Quantifying Uncertainty in Velocity-area Streamflow Measurements Under Non-ideal Conditions

The measurement of discharge by the velocity-area method is a commonly used technique but methods for estimating its quantitative uncertainty are rarely studied in non-ideal conditions. Three methods for estimating uncertainty – ISO 748, IVE, and FLAURE – were compared across cross-sections representing both near-ideal and non-ideal conditions along a small, regulated river on Vancouver Island, British Columbia. High-resolution measurements were collected using an acoustic doppler velocimeter with verticals spaced every 0.1 m. Measurements were sub-sampled to investigate the effect of sampling frequency on total uncertainty. All three methods compared well under near-ideal conditions but diverged for sites with non-ideal conditions. Increasing the number of verticals did not improve discharge accuracy for non-ideal conditions. The IVE method was deemed the most conservative and sensitive estimate of total uncertainty in non-ideal conditions when the number of verticals was greater than 20. Further research is required to test how other sampling strategies may improve discharge accuracy for non-ideal conditions, such as increasing the number of velocity measurements at each vertical. Keywords: streamflow, hydrometrics, velocity-area method, flowtracker2, discharge, uncertainty, IVE, FLAURE, ISO

Author dc:creator

• Jeffery, Jonathan

Advisor dc:contributor.advisor

• Moore, Dan

• School of environment and sustainability

Language dc:language.iso

en_US

Identifier URI

https://doi.org/10.25316/IR-20986

OAI identifier oai:identifier

oai:null:10613/29459