Low/High Flow Categorization #17
Description
In the default definition of low and high flows in sig_x_Q_frequency.m and sig_x_Q_duration.m, there is a case where periods can be defined as high and low flows simultaneously.
As low flows are defined based on the mean (0.2 * mean(Q)) and high flows on the median (9 * median(Q)), there could be issues, e.g., in basins with intermittent flow where the median can be 0 (or very close to 0). Following the definition, any flow exceeding 0 (= 9 * median(Q)) would now be considered high flow, and any flow smaller than 0.2 * mean(Q) would also be considered low flow.
I have attached a CSV file containing roughly two years of streamflow data for an Australian catchment (143100A) from the Caravan dataset for which the issue can be reproduced. In the given example, roughly 20% of all timesteps are considered both low and high flow.
streamflow_camelsaus_143110A_example.csv
I think it would be helpful to flag these cases; it may be worth considering the mean for the high flow definition to resolve the issue.