<資料・研究ノート>衛星写真判読による小縮尺地形分類図の試作 : ジャワ島東部の場合

Abstract

When one wants to research land or water resources in Southeast Asia, one meets difficulties in using topographical maps or aerial photographs, because security considerations make governments worry of mapping operations. Therefore, instead of using aerial photographs, the writer has attempted to use photographs taken by ERTS which have no restrictions their use. An area of the eastern part of Java was selected partly because when photographs were taken, there were no clouds, and partly because many active volcanoes, the largest alluvial plain in Java, and a big city (Suravaja) are included in the photograph. Utilizing these photographs, the writer has classified the area geomorphologically and found the following facts. (1) When one wants to classify land geomorphologically, the 7th band, i. e. near infrared, photographs are most suitable. In these photographs, water surfaces : rivers, lakes, seas, etc. appear black, and marshes as light black; on the other hand, dry areas : the tops of volcanoes and natural levees, appear white. Utilizing this color contrast, we can classify the area. (2) Utilizing mainly photographs by ERTS, topographical maps or geological maps as supplements, the writer could classify the area into the following geomorphological elements : volcano, hill, terrace and alluvial plain. (3) Volcanoes could be classified as follows : crater or caldera, volcanoes with large relief energy and those with small relief energy, and piedmont gentle slopes. The walls of calderas are shown very cleary in the photographs and one can measure their diameter. Furthermore, one can see the central cone in calderas. A volcano which has large relief energy is shown as white due to the fact that the ground water level is deep; on the other hand a volcano which has small relief energy is a light black color. And one can observe the size and number of valleys. Based on the state of the valley, one can divide the volcanoes into young volcanoes and old volcanoes. Furthermore, we could see the relationship between erosion on the steep slopes of mountains and deposition at the foot of these mountains. Using the present state of erosion and deposition, one can estimate erosion and deposition which will occur in the near future, too. (4) The hills and terraces are classified as follows : tertiary hills, limestone terraces, and terraces. We could trace the boundary of the limestone terrace due to its special relief pattern against the terrace. (5) The alluvial plain is divided into two parts : natural levees and back-swamp, and delta areas. Furthermore, we could estimate agents of back-swamp formation by photo interpretation.