Objective Geological hazard investigation and evaluation based on slope units have emerged as a crucial approach in China in recent years for detailed surveys in high−incidence and frequent−occurrence areas. The rational delineation of the number of slope units holds significant importance for subsequent hazard investigation, evaluation, and routine management.

Methods This study proposes an integrated slope unit delineation scheme based on an analysis of the maximum and ideal number of inhabited slopes that can be effectively investigated and managed by survey administrators, combined with an improved curvature watershed method. Subsequently, 8 and 7 secondary evaluation factors were selected for rock slopes and soil slopes, respectively. A qualitative−semi−quantitative evaluation model was employed to explore a geological hazard susceptibility evaluation method basedon slope units.

Results Using the integrated slope unit delineation scheme, 14480 slope units were identified in Anju District, Suining City, including 13,071 inhabited slope units, 897 uninhabited slope units, and 512 flat land units. Applying an Analytic Hierarchy Process (AHP)−based qualitative−semi−quantitative evaluation model, susceptibility was assessed for each slope unit. Results indicate 196 medium−susceptibility units and 14284 low−susceptibility units, accounting for 1.24% and 98.76% of the total area, respectively.

Conclusions When conducting geological hazard susceptibility evaluations based on slope units, it is essential to balance the subjectivity of survey management capacity with the objectivity of theoretical models, ensuring evaluation outcomes better serve slope hazard prevention at the county level. The AHP−based qualitative−semi−quantitative model using slope units outperforms grid−based information value models in result quality. This method is suitable for county−level 1∶10000 slope unit geological hazard evaluations.