The HPx software for multicomponent reactive transport during variably-saturated flow: Recent developments and applications

Abstract

HPx is a multicomponent reactive transport model which uses HYDRUS as the flow and transport solver and PHREEQC-3 as the biogeochemical solver. Some recent adaptations have significantly increased the flexibility of the software for different environmental and engineering applications. This paper gives an overview of the most significant changes of HPx, such as coupling transport properties to geochemical state variables, gas diffusion, and transport in two and three dimensions. OpenMP allows for parallel computing using shared memory. Enhancements for scripting may eventually simplify input definitions and create possibilities for defining templates for generic (sub)problems. We included a discussion of root solute uptake and colloid-affected solute transport to show that most or all of the comprehensive features of HYDRUS can be extended with geochemical information. Finally, an example is used to demonstrate how HPx, and similar reactive transport models, can be helpful in implementing different factors relevant for soil organic matter dynamics in soils. HPx offers a unique framework to couple spatial-temporal variations in water contents, temperatures, and water fluxes, with dissolved organic matter and CO 2 transport, as well as bioturbation processes.

Soil salinization in very high-density olive orchards grown in southern Portugal: Current risks and possible trends

“…The major ion chemistry module adapted from the UNSATCHEM model (Šimůnek et al, 2016) allows for the simulation of multicomponent solute transport, describing the subsurface transport of multiple ions that may mutually interact, create various complex species, compete for sorption sites, and/or precipitate or dissolve (Gonçalves et al, 2006;Ramos et al, 2011;Rasouli et al, 2013;Raij et al, 2016). Finally, the HPx module (Jacques et al, 2018), in contrast to the previous module which is constrained to specific elements, offers users the flexibility to simulate multicomponent solute transport while defining their own species with particular chemical properties and reactions. However, to the best of our knowledge, no applications related to salinity problems have been yet reported using HPx.…”

Numerical Simulation of the Effect of Chemical Osmosis on the Value of the Jumps of Pollution in the Geochemical Barrier

“…Soil parameters for the numerical experiments are taken from the Hydrus-1D program [8]. As the main soil, loam with k 0 = 0.028m/day, θ min = 0.1, θ max = 0.38, n = 1.23, α = 2.7 day −1 were considered.…”

“…where D 1 is the hydrodynamic dispersion coefficient; D 2 is the molecular diffusion coefficient. According to [8,18]…”

Development of a Fully Coupled Biogeochemical Reactive Transport Model to Simulate Microbial Oxidation of Organic Carbon and Pyrite Under Nitrate‐Reducing Conditions

“…Numerical investigations were carried out with the code HP1 (Jacques et al, 2018), which is a numerical solver for multicomponent reactive transport for variably saturated water flow conditions. It couples HYDRUS-1D (Šimůnek et al, 2016) for solving the Richards equation and the advection-dispersion equation with PHREEQC (Parkhurst & Appelo, 2013) for solving the biogeochemical processes to simulate multicomponent reactive transport in variable saturated porous media.…”