## 2 Study Area and Data  
Huangshi Town is in the northeastern hilly region of Guangdong Province, under the jurisdiction of Longchuan County in Heyuan City. Geographical coordinates: East Longitude 115\({}^{\circ}\)10\({}^{\prime}\)14\({}^{\prime\prime}\)-115\({}^{\circ}\)18\({}^{\prime}\)07\({}^{\prime\prime}\), North Latitude 24\({}^{\circ}\)15\({}^{\prime}\)50\({}^{\prime\prime}\)-24\({}^{\circ}\)23\({}^{\prime}\)23\({}^{\prime\prime}\) (Figure 1). with a total area of 109.81 km\({}^{2}\), characterized by mountainous and hilly terrain, including approximately 10,700 mu of cultivated land and 140,000 mu of forest land.  
This geomorphology forms the basis of the regional hydrogeological conditions, while the complex geological environment, featuring a well-developed weathered crust and  
Figure 1: Digital elevation model of Huangshi Town.  
dense fault systems, further shapes the hydrological processes. In terms of hydrology, surface water and groundwater in Huangshi Town achieve bidirectional recharge through natural infiltration. Rainwater infiltration serves as the primary source of groundwater recharge, while during dry seasons, groundwater discharges into surface water in the form of diffuse flow or spring discharge. In the wet season, the rising river water levels recharge the groundwater system [15]. This recharge mechanism benefits from the fracture networks in the bedrock mountainous areas and the hilly terrain, with shallow fractured water providing an important water source for the region. However, the area is significantly influenced by extreme weather events, particularly during the \"Dragon Boat Water\" period, when short-duration intense rainfall (with 24-h rainfall exceeding 250 mm) and prolonged rainfall events occur frequently. Coupled with the complex topography and hydrogeological conditions, extreme rainfall can rapidly activate the groundwater dynamic system, leading to abrupt changes in the moisture content of slope bodies and greatly increasing the risk of geological hazards. Currently, geological hazards in Huangshi Town are predominantly collapses and landslides, with landslide disasters highly concentrated in areas with slope heights of 5-20 m (accounting for 90.79%) and slope gradients greater than 50\({}^{\circ}\) (accounting for 95.03%) [16].  
Moreover, human engineering activities, such as slope cutting for housing, construction of transportation infrastructure, and hillside cultivation, further exacerbate the potential for geological hazards [17]. However, current studies on geological hazard susceptibility in Huangshi Town mostly rely on static models and evaluate risks based solely on single rainfall indicators (e.g., annual average rainfall). These studies fail to adequately account for the coupled mechanisms between dynamic rainfall processes and geological hazards under extreme precipitation conditions and often neglect the combined effects of human activities and natural environmental factors on disaster occurrences [18].  
This study, based on the actual conditions in Huangshi Town, integrates multi-source data including topography, geology, meteorology, and human activities to systematically assess geological hazard risks. It aims to fill the research gap in disaster prediction under extreme rainfall conditions and to provide theoretical support and practical references for geological hazard prevention and control in subtropical hilly regions.