Case Study of Real-time Monitoring of Groundwater Levels and Rainfall Data for a Hillside Terrain Site Formation Works for Public Housing at Pok Fu Lam in Southern District, Hong Kong in Year 2023

A record-breaking extreme rainfall event happened in early September 2023 raised the public concern on the design safety of infrastructural works and geotechnical works to withstand the inclement weather. Real-time monitoring has become an effective tool nowadays to provide accurate and comprehensive information to record both the rainfall data and groundwater level for design review for civil engineering projects. This paper is to picturize the impact of extreme rainfall event on the groundwater table by case study on a hillside site formation project at Pok Fu Lam in Year 2023 via observations from the real-time rolling rainfall depth together with groundwater level. The groundwater levels have risen 3m to 18m from their long-term average level during the extreme rainfall event which the groundwater level rose with unprecedented magnitude especially for those located near existing natural drainage line identified from the aerial photo interpretation study. Superposition effect is also observed from two successive extreme rainfall events in September and October. Recommendations are then suggested to respond to the findings observed from the real-time monitoring information.