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Welcome!

Welcome to TOPOG Online. This web site has been developed to give users access to information on the TOPOG model. This model has been developed by a large group of scientists from CSIRO Land and Water and the Cooperative Research Centre for Catchment Hydrology. It has its genesis in the WETZONE program, developed by Dr Emmett O'Loughlin in the mid-1980's, but has undergone radical change since then. Development on TOPOG started in late 1987 and is still active. You can download the TOPOG source code and executables from this web site, but you must first apply to us for access. We encourage you to apply and test the model. Please let us know about any bugs you find, but tell us if the model performs well too! If you develop a new routine, or improve an old one, we would like to hear about it. With your approval, we might even make it available to the rest of the world though this web site.

What is TOPOG?

TOPOG is a terrain analysis-based hydrologic modelling package which can be used to:

describe the topographic attributes of complex three dimensional landscapes

predict the spatial distribution of steady state waterlogging, erosion hazard and landslide risk indices

simulate the transient hydrologic behaviour of catchments, and how this is affected by changing catchment vegetation

model the growth of vegetation and how this impacts on the water balance

model solute movement through the soil

model sediment movement over the soil surface

TOPOG describes how water moves through landscapes; over the land surface, into the soil, through the soil and groundwater and back to the atmosphere via evaporation. Conservative solute movement and sediment transport are also simulated.

The primary strength of TOPOG is that it is based on a sophisticated digital terrain analysis model, which accurately describes the topographic attributes of three-dimensional landscapes. It is intended for application to small catchments (up to 10 km², and generally smaller than 1 km²).

We refer to TOPOG as a "deterministic", "distributed-parameter" hydrologic modelling package. The term "deterministic" is used to emphasise the fact that the various water balance models within TOPOG use physical reasoning to explain how the hydrologic system behaves. The term "distributed-parameter" means that the model can account for spatial variability inherent in input parameters such as soil type, vegetation and climate.

What can TOPOG be used for?

TOPOG is relevant to a wide range of water and land management issues, including:

waterlogging and dryland salinity

catchment water yield

stormflow runoff production

soil erosion and deposition

trafficability assessment

land disposal of treated effluent

forest establishment and harvesting

landslide hazard assessment

ecologic habitat assessment

Having said this, it is important to appreciate that TOPOG is intended as a research tool. If you intend to attach significance to model results, please read our Disclaimer first.

Model Specifications

TOPOG consists of over 30 FORTRAN and C programs. Some of the programs are interactive, entailing the use of mouse-driven menus and high level graphics functions. The screen graphics routines and user interface are written in X-WINDOWS and MOTIF.

The full TOPOG package will only run on UNIX workstations. We recommend a workstation with the following specifications:

• at least 32 MB core memory, preferably 64 MB
• at least 100 MB free disk space, preferably 200 MB
• a high resolution colour graphics monitor, preferably 1280 x 1024 pixels, in a 19 inch format