Table 1.

Selected new options implemented into HYDRUS-1D since 2008.

VersionNew options
4.01
  • Vapor flow (both thermal and isothermal)

  • Coupled water, vapor, and energy transport (thermal and isothermal, in the liquid and gaseous phases) (Saito et al., 2006)

  • Dual-permeability type water flow and solute transport (Gerke and van Genuchten, 1993)

  • Dual-porosity water flow and solute transport with solute transport subjected to two-site sorption in the mobile zone (Šimůnek and van Genuchten, 2008)

  • Potential evapotranspiration calculated using the Penman–Monteith combination equation (FAO, 1990) or the Hargreaves equation (Hargreaves, 1994)

  • Seepage face boundary conditions with a specified pressure head

  • Daily variations in evaporation and transpiration rates generated by HYDRUS from daily values

  • Full graphical user interface support for the HP1 program (Jacques et al., 2008a,b)

4.04
  • Option to specify the nonequilibrium phase concentrations to be initially at equilibrium with the equilibrium phase concentration

  • Option to specify initial conditions in total (instead of liquid) concentrations. The program then redistributes the solute mass into individual phases based on distribution coefficients

4.05
  • Support for the dual-porosity (mobile–immobile water) model in HP1

  • Linking optimized parameters (which can be made the same) of different soil layers

  • Keeping a constant mobile water content in multiple layers (in the dual-porosity model) when optimizing the immobile water content

4.06
  • Tortuosity models by Moldrup et al. (1997, 2000) as an alternative to the Millington and Quirk (1961) model

4.07
  • Surface energy balance (i.e., the balance of latent, heat, and sensible fluxes) for bare soils (Saito et al., 2006)

  • Daily variations in meteorological variables can be generated by the model using simple meteorological models

  • Preliminary (at present rather simple) support of the HYDRUS package for MODFLOW (Twarakavi et al., 2008)

4.08
  • Uncompensated and compensated root water and solute (passive and active) uptake (Šimůnek and Hopmans, 2009)

4.12
  • Additional output (e.g., solute fluxes at observation nodes and profiles of various hydraulic conductivities [thermal and isothermal] and certain fluxes [liquid, vapor, thermal, isothermal, and total])

4.13
  • New version (2.1.002) of HP1, a new graphical user interface supporting HP1

  • Automatic conversion of units for the threshold–slope salinity stress model from electric conductivities (dS m−1) to osmotic heads (m)

4.15
  • Input of a sublimation constant and an initial snow layer

  • Conversion of constants (from electrical conductivity units to units of the osmotic potential) in the salinity stress response functions

4.16
  • Option to define field capacity as an initial condition (Twarakavi et al., 2009)

  • Display of wetting hydraulic functions for hysteretic soils

  • Triggered irrigation, that is, irrigation can be triggered when the pressure head at a particular observation node drops below a specified value (Dabach et al., 2013)

  • Interception can be considered with the standard HYDRUS input (without needing meteorological input)

4.17
  • Graphs for all meteorological/energy fluxes (when meteorological data are considered)

  • Drainage fluxes (to horizontal drains) can be either through the bottom of the soil profile or vertically distributed along the saturated zone.