Skip to content

Calibration

SWAT+ supports two calibration modes that are configured and run from inside the model.

  • Hard calibration fits named model parameters to observed time series (streamflow, sediment, nutrient loads). Parameter values are perturbed within absolute bounds, the model is re-run, and the simulation is compared with measured data. Implemented in calhard_*.f90. Driven by cal_parms.cal (parameter definitions and bounds) and calibration.cal (the change list applied each run).
  • Soft calibration adjusts process outputs toward regional water-balance and yield targets without exposing the underlying parameters as a sample space. Targets are expressed as fractions of precipitation for the water balance, channel sediment budgets, and plant growth. Implemented in calsoft_*.f90. Driven by codes.sft, wb_parms.sft, water_balance.sft, ch_sed_budget.sft, ch_sed_parms.sft, plant_parms.sft, and plant_gro.sft.

The two modes share the same internal parameter selector (cal_parm_select.f90) and the same conditional change machinery (cal_conditions.f90).

Pages

  • Hard calibration. Parameter perturbation, sources, the role of calibration.cal.
  • Soft calibration. Regional water balance and yield targets, sources, the role of codes.sft.
  • Parameter change files. Format of cal_parms.cal and calibration.cal, verified against the readers.
  • Conditions and regionalization. Applying a change only to HRUs that match a condition (HSG, texture, plant, land use, calibration group).
  • Sensitivity workflow. Driving SWAT+ from an external tool to compute sensitivity indices, using the same cal_parms.cal to define the sample space.