FlowScreen (version 2.0)

pk.cov: Center of Volume

Description

This function calculates center of volume metrics, including the day of the hydrologic year that 25 percent, 50 percent, and 75 percent of the total annual streamflow is reached. A value of 0 is returned for years with no flow. Hydrologic years with fewer than normal observations (outliers) are excluded from the analysis, and for stations with seasonal flow records, additional seasonal subsetting is done to include only days with observations in all years.

Usage

pk.cov(TS, threshold.missing = 0.5)

Value

Returns a data.frame with the following columns:

• hYear - Hydrologic Years

• Q25 - day of hydrologic year for 25 percent of the total annual streamflow

• Q50 - day of hydrologic year for 50 percent of the total annual streamflow, i.e. Center of Volume

• Q75 - day of hydrologic year for 75 percent of the total annual streamflow

• Dur - duration of between the 25 percent and 75 percent day of year, in days

Arguments

TS

data.frame of streamflow time series loaded with read.flows.

threshold.missing

Numeric value indicating the fraction of data that can be missing in a single year. Years with a missing data above this threshold will have NA values returned. Default is 0.5 (max of 50% missing data allowed).

Author

Jennifer Dierauer

Examples

data(cania.sub.ts)
cania.sub.ts <- set.plot.titles(cania.sub.ts, 
title.elements = c("StationID", "StnName", "StateProv"))
res1 <- pk.cov(cania.sub.ts)

# trend and changepoint plot for baseflow peak start doy
res2 <- screen.metric(res1[,2], "Day of Year")
res2 <- screen.metric(res1[,2], "Day of Year", title = TRUE)