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Input reference

This section documents every SWAT+ input file. Each page lists:

  • the file's purpose
  • the Fortran reader and the derived type it populates
  • the column layout, units, defaults
  • a real example from the reference datasets
  • known bugs or quirks in an Important section at the bottom

Every page is verified against the SWAT+ source at a specific commit, recorded in the page frontmatter as verified_at_commit. The source code is the only authoritative reference; example datasets are downstream and can drift.

Simulation control

  • file.cio. Master index. Names every other input file.
  • time.sim. Simulation period and time step.
  • print.prt. Output selection and aggregation.
  • object.cnt. Basin name, areas, spatial object counts.

Basin parameters

Spatial objects and connectivity

  • *.con. Connectivity files (hru.con, chandeg.con, aquifer.con, reservoir.con, ...).
  • hru-data.hru. Per-HRU pointer table.
  • *.hyd, field.fld, shade_factor.shf. Per-HRU hydrology, topography, field geometry, and shade factor. Referenced by hru-data.hru.
  • recall. Point sources and inlets. Master recall.rec plus salt and constituent side databases and the region/element files.

Structural BMPs

  • *.str, septic.sep, urban.urb. Tile drains, septic systems and effluent, filter strips, grassed waterways, user-defined BMPs, saturated buffers, urban land cover.

Climate

  • *.cli. Index files: weather-sta.cli, weather-wgn.cli, pcp.cli, tmp.cli, slr.cli, hmd.cli, wnd.cli, pet.cli, atmodep.cli.
  • *.pcp. Precipitation data files.
  • *.tmp. Temperature data files.
  • *.tem. Legacy temperature file extension.
  • snow.sno. Snow parameter database.

Soils and land use

  • soils.sol. Soil profile and layer properties.
  • landuse.lum. Land-use management.
  • *.lum lookup tables. Curve number, conservation practice, and overland-flow Manning's n tables referenced by landuse.lum.

Initial conditions

  • *.ini. General initial conditions: plant.ini (plant communities), soil_plant.ini (soil water, residue, plant biomass), om_water.ini (organic matter in water bodies). Solute-side init files are covered in their module pages under Solute transport and Pollutants.

Channels, aquifers, reservoirs, wetlands

  • *.cha. Legacy channel files.
  • sd_channel. SWAT+ routing channel inputs (hydrology.cha, sediment.cha, nutrients.cha).
  • *.aqu. Aquifer files (aquifer.aqu, initial.aqu).
  • *.res. Reservoir files.
  • *.wet. Wetland files.

Groundwater

  • gwflow.*. 2D cell-based groundwater module inputs (mesh, channel coupling, tiles, ponds, canals, solutes, heat).

Operation and management databases

  • management.sch and minor inputs. Fixed-schedule management, puddle.ops, transplant.plt, co2.out, object.prt.
  • *.ops. harv, graze, irr, chem_app, fire, sweep.
  • *.dtl. Decision tables (lum.dtl, res_rel.dtl, scen_lu.dtl, flo_con.dtl).
  • plants.plt. Plant parameter database.
  • fertilizer.frt. Fertilizer composition and the manure type and organic-matter databases (manure_db.frt, manure_om.frt).
  • manure_allo.mnu. Manure allocation. Sources, demands, and the rule that distributes manure between them.
  • tillage.til. Tillage operations.
  • carb_coefs.cbn. Century carbon coefficients.
  • treatment.trt. Legacy treatment placeholder.

Water allocation

Solute transport

  • salt module. rtb-salt inputs: per-object initial conditions and applied loads for the eight salt ions.
  • cs module. rtb-cs inputs: master constituents.cs plus per-object initial conditions and applied loads for selenium, boron, and other constituents.

Pollutants

  • pesticide module. pesticide.pes parameter database, per-HRU and per-channel initial conditions, and the parent-daughter metabolite chain.
  • pathogen module. pathogens.pth parameter database and per-HRU and per-channel initial conditions.
  • metals module. Per-HRU initial heavy metal concentrations.

Verification procedure

The procedure for verifying a new or updated page is in SOURCE-OF-TRUTH.md in the docs working folder.