Soft calibration

Soft calibration nudges model outputs toward regional targets expressed as fractions of precipitation (water balance), per-stream-order channel sediment budgets, and per-region plant yields. The targets are user-supplied and the model adjusts a small fixed set of parameters internally until each component falls inside its target window. Soft calibration is run separately from a normal simulation; it loops over the relevant land-use regions and process components, updates parameters, and re-runs the affected balance routine.

Components¶

The soft codes file (codes.sft) is read by calsoft_read_codes.f90 into cal_codes (type soft_calibration_codes in calibration_data_module.f90). Each switch enables one component of the soft calibration:

Code	Switch	Component	Driver routine
`hyd_hru`	`n`, `a`, `b`, `y`	HRU water balance by land use in each region. `a` calibrates all components (ET, surface runoff, lateral flow, percolation). `b` calibrates baseflow and total runoff only.	`calsoft_hyd.f90`, `calsoft_hyd_bfr.f90`
`hyd_hrul`	`y`/`n`	`hru_lte` water balance by land use in each region	`caltsoft_hyd.f90`
`plt`	`y`/`n`	Plant growth (LAI, harvest index) by region	`calsoft_plant.f90`
`sed`	`y`/`n`	Upland sediment yield by land use in each region	`calsoft_sed.f90`
`nut`	`y`/`n`	HRU nutrient balance by land use in each region	(gated in `calsoft_control.f90`)
`chsed`	`y`/`n`	Channel widening and bank accretion by stream order	(gated in `calsoft_control.f90`)
`chnut`	`y`/`n`	Channel nutrient balance by stream order	(gated in `calsoft_control.f90`)
`res`	`y`/`n`	Reservoir budgets by reservoir	(gated in `calsoft_control.f90`)

If any switch is non-default the master flag cal_soft is set to "y" and calsoft_control is called instead of (or alongside) the normal simulation.

HRU water balance¶

calsoft_hyd.f90 is the full water-balance loop. It iterates over land-use regions, reads the regional water-balance targets (water_balance.sft) and the per-parameter perturbation envelope (wb_parms.sft), and adjusts the active parameter set until each component is within tolerance. The components and their helper routines are:

PET, calsoft_hyd_bfr_pet.f90
ET, calsoft_hyd_bfr_et.f90
Surface runoff, calsoft_hyd_bfr_surq.f90
Lateral flow, calsoft_hyd_bfr_latq.f90
Percolation, calsoft_hyd_bfr_perc.f90

The shared baseflow ratio loop is calsoft_hyd_bfr.f90.

Adjustable parameters for the upland water balance are read into ls_prms (type soft_calib_parms). Each entry carries a parameter name, the change type (absval, abschg, or pctchg), and neg/pos perturbation limits with absolute floor/ceiling values.

Channel sediment¶

ch_sed_budget.sft carries the per-stream-order sediment budget targets. ch_sed_parms.sft carries the perturbation envelope for channel sediment parameters, read into ch_prms. The channel sediment block is gated in calsoft_control.f90 but the call to a calsoft_chsed driver is commented out in the current source; only the per-order accounting loop runs.

Plant growth¶

plant_parms.sft defines the plant parameter envelope (LAI potential, harvest index) and plant_gro.sft carries the per-region plant target table. The driver is calsoft_plant.f90; calsoft_plant_zero.f90 zeros the running statistics between iterations. After soft calibration writes the new plant parameter values, pl_write_parms_cal dumps a fresh plants.plt and a hydrology-cal.hyd snapshot.

Outputs¶

calsoft_control.f90 writes:

hydrology-cal.hyd (unit 5001) with per-HRU hydrology parameters after the run.
A channel sediment summary (unit 5000) when chsed = y.

These outputs are intended to be copied back into the model inputs to lock in the soft-calibrated values.

Input files¶

File	Read by	Purpose
`codes.sft`	`calsoft_read_codes.f90`	Component switches.
`wb_parms.sft`	(read in `calsoft_init`)	Upland water-balance parameter envelope.
`water_balance.sft`	(read in `calsoft_init`)	Regional water-balance targets (SR, LF, PC, ET, TF as fractions of precipitation).
`ch_sed_budget.sft`	(read in `calsoft_init`)	Channel sediment budget targets by stream order.
`ch_sed_parms.sft`	(read in `calsoft_init`)	Channel sediment parameter envelope.
`plant_parms.sft`	(read in `calsoft_init`)	Plant parameter envelope.
`plant_gro.sft`	(read in `calsoft_init`)	Per-region plant yield targets.

All *.sft slots are declared in input_file_module.f90, type input_chg. Set the slot to null (or remove the file) to skip a component.

Hard calibration. Use after soft calibration to fit remaining parameters to observed time series.
Parameter change files. cal_parms.cal defines the parameter universe and bounds shared with hard calibration.