TENNESSEE VALLEY AUTHORITY DIVISION OF WATER CONTROL PLANNING HYDRAULIC DATA BRANCH |
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| Authors: | G E LALIBERTE |
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| Institution: | 1. Funda?ao Centro Tecnológico de Minas Gerais , Brazil;2. Federal University of Rio Grande do Sul , Brazil |
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| Abstract: | ABSTRACT Statistical surveys of vegetative cover, soils, and other measures, called hydrologic condition surveys, have been collected by the Tennessee Valley Authority for several years. Attempts to assure that sufficient data were collected for future studies resulted in a total of 53 variables being defined. Because the exact nature of these future studies was unknown it was difficult to reduce the number of variables despite the fact it was known that some of the variables were highly interrelated. The technique of factor analysis provided a means for determining the number of independent measures available in the survey data. Factor analysis will establish a reduced set of independent, or orthogonal, factors that will represent the original data. The factors can be used as guides to reduce the set of original variables. In the study, these factors were used to indicate the total number of variables that could be justified in a survey, to indicate the number of independent measures available within survey groupings, and to identify variables that were highly interrelated. This information and other criteria were used to reduce the number of variables measured and to establish a new survey that should contain primarily independent measures of hydrologic conditions. Equally important, however, this study provided an opportunity to review systematically and improve a survey procedure that had been developed piecemeal without comprehensive objectives to serve as guidelines. |
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