The development and assessment of a regionalised daily rainfall disaggregation model for South Africa

Abstract

The temporal distribution of rainfall, viz. the distribution of rainfall intensity during a storm, is an important factor affecting the timing and magnitude of peak flow from a catchment and hence the flood-generating potential of rainfall events. Rainfall intensity is also one of the primary inputs into hydrological models used for the design of hydraulic structures. In the absence of continuously recorded rainfall data, one method of estimating the temporal distribution of rainfall is to disaggregate coarser-scale data into a finer resolution, e.g. from daily data into hourly rainfall information. In this study, a daily to hourly disaggregation model developed in Australia, and modified for application in South Africa, is used. However, this model requires input obtained from short-duration data at the desired location. Owing to the paucity of short-duration data in South Africa, the methodology is regionalised to enable the application of the model at a national scale, particularly at locations where only daily data are available.

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