Hydrologic Transport and Mixed Geochemical Kinetic/Equilibrium Model

HYDROGEOCHEM 2 is a modification of HYDROGEOCHEM which was designed to solve coupled hydrologic transport and geochemical equilibrium problems. The modification includes replacement of the EQMOD chemical equilibrium subroutines by a mixed chemical Kinetic and Equilibrium Model (KEMOD) to deal with species whose concentrations are controlled by either thermodynamics or kinetics. HYDROGEOCHEM2 is a coupled model of hydrologic transport and geochemical reaction in saturated-unsaturated media. HYDROGEOCHEM 2 comprises two basic modules: the transport module and the geochemical reaction module. The transport module is designed to simulate: (1) transient and/or steady-state transport of N saqueous components, (2) transient and/or steady-state mass balance of N sadsorbent components and NSITE ion-exchange sites. The geochemical reaction module is designed to compute the species distribution of N = (Na+ Ns) component species, Mx-Kx equilibrium-controlled complexed species, (My– Ky) equilibrium-controlled adsorbed species, Ky kinetic-controlled adsorbed species, (Mz– Kz) equilibrium-controlled ion-exchanged species, Kz kinetic-controlled ion exchanged species, (Mp– Kp) equilibrium-controlled potentially precipitated species, and Kp kinetic controlled precipitated species.  The transport module includes advection, dispersion/diffusion, and slight deformation.