dur.events: Calculates the duration of the median (or other percentile)...

In VulnToolkit: Analysis of Tidal Datasets

Description

Calculates the duration of the median (or other percentile) flooding event

Usage

dur.events(level, elevation, percentile = 0.5, units = "1 observation")

Arguments

level	a numeric vector of water levels or tide data
elevation	elevation(s) of interest (e.g., marsh platform, MHW). A vector of elevations is accepted. Elevation should be in the same vertical datum as level
percentile	the percentile(s) to find (median flooding event is used by default)
units	the time interval between measurements. This argument enables conversion of flooding durations to hours. units must be a string of the form XX units, where XX is an integer and units can be second, minute, hour, or their plurals. When time units are specified, all time units are converted to hours in output. When units are not specified, the output reports the number of sequential observations

Details

The duration of individual flooding events is calculated from water level data. dur.events() differs from fld.dur() in that the former examines individual flooding events, rather than cumulative inundation times.

Value

the duration of the median (or other percentile) flooding event occurring at a given elevation. If percentile is of length one, the value(s) returned are the corresponding flooding duration percentiles for the elevation(s) of interest. To ensure clarity when more than one percentile is sought, in those cases a dataframe is output to report elevations and flooding durations

Examples

data(NL_6min_2013)
MHW <- 0.9117  # New London MHW in 2013: 0.9117 m relative to MLLW

# median flooding duration at three elevations
dur.events(NL_6min_2013[, 2], elevation = c(0.5, MHW, 1.5), units = "6 minutes")

# a dataframe is output when results are more complex
dur.events(NL_6min_2013[, 2], elevation = MHW, 
           percentile = c(0.1, 0.5, 0.9), units = "6 minutes")
dur.events(NL_6min_2013[, 2], elevation = c(0.5, MHW, 1.5), 
  percentile = c(0.1, 0.5, 0.9), units = "6 minutes")

# dur.events() differs from fld.dur() in that it examines individual
# flooding events, rather than cumulative inundation

# The median flooding event at MHW lasts 2.9 hrs
dur.events(NL_6min_2013[, 2], elevation = MHW, units = "6 minutes")

# And over an entire year, MHW was flooded 13% of the time
fld.dur(z = MHW, NL_6min_2013[, 2])

VulnToolkit documentation built on Aug. 2, 2021, 5:07 p.m.