Characteristics of and Protection and Utilization Strategies for Cliff Landscapes in Mountain Cities: A Case Study of the Two Rivers and Four Banks Area in Chongqing

Objective As one of the important regional landscapes in mountain cities, cliffs play a significant role in urban imagery, social life, and related urban functions. In the new era, the status and role of cliff landscapes in cities have gradually changed. The sustainable development of cliff landscapes is of great significance to both mountain cities and cliffs themselves. However, there is a lack of systematic understanding of cliff landscapes within cities, and how to protect and utilize them is an urgent issue. Currently, research on cliff landscapes at home and abroad mainly focuses on the verification of their values, the utilization of their functions, and the exploration of engineering transformation techniques, while lacking an understanding of the overall distribution pattern of cliff landscapes and the interpretation of their spatial characteristics. Overall, the current research focuses more on cliff landscapes in special landforms than on those within the scope of urban construction in mountain cities. Therefore, conducting in-depth research on cliff landscapes in mountain cities will not only help gain a deeper understanding of the uniqueness of cliff landscapes in Chongqing, but also complement and improve the research on mountainous landscapes. It also has practical value for the future protection and utilization of cliff landscapes within cities. Methods Takeing the Two Rivers and Four Banks area in Chongqing featuring the concentrated distribution of cliff landscapes as an example, this research mainly refers to relevant discussions of Zhang Genshou and Wang Xudong. It considers natural or artificial landforms with a slope greater than 60° and a height of more than 10 meters as cliffs, with steep slopes with a height greater than 10 meters being also considered part of the cliffs. Firstly, based on the slope extraction and contour analysis methods, a spatial database is established on the ArcGIS platform to identify cliff landscapes. Secondly, through literature review and field investigation, the current status of cliff landscapes in the Two Rivers and Four Banks area is deeply investigated and discussed, and key information on the types, distribution, element composition, and utilization status of cliffs in the Two Rivers and Four Banks area is summarized. Results The research results indicate that the cliff landscapes in the Two Rivers and Four Banks area can be classified into three types based on their formation: natural cliffs, cliffs with human intervention, and artificial cliffs. Natural cliffs can be further divided into precipices, concave cliffs, and terraced cliffs based on their spatial forms. Cliffs with human intervention can be categorized into cliffs with construction thereon and cliffs with excavation therein. Artificial cliffs can be classified into artificially accumulated cliffs and artificially eroded cliffs. A total of 164 typical cliff landscape units are identified within the scope of the research, of which 88 ones are located on natural cliffs, 50 ones on cliffs with human intervention, and 26 ones on artificial cliffs. In terms of spatial distribution, they generally exhibit the two major characteristics of being located near mountains and water, and being adjacent to transportation routes. In terms of spatial function, they exhibit four utilization characteristics: Construction of urban defense systems based on the natural topography; construction of residential areas adapted to the mountainous terrain; development of a three-dimensional transportation system opened along the cliffs; development of various cliff lines for landscape exploration. The cultural value can be expressed from both spiritual and material perspectives. On one hand, steep cliffs are often regarded as a spiritual belief and emotional sustenance for people. On the other hand, the ancient buildings, inscriptions, and grottoes left on cliff landscape nodes demonstrate that cliff landscapes serve as an important carrier of cultural landscapes. As to habitat characteristics, natural cliffs have a rich variety of habitats, while the cliffs with human intervention and the artificial cliffs are relatively monotonous in terms of habitat type. Overall, cliff plants are dominated by spontaneous native plants, supplemented by artificially planted plants and alien invasive plants. In addition, the cliffs are of extremely high ecological value, and in different parts of the cliffs, due to differences in microhabitat conditions such as microclimate, water, light, heat, and substrate, the suitable plant species for growth also vary. Conclusion Based on the characteristics of cliff landscapes and the needs of urban development, this research identifies the protection and utilization elements of cliff landscapes, and initially puts forward three protection and utilization forms of cliff landscapes, which are mainly natural protection, cultural development and comprehensive utilization. The sustainable development strategy of cliff landscapes is proposed from three aspects: Transformation of cliff spatial functions, rational utilization of cliff resources, and management of cliff habitats. It is hoped that relevant results of this research can provide a strong scientific basis for the protection of cliff landscapes and the prevention of any further damage to such landscapes. And it is also hoped that these results can provide new perspectives and ideas for the development and utilization of cliff landscapes to maximize their economic, social and ecological benefits.