FlowScreen (version 2.1)

screen.metric: Plot a metric with trend and change points

Description

This function plots a time series of a streamflow metric with the prewhitened linear trend and any detected changepoints in mean and variance.

Usage

screen.metric(y, ylabel = "", title = FALSE, change.margins = TRUE)

Value

Returns a list containing results from the trend and changepoint analysis. This list has the following elements:

• slope - Numeric vector containing the intercept and slope of the prewhitened linear trend computed with zyp.trend.vector using Yue Pilon's method

• ci1 - numeric vector containing the intercept and slope of the upper confidence bound. See confint.zyp

• ci2 - numeric vector of length 2 containing the intercept and slope of the lower confidence bound. See confint.zyp

• pval - numeric value indicatng the significance value of the detected trend, Kendall test computed within zyp.trend.vector

• cpts - numeric vector of changepoints if any are found, computed with cpt.meanvar. Will be NULL if changepoint analysis was not run due to insufficient data.

• means - numeric vector of means computed with cpt.meanvar. Will be NULL if changepoint analysis was not run due to insufficient data.

Arguments

y

Numeric vector with "times" attribute, and, optionally, a 'StationID' and a 'Agency' attribute if you want the function to auto-generate a default plot title.

ylabel

Character string for the y-axis label

title

optional plot title. Default is FALSE indicating no plot title is wanted. Set to TRUE to use the the default plot title, which will look for 'plot title' attribute of the data.frame set by set.plot.titles. All values other values will be used as a custom plot title. Set to FALSE to use this function in a multi-plot layout.

change.margins

TRUE or FALSE to indicate whether the user's current margin settings should be used, or if the margins should be set within the function. Default is TRUE, to set margins to the minimal amount.

Author

Jennifer Dierauer

Details

This function plots detected changepoints as a vertical dashed line. The means on either side of a changepoint are plotted as solid black lines. If the temporal trend is significant (p-value < 0.1), the trend is plotted as a blue or red line for an increasing or decreasing trend, respectively. The upper and lower 95 dotted red or blue lines. If a trend is not significant, it is not plotted.

See Also

See screen.summary to create a summary screening plot of high flow, low flow, or baseflow metrics.

See metrics.all to calculate 30 different streamflow metrics at once. The screen.metric function could then be used to loop through the metrics and create an individual plot for each.

Examples

data(cania.sub.ts)

# calculate and plot the annual maximum series
cania.sub.ts <- set.plot.titles(cania.sub.ts)
res <- pk.max(cania.sub.ts)
res1 <- screen.metric(res, ylabel=cania.sub.ts$FlowUnit[1], 
title = TRUE)

# calculate and plot the annual minimum series
res <- MAMn(cania.sub.ts, n=1)
res1 <- screen.metric(res, ylabel="Discharge (m3/s)", 
title = TRUE)