eflowcalc.ta1

eflowcalc.ta1(flows, datetimes, hydro_years, drainage_area)

Constancy by Colwell (1974) applied to flows.

Calculation Details

Compute the decimal logarithm of the daily flow values. Calculate the decimal logarithm of the overall mean daily flow for the entire record. Compute the Colwell matrix featuring 365 rows for 365 d in a year (ignoring last day of February for leap years) and 11 columns for 11 flow states (break points are 0.10, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, and 2.25 times the log mean daily flow calculated previously) for each hydrological year, incrementally adding to the tally in each cell from year to year.

Calculate Y, the sum of each column (vector), and Z, the sum of the whole matrix (scalar). Divide the elements of vector Y by scalar Z. Multiply the elements of the new vector by their respective decimal log-transformed value; sum the elements of the vector to obtain a scalar; and multiply by minus one to obtain the uncertainty with respect to state H(Y). Divide H(Y) by the decimal log of the number of states (11), and subtract this ratio from one.