calc_frequencyHigh: Indices describing frequency of high flow events.

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

Indices describing frequency of high flow events.

Description

Calculates 11 indices used to describe the frequency of high flow conditions. See Table X in the EflowStats package vignette for a full description of indices.

Usage

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

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.
floodThreshold	Numeric flood threshold as the flow equivalent for a flood recurrence of 1.67 years
...	Optional arguments needed for calc_allHIT function

Details

Descriptions of indices.

• fh1 High flood pulse count. Compute the average number of flow events with flows above a threshold equal to the 75th percentile value for the entire flow record. FH1 is the average (or median-Use Preference option) number of events.

• fh2 Variability in high pulse count. Compute the standard deviation in the annual pulse counts for FH1. FH2 is 100 times the standard deviation divided by the mean pulse count (number of events/year-spatial).

• fh3 High flood pulse count. Compute the average number of days per year that the flow is above a threshold equal to three times the median flow for the entire record. FH3 is the mean (or median-Use Preference option) of the annual number of days for all years.

• fh4 High flood pulse count. Compute the average number of days per year that the flow is above a threshold equal to seven times the median flow for the entire record. FH4 is the mean (or median - Use Preference option) of the annual number of days for all years.

• fh5 Flood frequency. Compute the average number of flow events with flows above a threshold equal to the median flow value for the entire flow record. FH5 is the average (or median - Use Preference option) number of events.

• fh6 Flood frequency. Compute the average number of flow events with flows above a threshold equal to three times the median flow value for the entire flow record. FH6 is the average (or median-Use Preference option) number of events.

• fh7 Flood frequency. Compute the average number of flow events with flows above a threshold equal to seven times the median flow value for the entire flow record. FH7 is the average (or median-Use Preference option) number of events.

• fh8 Flood frequency. Compute the average number of flow events with flows above a threshold equal to 25-percent exceedence value for the entire flow record. FH8 is the average (or median-Use Preference option) number of events.

• fh9 Flood frequency. Compute the average number of flow events with flows above a threshold equal to 75-percent exceedence value for the entire flow record. FH9 is the average (or median-Use Preference option) number of events.

• fh10 Flood frequency. Compute the average number of flow events with flows above a threshold equal to median of the annual minima for the entire flow record. FH10 is the average (or median-Use Preference option) number of events.

• fh11 Flood frequency. Compute the average number of flow events with flows above a threshold equal to flow corresponding to a 1.67-year recurrence interval. FH11 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"
floodThreshold = 1158
calc_frequencyHigh(x=x,yearType=yearType,floodThreshold = 1158)

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