Plot annual high and low flows

Plots annual n-day minimum and maximum values and the day of year of occurrence of daily flow values from a daily streamflow data set. Calculates statistics from all values, unless specified. Returns a tibble with statistics.

plot_annual_extremes(
  data,
  dates = Date,
  values = Value,
  groups = STATION_NUMBER,
  station_number,
  roll_days = 1,
  roll_days_min = NA,
  roll_days_max = NA,
  roll_align = "right",
  water_year_start = 1,
  start_year,
  end_year,
  exclude_years,
  months = 1:12,
  months_min = NA,
  months_max = NA,
  complete_years = FALSE,
  ignore_missing = FALSE,
  allowed_missing = ifelse(ignore_missing, 100, 0),
  include_title = FALSE
)

Arguments

data: Data frame of daily data that contains columns of dates, flow values, and (optional) groups (e.g. station numbers). Leave blank or set to NULL if using station_number argument.
dates: Name of column in data that contains dates formatted YYYY-MM-DD. Only required if dates column name is not 'Date' (default). Leave blank or set to NULL if using station_number argument.
values: Name of column in data that contains numeric flow values, in units of cubic metres per second. Only required if values column name is not 'Value' (default). Leave blank if using station_number argument.
groups: Name of column in data that contains unique identifiers for different data sets, if applicable. Only required if groups column name is not 'STATION_NUMBER'. Function will automatically group by a column named 'STATION_NUMBER' if present. Remove the 'STATION_NUMBER' column beforehand to remove this grouping. Leave blank if using station_number argument.
station_number: Character string vector of seven digit Water Survey of Canada station numbers (e.g. "08NM116") of which to extract daily streamflow data from a HYDAT database. Requires tidyhydat package and a HYDAT database. Leave blank if using data argument.
roll_days: Numeric value of the number of days to apply a rolling mean. Default 1.
roll_days_min: Numeric value of the number of days to apply a rolling mean for low flows. Will override 'roll_days' argument for low flows. Default NA.
roll_days_max: Numeric value of the number of days to apply a rolling mean for high flows. Will override 'roll_days' argument for high flows. Default NA.
roll_align: Character string identifying the direction of the rolling mean from the specified date, either by the first ('left'), last ('right'), or middle ('center') day of the rolling n-day group of observations. Default 'right'.
water_year_start: Numeric value indicating the month (1 through 12) of the start of water year for analysis. Default 1.
start_year: Numeric value of the first year to consider for analysis. Leave blank or set well before start date (i.e. 1800) to use from the first year of the source data.
end_year: Numeric value of the last year to consider for analysis. Leave blank or set well after end date (i.e. 2100) to use up to the last year of the source data.
exclude_years: Numeric vector of years to exclude from analysis. Leave blank or set to NULL to include all years.
months: Numeric vector of months to include in analysis. For example, 3 for March, 6:8 for Jun-Aug or c(10:12,1) for first four months (Oct-Jan) when water_year_start = 10 (Oct). Default summarizes all months (1:12).
months_min: Numeric vector of specified months for window of low flows (3 for March, 6:8 for Jun-Aug). Will override 'months' argument for low flows. Default NA.
months_max: Numeric vector of specified months for window of high flows (3 for March, 6:8 for Jun-Aug). Will override 'months' argument for high flows. Default NA.
complete_years: Logical values indicating whether to include only years with complete data in analysis. Default FALSE.
ignore_missing: Logical value indicating whether dates with missing values should be included in the calculation. If TRUE then a statistic will be calculated regardless of missing dates. If FALSE then only those statistics from time periods with no missing dates will be returned. Default FALSE.
allowed_missing: Numeric value between 0 and 100 indicating the percentage of missing dates allowed to be included to calculate a statistic (0 to 100 percent). If 'ignore_missing = FALSE' then it defaults to 0 (zero missing dates allowed), if 'ignore_missing = TRUE' then it defaults to 100 (any missing dates allowed); consistent with ignore_missing usage. Supersedes ignore_missing when used.
include_title: Logical value to indicate adding the group/station number to the plot, if provided. Default FALSE.

Value

A list of ggplot2 objects with the following for each station provided:

Annual_Extreme_Flows: ggplot2 object of annual minimum and maximum flows of selected n-day rolling means
Annual_Extreme_Flows_Dates: ggplot2 object of the day of years of annual minimum and maximum flows of selected n-day rolling means

Examples

# Run if HYDAT database has been downloaded (using tidyhydat::download_hydat())
if (file.exists(tidyhydat::hy_downloaded_db())) {

# Plot annual 1-day (default) max/min flow data with 
# default alignment ('right')
plot_annual_extremes(station_number = "08NM116") 

# Plot custom annual 3-day max and 7-min flow data with 'center' alignment
plot_annual_extremes(station_number = "08NM116",
                     roll_days_max = 3,
                     roll_days_min = 7,
                     roll_align = "center")
                     
}
#> Warning: One or more calculations included missing values and NA's were produced. If desired, filter data for complete years or months, or use the 'ignore_missing' or 'allowed_missing' arguments (if applicable) to ignore or allow some missing values.
#> Warning: One or more calculations included missing values and NA's were produced. If desired, filter data for complete years or months, or use the 'ignore_missing' or 'allowed_missing' arguments (if applicable) to ignore or allow some missing values.
#> $Annual_Extreme_Flows

#> 
#> $Annual_Extreme_Flows_Dates

#>

Arguments

Value

See also

Examples