Geological Hazard Susceptibility Assessment Based on Combined Weighting Method: A Case Study of Xi'an City

Geological hazards severely constrain urban construction planning and economic development, particularly for large and medium-sized cities. Xi'an City is located in the transitional zone between the Guanzhong Plain and the Qinling Mountains, characterized by complex geological conditions and frequent occurrence of various geological hazards, posing serious threats to regional economic development and the safety of residents' lives and property. Currently, diverse methods and models exist for geological hazard susceptibility assessment. Selecting appropriate evaluation models and assessment factors to conduct geological hazard susceptibility evaluation plays a crucial role in geological hazard risk management and economic development promotion in Xi'an City. Taking geological hazards throughout Xi'an City as the research object, this study analyzed the formation conditions and influencing factors of geological hazards. Via Spearman correlation analysis, appropriate evaluation indicators were selected, and a geological hazard susceptibility assessment system was constructed through the comprehensive application of the combined weighting method and information value model. The main research findings are as follows: (1) A total of 787 geological hazards (hidden danger points) have developed in Xi'an City, predominantly landslides (435 occurrences) and collapses (304 occurrences), distributed in loess landform areas and the Qinling mountainous region, while ground subsidence and ground fissures are mainly distributed in alluvial plain areas; (2) Twelve factors including slope gradient, slope aspect, and surface relief were selected as susceptibility evaluation indicators. The analytic hierarchy process was employed to determine subjective weights, the entropy weight method was used to calculate objective weights, and the distance function method was utilized to combine the two types of weights; (3) Four information value models were established: unweighted, subjective weighted, objective weighted, and combined weighted models. Through verification via hazard point density and ROC curves, the combined weighting information value model demonstrated the highest evaluation accuracy (AUC value of 0.872); (4) The combined weighting information value model was employed to assess geological hazard susceptibility in Xi'an City, resulting in classification into high susceptibility areas (1,305.36 km², accounting for 12.31%), moderate susceptibility areas (1,980.96 km², accounting for 18.68%), low susceptibility areas (835.48 km², accounting for 7.88%), and non-susceptible areas (6,485.72 km², accounting for 61.14%). The study demonstrates that the combined weighting method can overcome the limitations of single weighting approaches, and the evaluation results better conform to the distribution patterns of geological hazards in the study area, providing a scientific basis for geological hazard prevention and control in Xi'an City.