gr_join_rean {grwat}

Join reanalysis data

Description

The function performs spatial join of meteorological variables (temperature and precipitation) from grwat reanalysis to the daily runoff time series. Reanalysis covers the East European Plain with 0.75 degrees spatial resolution and is obtained based on CIRES-DOE (1880-1949) and ERA5 (1950-2021) data. This function is useful when the data from meteorological stations are missing inside the basin.

Usage

gr_join_rean(hdata, rean, buffer)

Arguments

hdata

data.frame containing 2 columns: Date and runoff

rean

list as returned by gr_read_rean()

buffer

sf object containing the region to select reanalysis data. Usually a river basin is used to select the meteorological data. Use gr_buffer_geo() to buffer the basin by specified distance and get more data, if needed.

Details

Download the reanalysis archive from here.

Value

data.frame with four columns: date, runoff, temperature, precipitation.

Examples

if (require("sf") && require("ncdf4")) {

  library(grwat)
  library(dplyr)

  # example Spas-Zagorye daily runoff data is included with grwat package
  data_path = system.file("extdata", "spas-zagorye.txt",
                          package = "grwat")

  hdata_raw = read.delim(data_path, header = FALSE, 
                         sep = ' ', na.strings = c('-999', '-999.0', '-'),
                         col.names = c('d', 'm', 'y', 'q'))

  hdata = hdata_raw %>%
    transmute(Date = lubridate::make_date(y, m, d),
              Q = q)

  head(hdata)

  # read basin
  basin_path = system.file("extdata", "spas-zagorye.gpkg",
                           package = "grwat")
  basin = sf::st_read(basin_path, layer = 'basin') # read basin region
  basin_buffer = gr_buffer_geo(basin, 25000)

  ## Not run: 
    # read reanalysis data
    rean = gr_read_rean(
      '/Volumes/Data/Spatial/Reanalysis/grwat/pre_1880-2021.nc',
      '/Volumes/Data/Spatial/Reanalysis/grwat/temp_1880-2021.nc'
    )

    # spatial join of reanalysis data to runoff data
    hdata_rean = gr_join_rean(hdata, rean, basin_buffer)

    head(hdata_rean)
  
## End(Not run)

}