MOC3D is a general-purpose computer model developed by the U.S. Geological Survey (USGS) for simulation of three-dimensional solute transport in ground water (Konikow and others, 1996). The model is an update to the widely used USGS two-dimensional solute-transport model (MOC) and is implemented as an optional “package” for the ground-water flow model MODFLOW (Harbaugh and McDonald, 1996). Directly coupling the time-tested MOC transport algorithms with the widely used MODFLOW program makes MOC3D a powerful tool for simulation of solute transport in ground water in many hydrogeologic settings. The model simulates transport processes that include:
- Advection - Transport of dissolved solutes at the same rate as the average ground-water flow velocity.
- Diffusion - Spreading of solute from areas of high concentration to areas of low concentration, caused by “random” molecular motion
- Dispersion - Diffusion-like spreading of solute that is caused primarily by spatial variability in aquifer properties, which results in spatial variability in transport velocity.
- Retardation - Reduction in the apparent solute velocity, compared to the ground-water velocity, caused by linear equilibrium sorption on aquifer materials.
- Decay - Disappearance of solute caused by reactions such as radioactive decay or biodegradation that are proportional to concentration.
- Growth - Creation (or disappearance) of solute mass caused by reactions that proceed independent of the solute concentration, such as some cases of biodegradation
- Double-porosity exchange - rate-limited exchange of solute mass between mobile and immobile zones; for example, between fractures and the rock matrix.
Goode, D.J., 1999, Simulating contaminant attenuation, double-porosity exchange, and water age in aquifers using MOC3D: U.S. Geological Survey Fact Sheet 1999–0086, 4 p., https://pubs.er.usgs.gov/publication/fs08699.
ISSN: 2327-6932 (online)
Table of Contents
- MOC3D - A General-Purpose Solute-Transport Model
- Attenuation of Contaminants in Aquifers Having Spatially VAriable Geochemistry
- Double-Porosity Exchange: Matrix Diffusion in Fractured Rock
- Effects of Dispersion on Ground-Water Age
- Model Compatibility and Availability
- References Cited
Additional publication details
|Publication Subtype||USGS Numbered Series|
|Title||Simulating contaminant attenuation, double-porosity exchange, and water age in aquifers using MOC3D|
|Series title||Fact Sheet|
|Publisher||U.S. Geological Survey|
|Publisher location||Reston, VA|
|Contributing office(s)||Pennsylvania Water Science Center|