EVALUATION OF SPATSIM AS A METHOD OF APPLYING THE

MODEL AND STORING DATA

SPATSIM is a generic software package designed as a database, data analysis and modelling system, specifically for hydrological and water resource applications (Hughes, 2002). It has been developed using the Delphi programming language with links to Paradox database tables and uses ESRI Map Objects to provide the spatial data display and analysis facilities. (Refer to detailed description of SPATSIM in section 4.2).

The facilities that are included within SPATSIM to enable data to be stored, displayed and processed can be divided up into internal facilities that are not specific to any

application and external processes that include a wide range of hydrological, water resource and eco-hydrological models some of which are listed in the screen display in Figure 8.3. It is designed to be as user-friendly as possible with help facilities accessible within the software, or via the ‘Hydrological Software’ link on the Institute for Water Research web site (http://www.ru.ac.za/iwr/software/spatsim.html).

Figure 8.3: SPATSIM and some of the linked external processes

The SPATSIM package was developed with the needs of hydrological and water resource models in mind, and therefore it is designed to provide all the basic facilities needed (from data preparation to calibration process) to undertake model calibrations. In the assessment of the software as a method of applying the model and storing data, the successful calibration process for the Kafue River basin can be given as an example in that the whole process of Pitman calibration presented in this report was achieved with little use of other programs, the majority of the requirements being met by SPATSIM itself. One area where external programs are required is in the presentation of time series results. The output options from SPATSIM (specifically the graphics outputs from TSOFT) are somewhat limited and do not usually provide

‘report quality’ graphics. However, it is a relatively simple process to export the data and use the graphics capabilities of a spreadsheet program to produce the required diagrams (for example, Figure 8.1). While the GIS capabilities of SPATSIM are relatively limited, the rendering facility is very useful for displaying the geographic distribution of parameter values or summary indices of hydrology or climate (see Figure 8.2 for example). As SPATSIM makes use of shape files for the spatial data, it is a relatively simple matter to use one of several commercial GIS packages for any additional spatial analyses, or spatial data manipulations, that are required.

Since the software has been developed by a research and teaching organisation (Institute for Water Research), it is being continuously developed and upgraded in order to be responsive to the needs of the user group (now represented by some 30 individuals and groups within southern Africa, as well as a few in other parts of the world). In the last two years (2002 – 2004) the software has been upgraded from version 2.0.0.0 to 2.0.0.6.

With respect to its evaluation for use in the type of study referred to here, it should be further emphasized that it is not designed to apply only one model, but any of several models. This means that some of the user actions required are slightly more complicated than if the system was designed for a single purpose. This implies that the learning and familiarisation process is also somewhat longer. However, the advantages of being able to apply several linked models within the same data management environment should outweigh the disadvantages of spending more time learning how to use the package.

In general terms, many of the hydrology and water resource models that are available within the southern African region have been based on DOS operating systems that access their data from, and write results to text files. This implies that many users of hydrological models are less than familiar with the concepts of storing information in database tables. This can cause confusion for first time users of the SPATSIM system and takes some time to get used to. This is, however, a problem that is soon overcome as users become familiar with the package. The use of database tables certainly makes managing the large amounts of data associated with a modelling study of this type much more efficient in the long-term.

The concepts of referencing data through the SPATSIM ‘attributes’ and managing these, can also be somewhat difficult to learn at first. It is important to manage the names of these attributes properly, otherwise the user can become confused and easily forget where specific data are stored. It would be an advantage to have some kind of internal text ‘dictionary’ that could include user-entered explanations of what each attribute is and what type of data are stored. This is especially relevant if there are long gaps between using a specific application of SPATSIM.

The graphical display and time series comparison capabilities of TSOFT are particularly useful in the context of calibrating a rainfall-runoff model. The ability to visually examine, and statistically compare, a number of sets of results as parameters are changed is a great help in any manual calibration process. The methods available for summarising time series, such as flow duration curves and seasonal distributions are also very helpful.