Temporal distribution of storm rainfall on the Witwatersrand and its effect on peak flows.

[摘要] The temporal distribution of rainfall can have asignificant effect on peak runoff, especially so in thesmall catchments that are typical of the Witwatersrand.This report investigates the shape of the naturalhyetoraph and its use in the analysis of peak runoff.It describes the climatology of the sub-continent andrain-producing systems. Then more specifically,aspects of rainfall over Johannesburg are discussed.Some Of the more commonly-used temporal distributionsof rainfall are reviewed and the relationship betweenintensity-time distributions and mass curves isillustrated.Mass curves are derived using data from a rain gauge in Norwood, Johannesburg. The data is analysed with theassistance of a computer program and classified intoquartiles. The quartiles are further analysed in anattempt to define their characteristics in greaterdetail.The mass curves are used wIth a hydrological model togenerate hydrographs. The values of runoff peaks arefound to be comparable with those obtained usingcurrently accepted temporal rainfall distributions.

[发布机构] University of the Witwatersrand