add_cumulative_volume {fasstr}

Add a daily cumulative volumetric flows column to daily flows

Description

Add a column of rolling daily cumulative volumetric flows on an annual basis to a daily streamflow data set. Adds the volumetric discharge from each day with the previous day(s) for each year, in units of cubic metres. The cumulative flows restart every year and are only calculated in years with complete data.

Usage

add_cumulative_volume(
  data,
  dates = Date,
  values = Value,
  groups = STATION_NUMBER,
  station_number,
  water_year_start = 1,
  months = 1:12
)

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.

water_year_start

Numeric value indicating the month (1 through 12) of the start of water year for analysis. Default 1.

months

Numeric vector of months to add cumulative flows (e.g. 6:8 for Jun-Aug). Default accumulates to full years using all months (1:12).

Value

A tibble data frame of the source data with an additional column:

Cumul_Volume_m3

cumulative volumetric flows for each day for each year, in units of cubic metres

Examples

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

# Add a column based on water years starting in August
add_cumulative_volume(station_number = "08NM116", 
                      water_year_start = 8)
                      
}