calc_frequencyLow: Indices describing frequency of low flow events.

In USGS-R/EflowStats: Hydrologic Indicator and Alteration Stats

Indices describing frequency of low flow events.

Description

Calculates 3 indices used to describe the frequency of low flow conditions. See Table X in the EflowStats package vignette for a full description of indices.

Usage

calc_frequencyLow(
  x,
  yearType = "water",
  wyMonth = 10L,
  digits = 3,
  pref = "mean",
  ...
)

Arguments

x	A dataframe containing a vector of date values in the first column and vector of numeric flow values in the second column.
yearType	A character of either "water" or "calendar" indicating whether to use water years or calendar years, respectively.
wyMonth	A numeric. The month of the year in which the water year starts (1=January, 12=December). The water year begins on the first day of wyMonth.
digits	A numeric. Number of digits to round indice values
pref	A character of either "mean" or "median", indicating whether to use mean or median. See details.
...	Optional arguments needed for calc_allHIT function

Details

Descriptions of indices.

• FL1; Low flood pulse count. Compute the average number of flow events with flows below a threshold equal to the 25th percentile value for the entire flow record. FL1 is the average (or median-Use Preference option) number of events.

• FL2; Variability in low pulse count. Compute the standard deviation in the annual pulse counts for FL1. FL2 is 100 times the standard deviation divided by the mean pulse count.

• FL3; Frequency of low pulse spells. Compute the average number of flow events with flows below a threshold equal to 5 percent of the mean flow value for the entire flow record. FL3 is the average (or median-Use Preference option) number of events.

Value

A data.frame of flow statistics

Examples

x <- sampleData[c("date","discharge")]
yearType = "water"
calc_frequencyLow(x=x,yearType=yearType)

USGS-R/EflowStats documentation built on Sept. 30, 2023, 9:31 p.m.