# GIS Approach for Expressing Structural Landforms: Forms, Elements, and Relationships
###### Abstract  
A structural landform is defined by its surface morphology, controlled by tectonics, lithology (arrangement and resistance), and folded structures, and demonstrated by the characteristics and relationships between geological and geomorphic elements. It is very important to use geographic information system (GIS) technology to accurately describe and express elements of structural landforms and their relationships. In this study, a GIS approach for expressing structural landforms, based on \"forms-elements-relationships\", was developed. The contributions of this paper are as follows: (1) Combined with the surface morphological characteristics, the structural landforms were abstracted into geological and geomorphic elements, and the characteristics and relationships of these elements were analyzed. (2) The elements of structural landforms and their relationships were abstracted into spatial objects and topological relationships. The spatial objects of the structural landform were designed based on the types and characteristics of structural landform elements. The topological relationships were developed based on the definition of the structural landform morphotype. (3) The structural landform markup language (SLML) method of \"forms-elements-relationships\" was created. (4) Two typical structural landforms, namely, Qixia Mountain and Gaoli Mountain, were used as examples to verify the feasibility and effectiveness of the GIS approach for expressing structural landforms. This paper describes and expresses the \"forms-elements-relationships\" of structural landforms from the perspective of GIS, which is expected to promote the joint development of structural geomorphology and GIS. GIS; structural landform; forms; elements; relationships +
Footnote †: journal: Applied sciences  
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Footnote 0: _Applied Sciences_  
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Footnote 0: _Applied Sciences_  
volcanic landforms [10], karst landforms [11], and granitic landforms [12]. Structural landforms are geomorphic forms that are controlled by tectonic effects, are determined by the interactions of geological dynamics, and can reflect structural characteristics [3; 4]. The main research foci of structural landforms are the topographic form (anticlinal mountains, synclinal mountains, fault-block mountains, etc. ), which geological and geomorphic elements (anticline, syncline, ridge, valley, etc.) constitute these topographic forms, and the characteristics of elements and their spatial interrelations. The forms, elements, and relationships of structural landforms are the main research foci of structural geomorphology. To determine the forms of structural landforms, pattern [13; 14], morphology [15; 16], sedimentary correlation [17; 18], and chronological analyses [19; 20] are used to evaluate the structural landforms and classify their different types. Physical and mathematical equations are used to describe the three-dimensional morphological characteristics and evolution of surfaces [21; 22; 23; 24]. As computer, geographic information, and remote sensing sciences mature, studies of structural landforms are becoming more focused on information and quantification [24; 25; 26]. The extraction of geological and geomorphic elements from structural landforms and the description of the relationships between the elements have been developed [8; 27]. Geographic information system (GIS) geospatial tools are employed for the analysis of structural landform relationships. These specifically focus on the interrelationship between structural elements and geomorphologic features, such as basins and valleys, to unveil the spatial interrelation of elements within structural landforms [28; 29; 30; 31]. This analysis makes it possible to express the forms, elements, and relationships of structural landforms through GIS. There are already numerous standards, techniques, and methods for geomorphological mapping using GIS. In some countries, guidelines and systems are available for geomorphological mapping.