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TOPAZ (Topographic Parameterization) 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
applications.
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.
Some significant characteristics of TOPAZ
- TOPAZ generates raster output
files of the drainage network, subwatershed 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 layers and spatial analysis.
- TOPAZ also 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.
- TOPAZ effectively handles depressions and flat areas in the input DEM using an
innovative combination of depression
outlet breaching, depression-filling, and relief imposition.
- TOPAZ uses a method of assigning identification
codes to drainage features that is based on a network node numbering
system.
This node numbering system can be used to optimize hydraulic routing between subwatersheds
and to indicate the relation between channel junctions, channel links and subwatershed
contributing areas.
- One of the advantages that TOPAZ offers in hydrologic analysis and modeling, is the
capacity to delineate the channel network and segment the landscape into subwatersheds at
a varying level of detail.
This is accomplished by manipulating the user-controlled parameters of critical source
area (CSA) and minimum source channel length (MSCL).
More information:
- a detailed overview
of functionality, software design, hardware and data requirements, etc.
- to download a copy of the TOPAZ software
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Jurgen Garbrecht
