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UNSATCHEM - Software Package for Simulating Water, Heat, Carbon Dioxide and Solute Movement in One-Dimensional Variably Saturated Media
Entry ID: USDA_ARS_UNSATCHEM

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Summary

Abstract: UNSATCHEM is a software package for simulating water, heat, carbon dioxide and solute movement in one-dimensional variably saturated media. The software consists of the UNSCHEM (version 2.0) computer program, and the UNSATCH interactive graphics-based user interface. The UNSCHEM program numerically solves the Richards' equation for variably-saturated water flow and convection-dispersion type ... equations for heat, carbon dioxide and solute transport. The flow equation incorporates a sink term to account for water uptake by plant roots. The heat transport equation considers transport due to conduction and convection with flowing water. Diffusion in both liquid and gas phases and convection in the liquid phase are considered as CO2 transport mechanisms. The CO2 production model is described. The major variables of the chemical system are Ca, Mg, Na, K, SO4, Cl, NO3, H4SiO4, alkalinity, and CO2. The model accounts for equilibrium chemical reactions between these components such as complexation, cation exchange and precipitation-dissolution. For the precipitation-dissolution of calcite and dissolution of dolomite, either equilibrium or multicomponent kinetic expressions are used which include both forward and back reactions. Other dissolution-precipitation reactions considered include gypsum, hydromagnesite, nesquehonite, and sepiolite. Since the ionic strength of soil solutions can vary considerably with time and space and often reach high values, both modified Debye-Huckel and Pitzer expressions were incorporated into the model as options to calculate single ion activities.

The program may be used to analyze water and solute movement in unsaturated, partially saturated, or fully saturated porous media. The flow region may be composed of nonuniform soils. Flow and transport can occur in the vertical, horizontal, or a generally inclined direction. The water flow part of the model can deal with prescribed head and flux boundaries, boundaries controlled by atmospheric conditions, as well as free drainage boundary conditions. The governing flow and transport equations are solved numerically using finite differences and Galerkin-type linear finite element schemes, respectively.

This report serves as both a user manual and reference document. Detailed instructions are given for data input preparation. A graphics-based user interface, UNSATCH, for data preparation and graphical output display in the MS Windows environment is described in the second part of the manual.

[Summary provided by the USDA.]

Description: Access the UNSATCHEM software package (registration required).

Service Citation

Originators: USDA-ARS U.S. Salinity Laboratory
Title: UNSATCHEM - Software Package for Simulating Water, Heat, Carbon Dioxide and Solute Movement in One-Dimensional Variably Saturated Media
Provider: USDA-ARS U.S. Salinity Laboratory
Edition: 2.0
URL: http://www.ars.usda.gov/Services/docs.htm?docid=8966

Service Keywords

DATA ANALYSIS AND VISUALIZATION >STATISTICAL APPLICATIONS

MODELS >REGULATORY MODELS

Science Keywords

AGRICULTURE >SOILS >SOIL MOISTURE/WATER CONTENT

TERRESTRIAL HYDROSPHERE >GROUND WATER >GROUND WATER DISCHARGE/FLOW

ISO Topic Category

FARMING
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
ENVIRONMENT
GEOSCIENTIFIC INFORMATION

Access Constraints User registration is required before downloading the software package.

Ancillary Keywords

Models
Solute Movement

Service Provider

USDA/ARS/USSL > U.S. Salinity Laboratory, Agricultural Research Service, U. S. Department of Agriculture

Service Organization URL: http://www.ars.usda.gov/pwa/riverside/gebjsl

Service Provider Personnel
Name: DONALD LOUIS SUAREZ Phone: (951) 369-4816 Fax: (951) 342-4962 Email: dsuarez at ussl.ars.usda.gov Contact Address: George E. Brown, Jr. Salinity Laboratory 450 West Big Springs Road USDA, ARS City: Riverside Province or State: CA Postal Code: 92507-4617 Country: USA

Personnel

DONALD LOUIS SUAREZ
Role: TECHNICAL CONTACT
Phone: (951) 369-4816
Fax: (951) 342-4962
Email: dsuarez at ussl.ars.usda.gov
Contact Address:
George E. Brown, Jr. Salinity Laboratory
450 West Big Springs Road
USDA, ARS
City: Riverside
Province or State: CA
Postal Code: 92507-4617
Country: USA

TYLER B. STEVENS
Role: SERF AUTHOR
Phone: (301) 614-6898
Fax: 301-614-5268
Email: Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA

Creation and Review Dates

SERF Creation Date: 2011-05-11
SERF Last Revision Date: 2011-05-12

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