Calculates various metrics that describe the distribution of a time series of streamflow
Calculates various metrics that describe the distribution of a time series of streamflow, which can be of any time step.
POR_distribution_metrics(value, quantile_type = 8, na.rm = TRUE)
value: 'numeric' vector of values (assumed to be streamflow) at any time step.
quantile_type: 'numeric' value. The distribution type used in the stats::quantile
function. Default is 8 (median-unbiased regardless of distribution). Other types common in hydrology are 6 (Weibull) or 9 (unbiased for normal distributions).
na.rm: 'boolean' TRUE or FALSE. Should NA values be removed before computing. If NA values are present and na.rm = FALSE, then function will return NAs. Default is TRUE.
A data.frame with FDC quantiles, and distribution metrics. See Details . This function calculates various metrics that describe the distribution of a time series of streamflow, which can be of any time step.
Metrics computed include:
p_n: Flow-duration curve (FDC) percentile where n = 1, 5, 10, 25, 50, 75, 90, 95, and 99POR_mean: Period of record meanPOR_sd: Period of record standard deviationPOR_cv: Period of record coefficient of variationPOR_min: Period of record minimumPOR_max: Period of record maximumLCV: L-moment coefficient of variationLskew: L-moment skewnessLkurtosis: L-moment kurtosisPOR_distribution_metrics(value = example_obs$streamflow_cfs)
Farmer, W.H., Archfield, S.A., Over, T.M., Hay, L.E., LaFontaine, J.H., and Kiang, J.E., 2014, A comparison of methods to predict historical daily streamflow time series in the southeastern United States: U.S. Geological Survey Scientific Investigations Report 2014–5231, 34 p. [Also available at https://doi.org/10.3133/sir20145231.]
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.]
Asquith, W.H., 2021, lmomco---L-moments, censored L-moments, trimmed L-moments,
L-comoments, and many distributions. R package version 2.3.7, Texas Tech University, Lubbock, Texas.
lmoms, quantile