Three modelling approaches for seasonal streamflow droughts in southern Africa: the use of censored data |
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Authors: | EMMA L TATE STEPHEN N FREEMAN |
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Institution: | 1. Institute of Hydrology , Wallingford, Oxfordshire, OX10 8BB, UK E-mail: elt@ceh.ac.uk;2. British Trust for Ornithology , Thetford, Norfolk, IP24 2PU, UK E-mail: steve.freeman@bto.org |
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Abstract: | Abstract Three approaches to modelling the duration of streamflow droughts at eight southern African sites are considered; a non-parametric method (that of Kaplan-Meier) is compared with the fitting of two simple parametric models: the exponential and Weibull. All techniques allow the instantaneous probability of a drought coming to an end to differ between wet and dry seasons, using the concept of censored data. Model-fitting is discussed, and the Kaplan-Meier estimates permit an assessment of the fit of the parametric models, with the aim of finding a parsimonious model for the data, which can be used for predictive purposes. In most cases considered herein, either the exponential or Weibull approach is found to be adequate. |
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Keywords: | climate change impacts climate scenario analyrsis yield changes mathematical modelling forest hydrology hydrological processes South Dakota USA |
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