wcswatin

Overview

wcswatin (Weather & Climate SWAT Input) is an open-source R package for preparing weather and climate data from different sources for input in the Soil & Water Assessment Tool (SWAT).

The package provides two main workflows:

• Raster/NetCDF Processing: Extract and process climate data from global gridded datasets (ERA5-Land, GPM IMERG, PERSIANN, etc.)
• Station Data Interpolation: Upscale point measurements from weather stations using trend surface interpolation

Developed with funding from the Critical Ecosystem Partnership Fund (CEPF).

Key Features

• Process NetCDF and GeoTIFF raster files from multiple climate data providers
• Spatial and temporal data extraction for specific watersheds
• Trend surface interpolation for station data upscaling
• Gap-filling routines for station data
• Direct output formatting for SWAT model input files
• Optimized for large datasets with parallel processing support

Installation

Install the development version from GitHub:

# install.packages("devtools")
devtools::install_github("reginalexavier/wcswatin")

Quick Start

library(wcswatin)

# Process NetCDF climate data
climate_data <- input_raster(
  raster_file = "path/to/climate_data.nc",
  watershed = "path/to/watershed.shp",
  var_name = "precipitation"
)

# Interpolate station data
station_data <- ts_to_point(
  my_folder = "path/to/station_files",
  targeted_points_path = "path/to/centroids.shp",
  poly_degree = 2
)

Workflow Overview

Conceptual workflow of the wcswatin package

Main Functions

Data Input & Loading

• input_raster(): Load NetCDF or GeoTIFF files as SpatRaster objects
• input_table(): Load tabular data with validation
• input_vector(): Load spatial vector data (shapefiles, etc.)
• var_names(): List available variables in NetCDF files

Raster/NetCDF Processing

• study_area_records(): Extract grid points within watershed boundaries
• layervalues2pixel(): Extract time series for each grid cell
• cube2table(): Convert raster data cube to tabular format
• daily_aggregation(): Aggregate raster data to daily time steps
• tbl_from_references(): Extract raster values at reference points

Station Data Processing

• point_to_daily(): Import and organize daily station data
• files_to_table(): Consolidate multiple station files into a single table
• table_to_files(): Split consolidated data back into individual files
• fill_gap(): Fill missing data using correlation methods
• ts_to_point(): Trend surface interpolation to specific points (watershed centroids)
• ts_to_area(): Trend surface interpolation to create continuous raster surfaces
• save_daily_tbl(): Save daily tables in SWAT format

SWAT-Specific Functions

• var_main_creator(): Generate SWAT input metadata tables
• main_input_var(): Create main variable input tables for SWAT
• rh_calculator(): Calculate relative humidity from other variables
• windspeed_calculator(): Calculate wind speed from components

Data Analysis & Utilities

• count_na(): Check data completeness and missing values
• summary_table(): Generate statistical summaries
• summary_plot(): Visualize data distributions
• unit_converter(): Convert between measurement units

Data Requirements

The package works with spatial data in WGS 84 geographic coordinate system (EPSG:4326), which is the standard format for most climate datasets.

Supported Data Sources

• Climate Reanalysis: ERA5-Land, MERRA-2, NCEP
• Satellite Precipitation: GPM IMERG, PERSIANN, CHIRPS
• Station Data: Standard SWAT weather file format

Documentation

• Vignettes: Detailed tutorials and workflows
• Function Reference: ?function_name or visit package documentation
• Examples: Run example(function_name) for usage examples

Getting Help

• Bug Reports: GitHub Issues
• Contact:
  • Réginal Exavier: reginalexavier@rocketmail.com
  • Peter Zeilhofer: zeilhoferpeter@gmail.com

Citation

If you use wcswatin in your research, please cite:

@software{wcswatin2025,
  author = {Exavier, Reginal and Zeilhofer, Peter},
  title = {wcswatin: Weather & Climate SWAT Input},
  year = {2025},
  url = {https://github.com/reginalexavier/wcswatin}
}

License

GPL (>= 3)

Acknowledgments

This project is funded by the Critical Ecosystem Partnership Fund (CEPF).

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Note: This package is under active development. Functions and features may change.