calc_monthly_cumulative_stats: Calculate cumulative monthly flow statistics

In fasstr: Analyze, Summarize, and Visualize Daily Streamflow Data

Calculate cumulative monthly flow statistics

Description

Calculate cumulative monthly flow statistics for each month of the year of daily flow values from a daily streamflow data set. Calculates statistics from all values from complete years, unless specified. Defaults to volumetric cumulative flows, can use use_yield and basin_area to convert to area-based water yield. Returns a tibble with statistics.

Usage

calc_monthly_cumulative_stats(
  data,
  dates = Date,
  values = Value,
  groups = STATION_NUMBER,
  station_number,
  percentiles = c(5, 25, 75, 95),
  use_yield = FALSE,
  basin_area,
  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.
percentiles	Numeric vector of percentiles to calculate. Set to NA if none required. Default c(5,25,75,95).
use_yield	Logical value indicating whether to calculate area-based water yield, in mm, instead of volumetric discharge. Default FALSE.
basin_area	Upstream drainage basin area, in square kilometres, to apply to observations. Three options: (1) Leave blank if groups is STATION_NUMBER with HYDAT station numbers to extract basin areas from HYDAT. (2) A single numeric value to apply to all observations. (3) List each basin area for each group/station in groups (can override HYDAT value if listed) as such c("08NM116" = 795, "08NM242" = 10). If group is not listed the HYDAT area will be applied if it exists, otherwise it will be NA.
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). Need to be consecutive months for given year/water year to work properly.
transpose	Logical value indicating whether to transpose rows and columns of results. Default FALSE.

Value

A tibble data frame with the following columns, default units in cubic metres, or millimetres if use_yield and basin_area provided:

Month	month (MMM-DD) of cumulative statistics
Mean	monthly mean of all cumulative flows for a given month of the year
Median	monthly mean of all cumulative flows for a given month of the year
Maximum	monthly mean of all cumulative flows for a given month of the year
Minimum	monthly mean of all cumulative flows for a given month of the year
P'n'	each monthly n-th percentile selected of all cumulative flows for a given month of the year

Default percentile columns:

P5	monthly 5th percentile of all cumulative flows for a given month of the year
P25	monthly 25th percentile of all cumulative flows for a given month of the year
P75	monthly 75th percentile of all cumulative flows for a given month of the year
P95	monthly 95th percentile of all cumulative flows for a given month of the year

Transposing data creates a column of "Statistics" and subsequent columns for each year selected.

Examples

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

# Calculate annual monthly cumulative volume statistics
calc_monthly_cumulative_stats(station_number = "08NM116") 

# Calculate annual monthly cumulative volume statistics with default HYDAT basin area
calc_monthly_cumulative_stats(station_number = "08NM116",
                              use_yield = TRUE) 

# Calculate annual monthly cumulative volume statistics with custom basin area
calc_monthly_cumulative_stats(station_number = "08NM116",
                              use_yield = TRUE,
                              basin_area = 800) 
                              
}

fasstr documentation built on Sept. 30, 2024, 9:24 a.m.