Trend Test — trend_test • HASP

Test for period of record and user-specified ranges. The default trends are calculated for 10 year and the full period of record.

Usage

trend_test(
  gw_level_dv,
  gwl_data,
  n_years = 10,
  parameter_cd = NA,
  date_col = c("time", "time"),
  value_col = c("value", "value"),
  approved_col = c("approval_status", "approval_status"),
  pctComplete = 0.5,
  days_required_per_month = 14,
  POR_trend = TRUE
)

Arguments

gw_level_dv: data frame, daily groundwater level data. Often obtained from read_waterdata_daily. Use NULL for no daily data.
gwl_data: data frame returned from read_waterdata_field_measurements, or data frame with a date, value, and approval columns. Use NULL for no discrete data.
n_years: integer. This is the number of years to calculate the trend on. Default is 10. This can be a vector of years.
parameter_cd: Can be used to filter data if the data frame has a "parameter_code" column. The default is NA, which will not do any filtering. If the gwl_data and gw_level_dv need different parameter code filtering, use a vector of 2 parameter codes. The first one will filter the gw_level_dv data frame, the second will filter the gwl_data data frame.
date_col: the name of the time columns. The first value is associated with the gw_level_dv input, and the second value is associated with the gwl_data input. The default is c("time", "time").
value_col: the name of the value columns. The first value is associated with the gw_level_dv input, and the second value is associated with the gwl_data input. The default is c("value", "value").
approved_col: the name of the column to get provisional/approved status. The first value is associated with the gw_level_dv input, and the second value is associated with the gwl_data input. The default is c("approval_status", "approval_status"). It is expected that these columns will have only "Approved" or "Provisional".
pctComplete: number percentage complete. This is a fraction that represents the amount of data that must be included overall in order to calculate a trend. The default is 0.5, which means if gaps in the data span more than 50 total record, a trend will not be calculated.
days_required_per_month: integer. Number of days required per month to include in the trend test. Default is 14.
POR_trend: a logical indicating whether to include a trend test for the full period of record. Default is TRUE.

Value

a data frame of test results from 5 and 20 year Kendall Seasonal Trend test

Details

For data that is at least on a daily interval, the rkt function is used. For periodic data, the kendallTrendTest is used.

Examples


site <- "USGS-263819081585801"
p_code_dv <- "62610"
statCd <- "00001"

# Using package example data:
# gwl_data <- dataRetrieval::read_waterdata_field_measurements(monitoring_location_id = site)
gwl_data <- L2701_example_data$Discrete
                        
# gw_level_dv <- dataRetrieval::read_waterdata_daily(monitoring_location_id = site,
#                                                    parameter_code = p_code_dv,
#                                                    statistic_id = statCd)
                                                    
gw_level_dv <- L2701_example_data$Daily

trend_test(gw_level_dv,
           gwl_data,
           parameter_cd = "62610")
#>               test        tau       pValue      slope  intercept trend
#> 1    10-year trend  0.5724638 1.332268e-15  1.2550504 -2553.3877    Up
#> 2 Period of record -0.1574455 7.990754e-08 -0.1399705   258.9394  Down
           
trend_test(gw_level_dv,
           gwl_data,
           POR_trend = FALSE,
           parameter_cd = "62610")
#>            test       tau       pValue   slope intercept trend
#> 1 10-year trend 0.5724638 1.332268e-15 1.25505 -2553.388    Up
           
trend_test(gw_level_dv,
           gwl_data,
           parameter_cd = "62610",
           n_years = 5)
#>               test        tau       pValue      slope  intercept trend
#> 1     5-year trend  0.5703704 7.133504e-07  1.7944792 -3644.6155    Up
#> 2 Period of record -0.1574455 7.990754e-08 -0.1399705   258.9394  Down
           
trend_test(gw_level_dv,
           gwl_data,
           parameter_cd = "62610",
           n_years = c(5, 10, 20))
#>               test        tau       pValue      slope  intercept trend
#> 1     5-year trend  0.5703704 7.133504e-07  1.7944792 -3644.6155    Up
#> 2    10-year trend  0.5724638 1.332268e-15  1.2550504 -2553.3877    Up
#> 3    20-year trend  0.7321348 0.000000e+00  1.3146453 -2673.5277    Up
#> 4 Period of record -0.1574455 7.990754e-08 -0.1399705   258.9394  Down

# Only periodic data:
trend_test(NULL,
           gwl_data,
           parameter_cd = "62610")
#>               test         tau       pValue    slope intercept           trend
#> 1    10-year trend  0.46293706 4.023179e-08 1.249909 -2542.532              Up
#> 2 Period of record -0.02290433 5.209615e-01       NA        NA Not significant