METHOD AND PRACTICE OF GROUND SUBSTRATE STRUCTURE SURVEY BASED ON GEOMORPHIC DIVISION: A Case Study of Changchun Region

Ground substrate is the basic content of natural resources survey, but there is not yet a unified working guideline on how to carry out the work. Based on the ground substrate survey in Changchun region, the paper proposes the method of ground substrate structure survey based on geomorphic unit division, and systematically summarizes the spatial structure characteristics of ground substrate in the area. The results show that the ground substrate at the depth of 0-20 cm below surface is mainly soil and complemented by mud in the valley alluvial plain, piedmont platform and intermountain basin valley area, while mainly rock and supplemented by gravel in low mountain and hilly area. At the depth of 0-5 m below surface, the typical structure of ground substrate in floodplain and first terrace can be divided into two types, i.e., loam+sandy soil and loam+clayey loam+clayey loam, with grayish black loam+yellow brown clayey loam+yellow clayey loam in second terrace, piedmont platform and intermountain basin valley area, and loam+sandy soil(or skeleton soil)+rock in low mountain and hilly area. At the depth of 0-50 m below surface, the typical structure of ground substrate in floodplain and first terrace is loam+sandy soil+rock, with clayey loam+sandy soil+rock in second terrace, and clayey loam+rock in piedmont platform, and loam+sandy soil (or skeleton soil)+rock in low mountain and hilly area. The ground substrate structure in intermountain basin valley area is basically the same as that in second terrace or piedmont platform.