Comparison and Applications of the Thornthwaite Moisture Index Using GIS

Austin H. Olaiz, Sai H. Singhar, Jeffry D. Vann, Sandra Houston

Research output: Contribution to journalConference articlepeer-review

7 Scopus citations


Comparison of four different TMI computational methods are made using the National Oceanic and Atmospheric Administration's (NOAA) 30-year (1981-2010) climate normal for the U.S., are presented. Comparisons of the four TMI contour maps and evaluation of specific locations within Texas reveal discrepancies between each method. Contour maps of the continental U.S. are presented for the TMI-1955, TMI-1992, and TMI-2006, and analyzed along with the TMI-1948 contour from Thornthwaite (1948) using a geographic information system (GIS) platform. The GIS platform was developed as a tool for determining the TMI-1955, TMI-1992, and TMI-2006 at any desired location within the U.S. Comparison of various TMI computational methods indicates that the adoption of the TMI-2006 method most closely matches the original moisture balance approach of the TMI-1948 method, as was intended by its developers; however, caution should be taken when implementing TMI-based climate analysis in geotechnical applications given variability in methods and sensitivity to selected input data.

Original languageEnglish (US)
Pages (from-to)280-289
Number of pages10
JournalGeotechnical Special Publication
Issue numberGSP 302
StatePublished - Jan 1 2018
Event2nd Pan-American Conference on Unsaturated Soils: Applications, PanAm-UNSAT 2017 - Dallas, United States
Duration: Nov 12 2017Nov 15 2017

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Architecture
  • Building and Construction
  • Geotechnical Engineering and Engineering Geology


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