Calculate annual timing of flows

Calculates the timing (day of year and date) of portions of total annual flow of daily flow values from a daily streamflow data set. Calculates statistics from all values from complete years, unless specified. Returns a tibble with statistics.

calc_annual_flow_timing(
  data,
  dates = Date,
  values = Value,
  groups = STATION_NUMBER,
  station_number,
  percent_total = c(25, 33.3, 50, 75),
  water_year_start = 1,
  start_year,
  end_year,
  exclude_years,
  months = 1:12,
  transpose = 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.

percent_total

Numeric vector of percents of total annual flows to determine dates. Default c(25,33.3,50,75).

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).

transpose

Logical value indicating whether to transpose rows and columns of results. Default FALSE.

Value

A tibble data frame with the following columns:

Year

calendar or water year selected

DoY_'n'pct_TotalQ

day of year for each n-percent of total volumetric discharge

Date_'n'pct_TotalQ

date (YYYY-MM-DD) for each n-percent of total volumetric discharge

Default columns:

DoY_25pct_TotalQ

day of year of 25-percent of total volumetric discharge

Date_25pct_TotalQ

date (YYYY-MM-DD) of 25-percent of total volumetric discharge

DoY_33.3pct_TotalQ

day of year of 33.3-percent of total volumetric discharge

Date_33.3pct_TotalQ

date (YYYY-MM-DD) of 33.3-percent of total volumetric discharge

DoY_50pct_TotalQ

day of year of 50-percent of total volumetric discharge

Date_50pct_TotalQ

date (YYYY-MM-DD) of 50-percent of total volumetric discharge

DoY_75pct_TotalQ

day of year of 75-percent of total volumetric discharge

Date_75pct_TotalQ

date (YYYY-MM-DD) of 75-percent of total volumetric discharge

Transposing data creates a column of 'Statistics' (just DoY, not Date values) and subsequent columns for each year selected.

References

• Barnett, T.P., Pierce, D.W., Hidalgo, H.G., Bonfils, C., Santer, B.D., Das, T., Bala, G., Wood, A.W., Nozawa, T., Mirin, A.A., Cayan, D.R., Dettinger, M.D., 2008. Human-Induced Clanges in the Hydrology of the Western United States. Science 319, 1080-1083.

Examples

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

# Calculate annual flow timings with default percent of annual totals
calc_annual_flow_timing(station_number = "08NM116") 

# Calculate annual flow timings with custom percent of annual totals
calc_annual_flow_timing(station_number = "08NM116",
                        percent_total = 50)
                             
}
#> 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.
#> # A tibble: 72 × 4
#>    STATION_NUMBER  Year DoY_50pct_TotalQ Date_50pct_TotalQ
#>    <chr>          <dbl>            <dbl> <date>           
#>  1 08NM116         1949               NA NA               
#>  2 08NM116         1950               NA NA               
#>  3 08NM116         1951               NA NA               
#>  4 08NM116         1952               NA NA               
#>  5 08NM116         1953               NA NA               
#>  6 08NM116         1954               NA NA               
#>  7 08NM116         1955               NA NA               
#>  8 08NM116         1956               NA NA               
#>  9 08NM116         1957               NA NA               
#> 10 08NM116         1958               NA NA               
#> # … with 62 more rows