The purpose of this paper is to express geomorphic characteristics of Shikoku Island, especially the effects of geological structures on landforms, by means of the statistical analysis of morphometric values obtained by the numerical computation using Digital Terrain Model. To Shikoku Island, where geologic provinces distribute zonally, the application of the analysis is relatively easy.
In addition to altitude, relief energy and “dispersion of altitude” per unit area, curvature, gradient, and direction of maximum gradient were computed as parameters which express local geomorphic characteristics. Figures showing distributions of these values in both space and frequency give an outline of the geomorphic characteristics of Shikoku Island.
The curve of altitude-frequency distribution shows three points of gradient change at 700_??_800m, at about 1, 200m and at 1, 500_??_ 1, 600m. “Geomorphic history” (Sakaguchi, 1964) of Shikoku Island, therefore, can possibly be divided into four stages by these points.
Some statistical variables, such as standerd deviation, skewness and kurtosis, power, and entropy, were computed from the altitude-frequency distribution to express general geomorphic characteristics in some regions. Standerd deviation and power indicate “dispersion of altitude” and degree of flat surface expanse, respectively. Entropy indicates degree of general relief in the region.
The difference in geomorphic characteristics due to the difference in geology and in the amount of tectonic movement could be quantitatively expressed by these statistical variables.
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