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UNSODA 2.0: Unsaturated Soil Hydraulic Database. Database and program for indirect methods of estimating unsaturated hydraulic properties

This database contains measured soil water retention, hydraulic conductivity, and water diffusivity data, as well as pedological information of some 790 soil samples from around the world.

Quantifying water flow and chemical transport in the vadose zone typically requires knowledge of the unsaturated soil hydraulic properties. The UNsaturated SOil hydraulic DAtabase (UNSODA) was developed to provide a source of unsaturated hydraulic data and some other soil properties for practitioners and researchers. A first MS-DOS version of the database was released in 1996. It has been applied in numerous studies. In this paper, we describe the second version (UNSODA V2.0) for use with Microsoft Access-97®1. The format and structure of the new database have been modified to provide additional and more convenient options for data searches, to provide compatibility with other programs for easy loading and downloading of data, and to allow users to customise the contents and look of graphical output. This paper reviews the structure and contents of the database as well as the operations that can be performed on the different data types in UNSODA V2.0. The use and application of the new database are illustrated with two examples. The retrieval of data is briefly illustrated, followed by a more detailed example regarding the interpolation of soil particle-size distribution data obtained according to different national definitions of particle-size classes. The interpolation procedure, which is based on finding similar particle-size distribution curves from a large European data set, also performed well for soils that originate from other geographical areas.

Dataset Info

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Nemes, Attila
Schaap, Marcel
Leij, Feike J.
Wösten, J. Henk M.
Product Type
Spatial / Geographical Coverage Location
Temporal Coverage
US Salinity Laboratory - ARS - USDA
Contact Name
Skaggs, Todd
Contact Email
Public Access Level
Related Article

Nemes, A., Schaap, M., Leij, F., & Wösten, J. (2001). Description of the unsaturated soil hydraulic database UNSODA version 2.0. Journal Of Hydrology, 251(3-4), 151-162.  

AgID: 10113/60505

Børgesen, C. D., Jacobsen, O. H., Hansen, S., & Schaap, M. G. (2006). Soil hydraulic properties near saturation, an improved conductivity model. Journal of Hydrology, 324(1), 40-50. 

AgID: 10113/2455
Funding Source(s)
Agricultural Research Service
Dataset DOI (digital object identifier)
Program Code
005:037 - Department of Agriculture - Research and Education
Bureau Code
005:18 - Agricultural Research Service
Modified Date
Release Date
Ag Data Commons Keywords: 
  • Agroecosystems & Environment
  • Agroecosystems & Environment
  • Soil
ISO Topic(s):