Code structure

FSoilTH/
├── app/FSoilTH.F90              standalone driver
├── src/core/                    parameters, constants, grid and state
├── src/physics/                 hydrology and heat processes
├── src/numerics/                reusable solvers
├── src/io/                      NetCDF utilities
├── cases/maqu_2022-06/          first development case
├── config/machines/             build profiles
├── docs/                        model documentation
├── Makefile
└── mkdocs.yml

Current modules

Layer	Modules	Current responsibility
Core	ModelParameterMod, SoilParameterMod, SoilConstantMod	Run parameters, soil parameters and constants
State	SoilTypeMod	Grid/state types and prototype initialization
Physics	SoilHydrologyMod, SoilTemperatureMod	Hydraulic/thermal properties and solvers
Numerics	TridiagonalMod	Tridiagonal linear-system solver
I/O	EmptyNetcdfMod, NetcdfReadMod, NetcdfWriteMod	NetCDF utility routines
Application	FSoilTH.F90	Current prototype call chain

Intended evolution

The next architecture stage will separate grid, state and initialization; split physical properties from equation solvers; unify NetCDF error handling; and expose a driver-independent model lifecycle. Module splitting will occur only after regression tests protect the existing behavior.