# GIS Approach for Expressing Structural Landforms: Forms, Elements, and Relationships
###### Abstract
The United States Geological Survey published FGDC Digital Cartographic Standard for Geologic Map Symbolization [32]. The Government of Western Australia Department of Mines, Industry Regulation and Safety published GSWA geologic map symbology structural line styles and symbols, with descriptions [33]. Technically, specific symbols were developed using the Representation tool in ArcGIS 10.0 for some landforms (e.g., alluvial fans, rock glaciers, and deltas) [34]. The symbols were created following embedded QGIS format style implement geomorphological mapping [35]. Many methods have been proposed for geomorphic mapping, such as the digital terrain analysis method [36], geomorphological combination legend method [30; 31], legend consisting of a several tiered nested hierarchy method [37], GIS and high-resolution digital data method [38], and the geomorphological information converted to digital information layer method [39]. As GIS has developed, the expressions of some specific forms, elements, and relationships in the fields of geology and geomorphology have been generated [40; 41; 42]. Currently, structural landform modeling is mainly based on the geometric forms of points, lines, and polygons of geological structural elements (folds, faults, etc.) to establish three-dimensional models of structural landforms. Based on the genetic classification of geomorphic elements (mountains, valleys, basins, etc. ), geometric coding of the basic types of geomorphic forms is carried out [43; 44; 45]. To study structural landforms such as mountains, valleys, basins, and other types of geomorphology, it is essential to begin with the definition of structural geomorphology. This involves abstracting the structural and geomorphological elements into a unified framework, constructing spatial structural and geomorphological objects manifested by structural phenomena, such as folds, faults, and rock masses formed by tectonics [46]. The relationships between various elements in structural geomorphology are mainly explored through spatial relationships between geological phenomena, such as folds, faults, and strata, as well as the tectonic deformation and geomorphic parameters (surface relief) of folds and faults [47; 48]. Quantitatively delineating the relationships between structural and geomorphic elements and establishing spatial correlations between these aspects using GIS topological frameworks is important. This approach precisely communicates the structural geological implications inherent in each distinct type of structural landform [30; 36]. This paper focuses on the phenomena of structural landforms in China. Based on traditional methods of structural geomorphology, this study combines surface morphological features to abstract structural landforms into geological and geomorphic elements, subsequently analyzing the characteristics and relationships of these elements. The structural landform elements and their relationships are abstracted into spatial objects and topological relationships. The approach proposed in this paper achieves the description and representation of the \"forms-elements-relationships\" framework of structural landforms from a GIS perspective.