eflowcalc.th2

eflowcalc.th2(flows, datetimes, hydro_years, drainage_area)

Variability in timing of annual maximum flow.

Calculation Details

Determine the day of the year (i.e. number) in the Julian calendar where the flow is maximal in each hydrological year in the daily flow record. Map these dates onto a circular scale as angles in radians. Determine the x and y components of these angles (i.e. cosine, and sine, respectively). Compute the mean of the x and y components separately. Compute the variability using the following equation:

√(2 * (1 - √(X*X + Y*Y))

where √ is the square root, and X and Y are the mean of the x and y components of the angles, respectively.

Convert this angular variability back to a day of the year in the Julian calendar.