# Landslide Susceptibility Assessment in Hong Kong with Consideration of Spatio-Temporal Consistency
## 2 Study Area and Dataset  
### Study Area  
Hong Kong is located in the south of China, east of the Pearl River Estuary, with longitude and latitude ranging from 22.15\({}^{\circ}\) to 22.56\({}^{\circ}\) N and 113.84\({}^{\circ}\) to 114.44\({}^{\circ}\) E (as shown in Figure 1). It neighbors Shenzhen toward the north, faces Macao across the sea toward the west, connects to the Zhuhai Wanshan Archipelago toward the south, and faces the South China Sea toward the east. Hong Kong, Macao, and Guangdong jointly constitute the Guangdong-Hong Kong-Macao Greater Bay Area. The elevation range of the research area is 0-925 m, and the slope range is 0-60\({}^{\circ}\) (with an average slope of 12.12\({}^{\circ}\)). The terrain is mainly characterized by low-altitude mountainous areas with medium and small fluctuations, underwater deltas, and low-altitude hills. The vegetation coverage is generally high. Hong Kong has a subtropical monsoon climate with long summers and short winters. Summers are hot and rainy, while winters are warm and dry with less rain. This climate type makes Hong Kong's temperature pleasant throughout the year, but there are also significant seasonal differences. Summer temperatures usually range from 26 to 30 \({}^{\circ}\)C, and Hong Kong experiences frequent and sometimes heavy rainfall during this season, accompanied by extreme weather such as typhoons. Winters (from December to February) are relatively cool, with temperatures generally ranging from 10 to 20 \({}^{\circ}\)C. It rarely drops below 5 \({}^{\circ}\)C, and the weather is relatively dry. Hong Kong is also influenced by a marine climate, resulting in high humidity throughout the year, with an average relative humidity of approximately 78%. Additionally, Hong Kong's geographic location in a typhoon-prone area exposes it to potential typhoon impacts during the summer and autumn seasons. The climatic characteristics of Hong Kong determine that the recharge of groundwater mainly comes from atmospheric precipitation. A large amount of rainwater infiltrates through the surface and underground runoff, providing a rich source of recharge for groundwater. The stratigraphic lithology includes Quaternary deposits, Tertiary red clay sandstone and fan-shaped sandstone, as well as Permian granite and andesite [36]. Located in the hilly region of the southeast coast, Hong Kong has complex geological conditions with numerous mountains and hills. Coupled with the influence of monsoon winds, frequent summer rainstorms provide conditions for the occurrence of landslide disasters. As one of the most densely populated regions globally, Hong Kong faces a scarcity of land resources, leading to the construction of residential buildings and public infrastructure, often in hilly areas. This, in turn, increases the risk of landslide disasters. Landslides in Hong Kong are characterized by frequent occurrence, destructiveness, and unpredictability. Once a landslide occurs, it not only causes casualties and property damage but also severely impacts local transportation, communication, and other infrastructure. Typical landslide-prone areas include the hills of the New Territories in Hong Kong, as well as some residential areas and public facilities near mountainous regions. Take the landslide disaster on Po Shan Road as an example. On 18 June 1972, after continuous heavy rainstorms hit Hong Kong Island, large-scale landslides occurred consecutively on the slopes behind Po Shan Road, resulting in a significant landslide deposit and causing a severe accident with 67 fatalities, 20 injuries, the disruption of roads at the lower edge of the landslide, and the complete destruction of two high-rise buildings. The economic losses amounted to tens of millions of Hong Kong dollars.