The advantages of incorporating variable length time steps into deterministic hydrological models are discussed and a method based on the use of rainfall thresholds to determine appropriate length steps automatically is presented. The method has been incorporated into a continuous catchment hydrology simulation model that was developed from an earlier version of a single-event flood model. The model, data preparation, and results analysis and display functions are all contained within a more general model application software package (HYMAS -- Hydrological Modelling Application System), which is currently being developed. A brief description of the components of the model is provided, with emphasis on the effects on their operation using different length time steps of modelling. Data from a semi-arid grassland catchment in South Africa and an arid catchment in Arizona, USA, are used to illustrate that a variable time interval approach can improve the overall efficiency of a model.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.