Continuous baseflow separation from time series of daily and monthly streamflow data

Abstract

Continuous baseflow separation procedures have been frequently used to differentiate total flows into the high-frequency, lowamplitude ‘baseflow’ component and the low-frequency, high-amplitude ‘flood’ flows. In the past, such procedures have normally been applied to streamflow time-series data with time steps of 1 day or less. However, there are applications in South Africa (notably related to setting instream flow requirements) where the only available data for natural flow conditions are monthly flow volumes. A relatively experienced hydrologist can be expected to successfully calibrate a separation model using daily data, coupled with a conceptual understanding of the hydrological processes prevailing in the catchment. The same cannot be said for monthly data, as the majority of the information on short-term flow variability has been lost. As part of a regional study covering the whole of South Africa, this paper presents some example results of comparisons between daily and monthly separations.

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