Abstract:
Large errors in estimates of peak discharge in medium to large catchments in
South Africa can be largely ascribed to significant errors in the estimation of the
catchment response time, mainly as a consequence of the use of inappropriate
time variables, the inadequate use of a simplified convolution process between
rainfall–run-off time variables, and the lack of locally developed empirical
methods to estimate catchment response time parameters. Furthermore, the use
of a typical convolution process between a single hyetograph and hydrograph to
estimate observed time parameters at large catchment scales is regarded as not
practical, as such simplification is not applicable in real, large heterogeneous
catchments where antecedent moisture from previous rainfall events and spatially
non-uniform rainfall hyetographs can result in multipeaked hydrographs.
This paper presents the development and evaluation of an alternative, improved
and consistent approach to estimate catchment response time expressed as the
time to peak (TP) in the C5 secondary drainage region in South Africa, while the
interrelationship, similarity and proportionality ratios between TP and the conceptual
time of concentration (TC) and lag time (TL) are also investigated.
