Precision and accuracy of streamflow measurements in headwater streams during baseflow

Precisão e acurácia de medições de vazão em rios de cabeceira durante o escoamento de base

ABSTRACT

The quantification of baseflow is key for water resources management. However, there are few reports on the precision and accuracy in low streamflow measurements. In this paper, we systematically analyze the precision and accuracy of dilution streamflow measurements in headwater channels during baseflow. Precision refers to the variability of the values for repeated measurements and accuracy is how much the measured value approximates the reference one. We measured streamflow in 31 different cross-sections with contributing areas ranging from 0.02 to 5.33 km². Streamflow measurements with the current meter were adopted as reference for accuracy estimation. A precision error of ±5.0% was found for the measurements. The percent errors compared to reference streamflow ranged from 0.7 to 45.6%, with a median of 6.1%. Precision and accuracy are in the same order of magnitude found in the literature for larger streams. These results can be used for constraining the uncertainty of streamflow measurements and rainfall-runoff modeling of headwater streams.

Keywords:
Hydrometry; Dilution method; Baseflow; Headwater streams