Monthly Volume Bias

Source: R/rvn_monthly_vbias.R

Creates a plot of the monthly volume biases in the simulated flow series.

rvn_monthly_vbias(
  sim,
  obs,
  add_line = TRUE,
  normalize = TRUE,
  add_labels = TRUE,
  incomplete_month = FALSE
)

Arguments

sim

time series object of simulated flows

obs

time series object of observed flows

add_line

optionally adds a horizontal line to the plot for reference (default TRUE)

normalize

option to normalize the biases and report as percent error (default TRUE)

add_labels

optionally adds labels for early peak/late peaks on right side axis (default TRUE)

incomplete_month

whether to include months with missing days in the summation (default FALSE)

Value

mvbias

monthly volume biases

Details

Calculates the monthly volume biases and optionally creates a plot of them. The monthly volume biases are averaged across all years of data. If normalized, the biases are calculated as:

(Vi_sim - Vi_obs)/Vi_obs*100

to be expressed as a percent error.

The sim and obs should be of time series (xts) format and are assumed to be of the same length and time period. The flow series are assumed to be daily flows with units of m3/s. Note that a plot title is purposely omitted in order to allow the automatic generation of plot titles.

The add_labels will add the labels of 'overestimated' and 'underestimated' to the right hand side axis if set to TRUE. This is useful in interpreting the plots. Note that the biases are calculated as sim_Volume - obs_Volume, which means that negative values mean the volume is underestimated, and positive values mean the volume is overestimated.

See also

rvn_annual_volume to create a scatterplot of annual flow volumes

Examples

# load sample hydrograph data, two years worth of sim/obs
data(rvn_hydrograph_data)
sim <- rvn_hydrograph_data$hyd$Sub36
obs <- rvn_hydrograph_data$hyd$Sub36_obs

# check the monthly volume bias; normalizes by default
rvn_monthly_vbias(sim, obs)
#> Number of months excluded: 1
#> Number of months included: 23
#> $df.mvbias
#>          mvbias
#> Jan  26.4767246
#> Feb -30.1912953
#> Mar  13.1917920
#> Apr -29.6779258
#> May -61.6461393
#> Jun -55.1406116
#> Jul -68.9622504
#> Aug -70.4903267
#> Sep  33.0222767
#> Oct   0.8430192
#> Nov  81.6977124
#> Dec  25.5154499
#> 
#> $plot

#> 

# check unnormalzied monthly volume biases; see the larger volumes in certain periods
rvn_monthly_vbias(sim,obs,normalize = FALSE)
#> Number of months excluded: 1
#> Number of months included: 23
#> $df.mvbias
#>          mvbias
#> Jan   11.544355
#> Feb  -12.105343
#> Mar   62.659294
#> Apr  -73.400235
#> May -194.812215
#> Jun  -70.241846
#> Jul  -34.557970
#> Aug  -49.736272
#> Sep    7.026953
#> Oct    0.850050
#> Nov  -38.586910
#> Dec  -26.795530
#> 
#> $plot

#>