAZ Version 3.12 have been compiled with code optimization and should run faster than the previous Version 3.11, for most applications.
• Note for TOPAZ applications to very large DEMs (<4,000,000 cells) with the windows executable TOPAZ code in directory Winexe. Due to compiler limitations in memory allocation/paging, the user must insure that adequate RAM memory is available for processing large DEMs. Program RASPRO is particularly sensitive to RAM memory limitations. If you encounter memory allocation problems (often listed as "access error"), you should try to run TOPAZ with the aggregation/resampling feature described in input file DNMCNT.INP. We are currently working to overcome this problem. A windows executable TOPAZ code with full virtual memory capabilities will be made available as soon as possible. Alternatively the user can compile the TOPAZ source code with their own FORTRAN90/95 compiler.

• TOPAZ Version 3.11 is now available. Changes from TOPAZ Version 3.10 include a number of output format revisions to accomodate values associated with very large DEMs and/or very large cell sizes.
• A draft User Manual for TOPAZ Version 3.1x is available on the TOPAZ Homepage. A final User Manual for TOPAZ Version 3.1x will be available in December 1999 for direct downloading from our FTP site.

• TOPAZ version 3.10 is now available in: (1) ASCII format (for user compilation with a FORTRAN90 compiler); and (2) executable format for application with Windows 95 and 98. Please check the "TOPAZ Distribution" section on how to obtain your copy of the code and manuals. A brief description of TOPAZ Version 3.10 is given in the "TOPAZ Versions" section. Please note that TOPAZ Version 3.10 supersedes TOPAZ version 3.00.

• TOPAZ version 3.10 is expected to be released around June 1999. This version will include calculations of representative area, slope and length values for the subcatchments within a watershed. In addition, minor code changes to accommodate a larger range of FORTRAN90 compilers are also implemented.
  TOPAZ version 3.10 will supersede version 3.00.
  

---

TOPAZ
Purpose and Objectives  

---

TOPAZ is an automated digital landscape analysis tool for topographic evaluation, drainage identification, watershed segmentation and subcatchment parameterization. While TOPAZ is designed primarily to assist with topographic evaluation and watershed parameterization in support of hydrologic modeling and analysis, it also has application to a variety of geomorphological, environmental and remote sensing investigations.

The overall objective of TOPAZ is to provide a comprehensive evaluation of landscape drainage characteristics while maintaining consistency between all derived data, the initial input data, and the physics underlying energy and water flux at the landscape surface. The analysis is based on the application of the deterministic eight-neighbour (D8) method to simulate flow across a land surface represented by a raster (grid) digital elevation model.

---

TOPAZ
Significant Features

---

TOPAZ effectively handles drainage identification in the presence of depressions and flat areas in the input DEM by using an innovative combination of depression outlet breaching, depression-filling, and relief imposition. This feature is particularly effective when analyzing low relief landscapes with DEMs of limited resolution.

TOPAZ has the capability of generating spatially varying drainage densities and subcatchment areas. This is accomplished by varying the user-controlled parameters of Critical Source Area (CSA) and Minimum Source Channel Length (MSCL). This capability is useful to capture the effect of variable geology across the watershed on drainage density and subcatchment size.

TOPAZ identifies the topology of the channel network by assigning numbers to the channel links, junctions and subcatchment areas, and identifying the connectivity of the channel network. This includes the computation of the optimal sequence to perform cascade flow routing through the channel network. This feature provides fundamental information for hydraulic/hydrologic models that perform flow routing.

TOPAZ includes a comprehensive channel network analysis capability. This capability provides network and subcatchment statistics, as well as morphometric parameters of channel network composition. The channel network analysis is performed for both the generated raster network, as well as a network that has been corrected for biases associated with DEM resolution.

TOPAZ computes representative values for subcatchment properties that are distributed in nature and for which a single, absolute value does not exist. For example, representative travel distance for an irregular subcatchment must be approximated based on the various travel distances within the subcatchments. The capability of computing representative subcatchment properties is particularly useful for lumped-distributed hydrologic model applications.

TOPAZ generates raster output files of the drainage network, subcatchment areas and a variety of drainage-related topographic variables. These can be easily imported by most Geographic Information Systems (GIS) for display, registration to other data coverages and spatial analyses.

TOPAZ generates a series of tabular output files that provide the properties of individual channel links and subcatchments, as well as information on the overall channel network structure. These tables are for user analysis or input into traditional distributed hydrologic models.

• User provided input files for program DEDNM
  General input file DNMCNT.INP
  DEM input file DEDNM.INP
  Network generation input file NTGCOD.INP
  
• User provided input file for program RASPRO
  Raster reprocessing input file RASPRO.INP
  
• User provided input file for program RASFOR
  Raster reformatting option file RASFOR.INP
  
• User provided input file for program PARAM
  Subcatchment parameterization input file PARAM.INP
  

In addition to the input files that are provided by the users, each of the programs in TOPAZ requires input files that are generated internally. Topaz generates and reads these files automatically, without any action by the user.

General input file DNMCNT.INP
File DNMCNT.INP is the input file which defines DEM raster characteristics, DEM processing options and corresponding parameters, as well as user output options. The following provides a more detailed list of the parameters in this input file.

*** General information

The information consist of a title for the current application which will be printed in tabular, evaluation and report files generated by TOPAZ. 
 

*** DEM raster characteristics

The basic characteristics of the input DEM consist of : optional UTM coordinates if known; number of rows and columns of the input DEM; minimum and maximum elevation values of the input DEM; elevation values that identify indeterminate elevations; orientation of the DEM; and, approximate or estimated row and column number that defines the watershed outlet.
 

*** DEM processing options and parameters

Processing options include options for reduction of the input DEM by aggregation or resampling , the smoothing of the DEM, and, the breaching/depression filling option. In addition, Critical Source Area (CSA) and Minimum Source Channel Length (MSCL) parameter must be provided. A user option is also available to perform a detailed raster quality control/error checking.
 

*** User output options

The user output options define the desired tabular and report output files from TOPAZ.

top

User provided DEM input file DEDNM.INP

File DEDNM.INP is the file which contains the elevation data of the DEM. The unit of elevation is meters, and the precision with which the values are read is 1/10th of a meter or one decimeter. Any additional precision in the elevation input is rounded to the nearest decimeter. The minimum and maximum elevation values accepted by TOPAZ are 1.0 and 9999.0 meters, respectively. Sometimes not all elevation values in a DEM are relevant or known. In these cases a characteristic value that designates indeterminate elevation must be provided. This value can be any value outside the range of the minimum and maximum values given above. A recommended value for indeterminate elevation is 0 (zero) or -1.0. The format of the elevation data is one value per record, ordered column first, row second. Two displays of DEM elevation data are available: one is a 2-dimensional display of the elevations, and the other is a 3-dimensional perspective display of the elevations

top

Network generation input file NTGCOD.INP

File NTGCOD.INP is the file which contains the spatial distribution and value of the network generation codes. The spatial distribution of the codes reflects the spatial variability of geophysical landscape properties that are relevant for the generation of the drainage network and watershed segmentation to exhibit spatially variable characteristics. The user can select up to 5 code values. Each code value corresponds to a user defined Critical Source Area (CSA) and Minimum Souce Channel Length (MSCL) value as given in input file DNMCNT.INP. The format in which the codes are provided is one value per record, ordered column first, row second, in exactly the same way as for input file DEDNM.INP.

The input file NTGCOD.INP is not needed if the user elected to use only one CSA and MSCL value for the entire DEM.

top

Raster reprocessing input file RASPRO.INP

File RASPRO.INP contains raster reprocessing and user output options for program RASPRO.  Options include reprocessing data for depression and flat area locations (display), reclassification into bands of equal elevations (display), calculation of local slope and aspect, and network and subcatchment display enhancements (display).
 

top

Raster reformatting option file RASFOR.INP

File RASFOR.INP contains user output options and format for raster files. User format choices include ARCINFO format, IDRISI version 4.0 format, ASCII 2-dimensional format and ASCII 1-dimensional format. Any or all of the raster files provided by TOPAZ can be selected for output.

top

Subcatchment parameterization input file PARAM.INP

File PARAM.INP contains user output options for subcatchment parameterization.

The output from TOPAZ consists of tree different types of files:

• Raster output files
  General description and types of raster files
  List of files and content description
• Tabular output files
  General description
  List of files and quantified variables
• Evaluation output files
  General description
  List of files and evaluated parameters
   

Raster output files

General description and types of raster files
Raster data are used to represent spatially varying watershed characteristics, such as topography, drainage boundaries and network configuration, and distributed land surface attributes. The raster data can be imported into a GIS for display, overlay analysis and/or further processing. Initially all raster output files are written as FORTRAN unformatted files (binary) and are given extension .out. Subsequently, these files may be reformatted by program RASFOR into one of four format options: ASCII 1-D, ASCII 2-D, IDRISI and ARCINFO.

- ASCII 1-D
ASCII 1-D files are formatted (user readable) files that have one value per record. The order of the values are column first, row second. ASCII 1-D files have the extension .DAT.
- ASCII 2_D
ASCII 2-D files are formatted (user readable) files that have multiple data entries per record. Each record contains the data of an entire row of the raster file. Thus, record 1 contains all the column values in the first row of the raster, record 2 the data of the second row, etc. ASCII 2-D files have the extension .DAT.
- IDRISI
Files in IDRISI format can be directly imported into the commercial GIS package IDRISI. The files come in pairs: one image file (extension .IMG) and one corresponding documentation file (extension .DOC). The image and documentation files are fully compatible with IDRISI Version 4.0.
- ARCINFO
Files in ARCINFO format can be directly imported into the commercial GIS package ARCINFO.  ARCINFO files have the extension .ARC.

A list of raster output files, including content description is provided below.

top

List of files and content description
The following is a listing of raster files, including a short description of the content.

Output from program DEDNM:

- BOUND.OUT:   Boundary of the watershed upstream of a user selected watershed outlet.
- FILDEP.OUT:  DEM after removal of depressions and pits by a breaching-filling operation.
- FLOPAT.OUT:  Beginning, ending and transition cells of drainage flow paths.
- FLOVEC.OUT:  Drainage directions at each cell.
- INDTAR.OUT:  Identification codes of cells in the DEM that are areas of defined/indeterminant elevation or adjacent to areas of indeterminant elevation.
- INELEV.OUT:  Digital Elevation Model (DEM) of the landscape as provided by the user.
- NETFUL.OUT:  Channel network for the entire DEM.
- NETW.OUT:    Channel network within watershed boundary.
- NTGCOD.OUT:  Identification of the areas corresponding to different channel network generation parameters to represent spatial variability of the channel network.
- RELIEF.OUT:  DEM after removal of all depressions and after relief imposition on flat areas.
- SMOOTH.OUT:  DEM after optional user selected smoothing.
- SUBWTA.OUT:  Subcatchments identification (right, left, source and channel) corresponding to the generated channel network.
- UPAREA.OUT:  Upstream drainage area.

Output from program RASPRO:

- DEPFLT.OUT:  Location and extent of depressions and flat areas in the DEM.
- ELVCLA.OUT:  Reclassified elevations into bands of equal elevation.
- ELDCHA.OUT: Elevation drop from each cell defined in the watershed to the next channel.
- ELDOUT.OUT: Elevation drop from each cell defined in the watershed to the watershed outlet.
- DISCHA.OUT: Distance from each cell in the watershed to the next channel.
- DISOUT.OUT: Distance from each cell in the watershed to the watershed outlet.
- FVASPEC.OUT: Aspect of the drainage direction (8 possible directions).
- FVSLOP.OUT:  Slope of the outflowing drainage direction.
- HSLOPE.OUT:  Average slope of the inflowing and outflowing drainage direction.
- NETWE.OUT:   Widened channel network for enhanced display.
- SUBBDA.OUT:  Boundaries of the subcatchments.
- SUBWTB.OUT:  Aggregated subcatchments identification (right, left and source area combined) corresponding to the generated channel network.
- SUBBDB.OUT:  Boundaries of aggregated subcatchments.
- TASPEC.OUT:  Aspect of the terrain (from mathematically fitted surface).
- TSLOPE.OUT:  Slope of the terrain (from mathematically fitted surface).

top

Tabular output

General description
Tabular output files provide a tabular listing of channel and subcatchment attributes, such as channel length, channel slope, channel network junction information, subcatchment area and other related attributes. They contain data that is often needed in hydrologic applications and distributed models of land-surface processes. The following is a listing and description of attribute files produced by software TOPAZ.

List of files and quantified variables

Tabular output of program DEDNM:

• Netw.tab:    Contains channel link information for the raster network.
  • Channel link index.
  • Index of upstream inflowing channel links.
  • Index of downstream channel link.
  • Channel link node code (source, junction or outlet).
  • Rearranged sequence of channel links for cascade type flow routing.
  • Strahler channel link order.
  • Coordinates of the beginning and ending point of a channel link.
  • Elevation of the beginning and ending point of a channel link.
  • Channel link length.
  • Channel link slope.
  • Upstream drainage area at the beginning and ending point of a channel link.
  • Direct drainage area into a channel link.
    
• Sbct.tab:      Contains subcatchment information for the raster network.
  • Subcatchment index.
  • Strahler order of the channel link the subcatchment drains into.
  • Right, left, channel, and total area of the subcatchment.
    
• Catwin.tab:  Window identification of the subcatchment areas defined in SBCT.TAB.
  • Node number corresponding to the subcatchment area window.
  • Minimum and maximum row/col value for the source, right, left, and channel subcatchment area.
    

Tabular output of program RASBIN:

• Netwb.tab:  Contains channel link information for the binary network.
  • Node index.
  • Strahler channel link order..
  • Channel link node code (source, junction or outlet).
  • Execution sequence of channel links for cascade type flow routing.
  • Next node downstream index number.
  • Terrain elevation.
  • Channel link length.
  • Upstream and direct drainage area.
  • Channel link slope.
    
• Sbctb.tab:    Contains subcatchment information for the binary network.
  • Subcatchment index.
  • Strahler order of the channel link the subcatchment drains into.
  • Right, left, and total area of the subcatchment.
    

Tabular output of program RASPRO:

• Elvcla.tab:    Minimum and mean of user defined elevation reclassification.
  • Class number.
  • Beginning elevation value of each class.
  • Mean elevation value of each class.

Tabular output of program PARAM:

• Sbcta.tab: Contains subcatchment area information for the raster network.
  • Subcatchment index.
  • Strahler order of the channel link the subcatchment drains into.
  • Right, left, channel and total area of the subcatchment.
  • Right, left and total area of the subcatchment with channel cells integrated.
    
• Sbctl.tab: Contains subcatchment length information for the raster network.
  • Subcatchment index.
  • Strahler oder of the channel link the subcatchment drains into.
  • Length to centroid from channel for source, right and left subcatchments.
  • Mean flow path length for source, right and left subcatchment areas.
    
• Sbcts.tab: Contains subcatchment slope information for the raster network.
  • Subcatchment index.
  • Strahler order of the channel link the subcatchment drains into.
  • Mean topograhpic slope of the source, right and left subcatchment area.
  • Mean flow path slope of the source, right and left subcatchment area.
  • Mean cell slope of the source, right and left subcatchment area.
    

top

Evaluation output files

General description
Evaluation output files contain statistics and derived data for channel and subcatchment properties. The files are are formatted ASCII files for user review. Headings and units are given in the files. The following is a listing and short description of evaluation output files.

List of files and evaluated parameters

• Netwt.evl:    Evaluation of the raster and binary channels and channel link data.
  • General network information
  • Number of channels and channel links.
  • Length of channels and channel links.
  • Elevation of channels and channel links.
  • Slope of channels and channel links.
  • Length weighted slope of channels and channel links.
  • Direct and total drainage areas.
  • Drainage density.
  • Channel link sinuosity.
  • Simplified drainage network coposition.
    
• Sbctt.evl:      Evaluation of the raster and binary subcatchment property data.
  • General information.
  • Subcatchment drainage areas.
  • Channel drainage areas.
  • Right drainage areas.
  • Left drainage areas.
  • Source drainage areas.

• Distribution of an executable version of TOPAZ
  (Proposed December 1998; implemented July 1999)

  A number of users have requested an executable version of TOPAZ that does not require compilation. This will be implemented for WINDOWS 95/98 using the Salford FTN95 compiler.

   The expected target date for final implementation and release is July 1999.

• Calculation of the distribution of slope-aspect pairs within a subcatchment
  (Proposed October 1998)

   The terrain aspect within a subcatchment may have a range of values depending on the level of terrain dissection by channels within the subcatchment. A single aspect value for the entire subcatchment is representative because aspect values in opposite direction cancel one another. The distribution of the aspect within the subcatchment provides a better picture of the aspect values associated with the subcatchment. Therefore, it is planned to implement the calculations of the aspect distribution in eight directions, including the average slope associated with each aspect direction.

   The expected target date for final implementation and release of calculations for slope-aspect distribution in September 1999.

• Calculation of representative subcatchment properties
  (Proposed in November 1997; implemented July 1999)

   Many subcatchment properties, such as slope and length, are distributed in nature which precludes the direct measurement of a single and unique. Since these properties vary through the subcatchment, they must be calculated based on a model that reduces the distributed values of the property into a representative value for the subcatchment. Alternative models to calculate representative subcatchment values for the area, slope and length are being considered for implementation into TOPAZ.

   The expected target date for final implementation and release of the calculations for representative subcatchment properties is May 1999.

Dr. Jurgen Garbrecht  USDA, Agricultural Research Service

Prof. Lawrence Martz  University of Saskatchewan

Dr. Jurgen Garbrecht
Research Hydraulic Engineer

Tel. : (405) 262 - 5291

Fax : (405) 262 - 0133

e-mail: garbrech@grl.ars.usda.gov

Mailing address:

USDA, Agricultural Research Service

Grazinglands Research Laboratory

7207 West Cheyenne Str.

El Reno, Oklahoma 73036

 

Degree :

• Dipl. Ing. ETHZ, Swiss Federal Institute of Technology, Zurich, Switzerland, 1977
• M.Sc. in Civil Engineering, Colorado State University, 1981
• Ph.D. in Civil Engineering, Colorado State University, 1984

Research:

• Climate variability and impacts on agricultural production
• Numerical analysis and characterization of topography from Digital Elevation Models
• Hydrologic system response to global change
• Modeling of soil water dynamics

Relevant Publications:

Garbrecht, J. and L. W. Martz. 1997. Automated Channel Ordering and Node Indexing for Raster Channel Networks. Computers & Geosciences, 23(9): 961-966.

Garbrecht, J. and L. W. Martz. 1997. The Assignment of Drainage Direction over Flat Surfaces in Raster Digital Elevation Models. Journal of Hydrology, 193:204-213.

Garbrecht J., P. J. Starks and L. W. Martz. 1996. New Digital Landscape Parameterization Methodologies. In: Proceedings of the 32nd Annual Conference and Symposium on GIS and Water Resources, American Water Resources Association, Herndon, Virginia, TPS-96-3, 482 p., pp. 357-365, September 22-26, 1996, Fort Lauderdale, Florida.

Garbrecht J., L. W. Martz and D. C. Goodrich. 1996. Subcatchment Parameterization for Surface Runoff Modeling using Digital Elevation Models. In: Proceedings of the American Society of Civil Engineers Hydraulics Conference, North American Water and Environment Congress '96, CD-ROM publication: Session C-126, "GIS Distributed Models: Data, Parameterization and Scale", 6 pages, Anaheim, California, June 1996.

Garbrecht J. and L. W. Martz. 1996. Digital Landscape Parameterization for Hydrologic Applications. In: Proceedings of HydroGIS '96, International Conference on Application of Geographic Information Systems in Hydrology and Water Resources Management, Vienna, Austria, IAHS Publication No. 235, pp. 169-173, April 1996.

Garbrecht, J. and P. J. Starks. 1995. Notes on the Use of USGS Level 1 7.5-Minute DEM Coverages for Landscape Drainage Analysis. Photogrammetric Engineering and Remote Sensing, 61(5):519-522, May 1995.

Garbrecht, J. and Martz, L.W. 1995. Advances in Automated Landscape Analysis. Proceedings of the First International Conference on Water Resources Engineering, American Society of Civil Engineers, San Antonio, 844-848.

Garbrecht, J., J. G. Arnold, and M. S. Seyfried. 1994. Watershed Characterization and Fractals. In: C. W. Richardson, A. Rango, L. B. Owens, and L. J. Lane (eds.), Proceedings of the ARS Conference on Hydrology, Denver, Colorado. U.S. Department of Agriculture, Agricultural Research Service, Publication No. 1994-5, 180 pp., pp. 81-100, September 1993.

Garbrecht, J., and L. W. Martz. 1994. Grid Size Dependency of Parameters Extracted from Digital Elevation Models. Computers and Geosciences, 20(1):85-87, 1994.

Garbrecht, J., and L. W. Martz. 1993. Network and Subwatershed Parameters Extracted From Digital Elevation Models: The Bills Creek Experience. Water Resources Bulletin, American Water Resources Association, 29(6):909-916, December 1993.

Garbrecht, J., and W. H. Shen. 1988. The Physical Framework of the Dependence between Channel Flow Hydrograph and Drainage Network Morphometry. Hydrologic Processes, John Wiley & Sons Ltd., 2(4):337-355, Oct-Dec 1988.

Garbrecht, J. 1988. Determination of the Execution Sequence of Channels in a Drainage Network for Cascade Routing. Hydrosoft, Software for Hydraulics, Hydrology and Hydrodynamics, Computational Mechanics Publications, 1(3):129-139, July 1988.

---

Lawrence W. Martz
Professor of Geography

Tel. : (306) 966- 5667

Fax : (405) 966- 5680

e-mail: martz@sask.usask.ca

Mailing address:

Department of Geography

9 Campus Drive

University of Saskatchewan

Saskatoon, Saskatchewan, S7N 5A5