Presenter/Author Information

J. P. Norton

Keywords

hydrology, uncertainty, model calibration, model performance measurement

Start Date

1-7-2010 12:00 AM

Description

The effective rainfall-flow module of a "top-down" hydrological model haslinear, fixed dynamics, giving a two-exponential instantaneous unit hydrograph (IUH)often interpreted as summing slow- and quick-flow components. Such components sufferuncertainty due to ignorance of rainfall variation between samples and ignorance of delayin the IUH. If they are obtained from linear-in-parameters models, ill conditioning in theconversion amplifies the uncertainty. The extent of these uncertainties is analysed, withexamples. The paper also considers alternatives to performance assessment of such modelsby Nash-Sutcliffe efficiency. Rather than employing the sample mean as an outputpredictionbenchmark, they use almost equally simple predictors taking the flow correlationstructure into account. Again numerical examples are given.

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Jul 1st, 12:00 AM

Limitations in Interpretable Top-Down Effective Rainfall-Runoff Modelling

The effective rainfall-flow module of a "top-down" hydrological model haslinear, fixed dynamics, giving a two-exponential instantaneous unit hydrograph (IUH)often interpreted as summing slow- and quick-flow components. Such components sufferuncertainty due to ignorance of rainfall variation between samples and ignorance of delayin the IUH. If they are obtained from linear-in-parameters models, ill conditioning in theconversion amplifies the uncertainty. The extent of these uncertainties is analysed, withexamples. The paper also considers alternatives to performance assessment of such modelsby Nash-Sutcliffe efficiency. Rather than employing the sample mean as an outputpredictionbenchmark, they use almost equally simple predictors taking the flow correlationstructure into account. Again numerical examples are given.