ABSTRACT Most applied hydrologists and investigators appear to bypass any serious consideration of the uncertainty in published daily discharges. This paper offers a relatively simple and easy to understand procedure to estimate relative uncertainty in daily discharges using stream gaugings and rating curve(s) from which the published daily discharges were computed. Uncertainty is assessed through two metrics: the root mean square error of the difference between gauged and rating curve discharges expressed as a ratio of the mean gauged daily discharge; and the percentage flow volume extrapolated above the maximum rated discharge. The first metric can be calculated separately for low and high discharges. These metrics have been computed for 459 gauging stations drawn from Australia’s high quality Hydrologic Reference Stations (HRS) (http://www.bom.gov.au/water/hrs/index.shtml). The two metrics can be computed by investigators which allow them to assess uncertainty in their daily discharge data against the metrics derived for the high-quality dataset.
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