Assessing the Influence of Zero-Flow Threshold Choice for Characterising Intermittent Stream Hydrology

Zero-flow recordings in gauged streamflow data are critically important for intermittent stream research. Acknowledging the high uncertainty in zero-flow recordings, many studies pick a small number as zero-flow threshold, below which the flow is considered to be zero. The choice of zero-flow threshold is often arbitrary or unjustified, which leads us to wonder: would selecting a slightly different threshold change analysis result significantly? Here, we used a simple sensitivity analysis to assess how the choice of zero-flow threshold impacts the calculated values of relevant metrics to intermittent stream research. Results show that these metrics tended to be more sensitive to lower zero-flow thresholds, suggesting that even choosing a slightly different threshold could lead to meaningfully different results from the management perspective. This study highlights the need for reasonable justification of the choice of zero-flow threshold and concludes with potential ways to reduce uncertainty in zero-flow measurement.