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The program, examples, and manual can be
downloaded from the software download area.

Year: 1999
Version: 2.0

Authors: Attila Nemes, Marcel G. Schaap, and Feike J. Leij


UNSODA is a database of unsaturated soil hydraulic properties
  • Water retention
  • Hydraulic conductivity and soil water diffusivity
  • Basic soil properties (particle-size distribution, bulk density, organic matter content, etc.)
  • Additional information regarding the soil and the experimental procedures
It can be used to:
  • Store and edit data
  • Search for data sets based on user-defined query specifications
  • Write the contents of selected data sets to an output device
Mathematical models have become increasingly popular in the research and management of flow and transport processes in the subsurface environment. Because of improvements in computer software and hardware, the usefulness of numerical models hinges more and more on the availability of accurate input parameters. The unsaturated hydraulic functions are key input data in numerical models of vadose zone processes. These functions may be either measured directly, estimated indirectly through prediction from more easily measured data based upon quasi-empirical models, or approximated by using hydraulic data from similar soils.

UNSODA serves as a repository of data sets that can be used as a source of surrogate hydraulic data, or for the development and evaluation of indirect methods for estimating the unsaturated hydraulic properties.

UNSODA is written in Microsoft Access? database format (.mdb) for storage of data in tables. Information on operating UNSODA can be found in the file README.PDF.

Details on the collection process and the input variables are also discussed on pp. 11-15 and 21-27 of our more comprehensive manual UNSODA.PDF (which is based on the previous v1.0 DOS version of the database).

The software program Microsoft Access? is required to view and run the database file. This program is available in the Microsoft Office Professional Edition?.


The program and manual are available upon request from:

Technical contact:
Todd Skaggs
USDA-ARS U.S. Salinity Laboratory
450 W Big Springs Road
Riverside, CA 92507-4617

Tel: 951-369-4853
Fax: 951-342-4964