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Summarize SWAT output data

Source: R/output_analysis.R
summarize_swat_output.Rd

Processes SWAT model output data from reaches, subbasins, or HRUs and aggregates them at different temporal and spatial scales.

- If the input data are daily, they are aggregated to monthly and then to annual scale.
- If the input data are monthly, they are aggregated directly to annual scale.

Additionally, the function computes climatological summaries:
- Mean annual cycle and mean annual values for each simulated variable at the HRU, subbasin, or reach level.
- Mean annual values by land use/land cover (LULC) for HRU outputs.
- Basin-wide climatological summaries, including mean annual cycle and mean annual values, which are area-weighted averages across the entire watershed (only for subbasin and HRU outputs).

Usage

summarize_swat_output(swat_output, water_year = FALSE, water_year_start = 9)

Arguments

swat_output

A data frame containing SWAT output data, typically read using the output_rch, output_sub, or output_hru functions.

water_year

Logical. If `TRUE`, adjusts data to hydrological years, starting from the specified month.

water_year_start

Integer. The month to start the hydrological year (default is 9 for September).

Value

A list containing:

  • `daily`: Original daily data (if the input is daily, otherwise `NULL`).

  • `monthly`: Aggregated monthly data or original input if already monthly.

  • `annual`: Aggregated annual data.

  • `mean_annual`: Mean annual values for each HRU, subbasin, or reach.

  • `mean_annual_cycle`: Mean monthly climatology for each HRU, subbasin, or reach.

  • `mean_annual_LULC`: Mean annual values aggregated by land use/land cover (only for HRUs).

  • `mean_annual_basin`: Area-weighted mean annual values across the entire basin (only for subbasins and HRUs).

  • `mean_annual_cycle_basin`: Area-weighted mean monthly climatology across the entire basin (only for subbasins and HRU outputs).

  • `basin_area`: Total area of the basin (only for subbasin and HRU outputs).

See also

output_rch, output_sub, output_hru

Examples

# --- Example with Reach data ---
tmpdir <- tempdir()
get_swat_example(tmpdir)
rch_file <- file.path(tmpdir, "TxtInOut", "output.rch")
rch_data <- output_rch(file = rch_file, variable = c("FLOW_OUTcms"),
                       target_id = NULL, time_step = "daily",
                       output_start_date = "2011-01-01")
summary_rch <- summarize_swat_output(rch_data)
names(summary_rch)

# --- Example with Subbasin data ---
sub_file <- file.path(tmpdir, "TxtInOut", "output.sub")
sub_data <- output_sub(file = sub_file,
                       variable = c("AREAkm2", "PRECIPmm", "ETmm", "WYLDmm"),
                       target_id = NULL, time_step = "daily",
                       output_start_date = "2011-01-01")
summary_sub <- summarize_swat_output(sub_data, water_year = TRUE)
head(summary_sub$mean_annual)

# --- Example with HRU data ---
hru_file <- file.path(tmpdir, "TxtInOut", "output.hru")
hru_data <- output_hru(file = hru_file,
                       variable = c("AREAkm2", "PRECIPmm", "ETmm", "WYLDmm"),
                       target_id = NULL, time_step = "daily",
                       output_start_date = "2011-01-01")
summary_hru <- summarize_swat_output(hru_data)
head(summary_hru$mean_annual_LULC)