Investigating Historical Storm Surge Occurrences in the Philippines from Tide Gauge Observations

Tropical cyclones (TCs) frequently affect the Philippines, making its coastal areas highly vulnerable to TC-induced hazards such as storm surges. As an archipelagic country with an extensive and complex coastline, local variations in coastal characteristics can influence surge magnitude and extent. Despite this, most of the previous studies have focused on individual extreme events or model-based simulations of specific TCs, with few directed toward systematically compiling storm surge histories from instrumental records across the entire country. This study addresses this gap by investigating historical storm surge events (SSE) in the Philippines using tide gauge observations from 1947 to 2024. A variable annual threshold was applied to the residual sea level derived from tide gauge data, identifying 133 SSEs across multiple coastal locations. The identified SSE exceeding 1 m above mean sea level, occurred in areas characterized by shallow and wide continental shelves that amplify surge response, which included the stations located along the east, north, and west coasts of the country. In contrast, SSEs were largely absent in the southern part of the country (Mindanao), likely due to its proximity to the equator where the weak Coriolis force limits TC intensification. Five selected TC case studies of high storm tides further illustrated that surge magnitude depends not only on TC proximity but also on coastal geometry and bathymetry. The resulting database enhances understanding of storm surge variability across the Philippine coasts and provides a foundation for improving localized SSE forecasting, hazard mapping, and risk assessment frameworks.