Calculate the group 4 IHA parameters.

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Description

The group 4 IHA parameters measure the frequency and duration of high and low pulses.

Usage

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  group4(x, year = c("water", "calendar"),
    thresholds = NULL)

Arguments

thresholds

vector of length 2; the cut off for a low pulse and a high pulse, respectively

x

A zoo object containing the flow series

year

the type of year factor to be used, yr = 'water' or yr = 'calendar' for water years and calendar years respectively

Details

By default, the pulse thresholds are the 25th and 75th percentiles of the distribution of flows. TNC's IHA software uses the quantile as defined http://www.roguewave.com/portals/0/products/imsl-numerical-libraries/c-library/docs/8.0/html/cstat/stat.htm which corresponds to R's type = 6 option in quantile. The default thresholds here are calculated using R's default type = 7 option.

Value

a matrix of group 3 parameters

Author(s)

jason.e.law@gmail.com

References

http://www.conservationgateway.org/Files/Pages/indicators-hydrologic-altaspx47.aspx

Examples

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