Background Geological hazard risk refers to the probability and severity of losses suffered by elements at risk due to geological hazards in a certain area and period. In order to obtain high-precision landslide geological hazard risk background data, the author proposed a landslide geological hazard risk assessment method suitable for the township (street) regional scale. Taking Chengguan town of Shiquan county, Shaanxi province as an example, the author noted that this area is located in the high-incidence zone of landslides in the Qinba Mountains, with high density of geological disasters and hidden dangers. The constructed assessment model can be migrated to areas with similar geological backgrounds.

Methods The study took the slope as the assessment unit and constructed a full-process assessment method integrating multiple conditional models: the comprehensive index method was used to evaluate the susceptibility. The hazard was evaluated through three conditional assumptions of the extreme rainfall hypothesis, effective rainfall, and slope unit stability. The vulnerability was evaluated by weighted summation of quantitative indicators of elements at risk. Finally, the risk was evaluated by synthesizing the hazard and vulnerability.

Results The results show that in the susceptibility assessment results, affected by the weak metamorphic rock strata and strong human activities, the hilly gentle slope zone in the middle has become a high-susceptibility area (accounting for 58.2%), and the low-disturbance mid-mountain area had the lowest susceptibility. The spatial distribution of historical hidden danger points verified the rationality of the assessment results. In the hazard assessment, the effective rainfall model and the extreme rainfall hypothesis model revealed the differences in regional geological hazards under different rainfall conditions. The effective rainfall model based on historical disaster occurrence events was more conservative than the regional multi-year extreme rainfall model, while the slope stability model more significantly revealed the spatial hazard differences of slope units. In the vulnerability assessment, through the analysis of the attributes of elements at risk, the consistency of the spatial distribution of personnel and building vulnerability was verified, and the road vulnerability assessment results were consistent with the spatial pattern of the road network. The comprehensive risk assessment divided 581 slope units into extremely high, high, moderate, and low risks. Field verification showed that the identification accuracy of high-risk slope units reaches 100%, and there were some deviations between moderate and low-risk slope units and the model results.

Conclusions In summary, the geological hazard risk assessment method based on slope units proposed in this study may provide both a reliable solution for higher-precision landslide geological hazard risk assessment at the township (street) regional scale and technical support for regional geological hazard prevention and control.