Document Type

Dissertation - Open Access

Award Date

1972

Degree Name

Doctor of Philosophy (PhD)

Department

Agronomy

First Advisor

Fred C. Westin

Abstract

A physiographic terrain analysis study using the principles of airphoto interpretation was made: (1) to determine the internal homogeneity of airphoto interpreted mapping units, (2) to determine the variability in characteristics among different occurrences of the same mapping unit, and (3) to determine if the units differentiated were sufficiently different to warrant discrimination. The study was conducted in Sedgewick County, Colorado. The study area was comprised of four distinctly different land forms [sic]: a major river and its associated floodplain and terraces; a level to nearly level loamy upland plain; a level to sloping sandy upland plain; and steeply sloping, sandy and gravelly rough broken lands. Five soil characteristics, namely, soil drainage, soil depth, surface soil texture, subsoil texture and water-holding capacity; two soil related characteristics, namely, parent material and slope; and three use classifications, namely, range site group, land capability class, and engineering class of both the surface and subsoil were used to evaluate the predictive value of airphoto interpreted mapping units for moderately extensive land use. A detailed standard soil survey was used to determine the definitive characteristics of the airphoto interpreted mapping units. Internal homogeneity values ranged from 42 to 100 percent over all mapping units and all characteristics. Results obtained showed that of 86 total mapping units studied, 82 or 95%, 76 or 88%, 72 or 84%, 58 or 67%, 67 or 77%, 5 7 or 66%, 8 3 or 9 6%, 7 6 or 88%, 71 or 82%, 65 or 75% and 52 or 60% were> 75% internally homogeneous for parent material, slope, soil drainage class, water-holding capacity, surface soil texture, subsoil texture, soil depth, range site group, land capability class, and unified engineering classification of the surface and subsoil, respectively. Airphoto interpretation was considered successful for providing relatively homogeneous units with respect to parent material, slope, soil drainage class, soil depth, range site group, and land capability class. Homogeneity values for texture were based on actual textural class which resulted in lower homogeneity values for texture, water-holding capacity and engineering classification. Variability in characteristics among different occurrences of the same mapping unit was evaluated by grouping similar mapping units into what were termed land facets. Sixteen land facets were developed. Of 143 comparisons made, 13 exceeded coefficients of variability of >20 percent; with the highest being 24 percent. The larger coefficients of variability were associated with subsoil texture, water-holding capacity, and engineering classification of the subsoil Results obtained indicated that variability in land facets for different characteristics varied considerably among different land forms. Low lying terraces or bottomlands consistently showed greater variability for nearly all characteristics. Transition zones between sloping hummocky areas and level areas on the sandy uplands also showed larger variability in all characteristics. Coefficients of variability were considered acceptable for defining land facets which are sufficiently similar that one can make rather precise statements about their characteristics. The results indicated that a high degree of success was achieved with respect to grouping mapping units having similar definitive characteristics. Eighty two of 85 mapping units were placed into the correct land facet. All land facets except two were sufficiently different in characteristics to warrant discrimination. In general, the results indicate that there is a consistent relationship within a mapping unit in the degree of homogeneity with respect to parent material, soil drainage, soil depth, slope, range site group and land capability class. From this study it was concluded that airphoto interpretation was successful for delineating landscape units that are sufficiently homogeneous with respect to parent material, slope, soil drainage class, iii soil depth, range site group and land capability classification to have predictive value for moderately extensive land use. And except for two land facets, one occurring on low lying terraces, and the other in the sandy uplands, a moderate to high amount of success was achieved with respect to delineating units that are sufficiently homogeneous for soil texture.

Library of Congress Subject Headings

Photographic surveying
Land use -- classification
Aerial photography

Format

application/pdf

Number of Pages

112

Publisher

South Dakota State University

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