Download the TOPMODEL demonstration software click here

Download the TOPMODEL example project click here

This program is intended as a demonstration version of TOPMODEL for Windows and has been developed from versions used for teaching purposes over a number of years in the Environmental Science degree course at Lancaster University. Since 1974 there have been many variants of TOPMODEL developed at Leeds, Lancaster and elsewhere but never a "definitive" version. This has been quite intentional. TOPMODEL is not intended to be a traditional model package but is more a collection of concepts that can be used where appropriate. It is up to the user to verify that the assumptions made are appropriate (see the discussion of limitations in Beven et al., 1995 and Beven, 1997). This version of this program will be best suited to catchments with shallow soils and moderate topography which do not suffer from excessively long dry periods. Ideally, predicted contributing areas should be checked against what actually happens in the catchment (at least qualitatively).

The model supplied here has deliberately not been provided with an automatic optimisation routine. This is for two reasons:

Firstly, the user is encouraged to view the output from the model and think about how the model is working. This is made possible, in part, by the fact that the results can be mapped back into space and viewed by the user in their correct spatial context. In this way, it may be concluded that this is not a good model to represent a particular catchment (but by thinking about why, it may be possible to improve the representation in some relatively simple way). This is why the distributed nature of the model predictions, combined with a simplicity of structure, is very important. Use it firstly as an aid to understanding before it is used as a predictive tool.

Secondly, we do not believe that there is an optimum set of parameter values, even with a model that is as parametrically parsimonious as TOPMODEL and do not want to encourage the practice of automatic optimisation. At Lancaster we are now using the GLUE methodology (see Chapter 7) to carry out calibration/sensitivity analysis/uncertainty estimation based on many thousands of runs. This version of TOPMODEL provides an option for output of Monte Carlo simulation results for later use with the compatible GLUE package.

Each catchment application requires a PROJECT FILE. This file has only four lines as follows:

1. Text description of application
2. Catchment Data filename
3. Hydrological Input Data filename
4. Topographic Index Map filename (may be left blank, but line must exist).

An example Project file and associated data files are also provided. The map of the topographic index may be prepared from a raster digital elevation file using the DTM-ANALYSIS program.

There are three options available in the program as follows:

The Hydrograph Prediction Option

This option allows the model to be run and hydrographs displayed. Parameter values can be changed on screen and the model run again. After each run several indices of goodness of fit are given for evaluation.

If not all the time period of the simulation can be displayed at one time, the hydrograph can be scanned backwards and forwards using the arrow buttons.

If a Topographic Index Map File is available then a map button is displayed that allows the display of predicted simulation, either as a summary over all time steps or animated.

The Sensitivity Analysis Option

This screen allows the sensitivity of the objective functions to changes of one or more of the parameters to be explored. An initial run of the model is made with the current values of the parameters. Then each chosen parameter is varied across its range, keeping the values of the other parameters constant. The results are displayed as small graphs. Any of the current parameter values or minimum and maximum of the range to be included can be changed on screen.

The Monte Carlo Analysis Option

In this option a large number of runs of the model can be made (limited only by storage capacity of the results file!!) using uniform random samples of the parameters chosen for inclusion in the analysis. Values of the other parameters are kept constant at their current values. Check boxes can be used to choose the variables and objective functions to be saved for each run.

The results file produced will be compatible with the GLUE analysis software package.