The main data used and referenced include:

1) Remote sensing image data: TM images of around 1990's and ETM images of around 2000's nationwide

2) Historical geomorphic maps: 15 published 1 million geomorphic maps, two sets of 1:4 million national geomorphic maps, and sketches of 500000 or 1 million geomorphic maps from various provinces and cities across the country

3) Basic geographic data: National 1:250000 basic geographic data and 250000 DEM data

4) Geological data: 1:500000 geological maps nationwide

5) Related thematic maps: land use maps, vegetation maps, land resource maps, etc

The interpretation method adopts an ARCGIS based human-machine interaction method and follows a hierarchical interpretation sequence:

The first layer: plains and mountains

The second layer: basic geomorphic types (28 types)

The third layer: 10 genetic types

Fourth layer: secondary genetic types

Fifth layer: Classification of morphological differences

Level 6: Classification of secondary morphological differences

The seventh layer: slope, aspect, and their combination to determine the degree of inclination or slope of the terrain

The eighth layer: the type of geomorphic material determined by material composition or lithology

9th layer: Merge 1-7 layers of patches. There are a total of 441 types of landforms and their codes

After precise correction