Calculate quantile from fitted log-Pearson type III distribution
Calculate the specified flow quantile from a fitted log-Pearson type III distribution from a time series of n-day low flows.
POR_calc_lp3_quantile(annual_min, p)
annual_min: 'numeric' vector. Vector of minimum annual n-day mean flows.p: 'numeric' value of exceedance probabilities. Quantile of fitted distribution that is returned (p=0.1 for 10-year return period, p=0.5 for 2-year return period)Specified quantile from the fitted log-Pearson type 3 distribution.
POR_calc_lp3_quantile fits an log-Pearson type III distribution to a series of annual n-day flows and returns the quantile of a user-specified probability using calc_qlpearsonIII. This represents a theoretical return period for than n-day flow.
POR_calc_lp3_quantile(annual_min = example_annual$low_q1, p = 0.1)
Asquith, W.H., Kiang, J.E., and Cohn, T.A., 2017, Application of at-site peak-streamflow frequency analyses for very low annual exceedance probabilities: U.S. Geological Survey Scientific Investigation Report 2017–5038, 93 p. [Also available at https://doi.org/10.3133/sir20175038.]
calc_qlpearsonIII