Analysis of rainfall trends in period 1982-2019 at Tan Son Hoa Meteorological Station, Ho Chi Minh City

Abstract

The impacts of urbanization and climate change are drastically changing rainfall patterns in urban areas that exacerbate water-related risks such as inundation/flooding, drought, and environmental pollution. Predicting rainfall trends provides useful information to proactively mitigate the impact of water-related risks. This research aims to quantitatively identify the changes of rainfall patterns in durations of 15, 30, 45, 60, 90, 120, 180, and 360 mins covering from 1982 to 2019 at Tan Son Hoa meteorological station located in Ho Chi Minh City. In the period 1982-2019, the observed rainfall data showed 579 rainfall events with a total volume higher than 30mm (average of about 15 events/year), and extreme rainfall events have occurred quite frequently since 2016. Mann- Kendall's nonparametric test and Sen's slope estimator showed that rainfall trend strongly increased (statistical significance) for the short durations of 15, 30, 45, 60, 90 mins and increased moderately (statistical significance) for 120 mins duration but slightly increased for the durations of 180 and 360 mins and it was not statistically significant. The trend of rainfall in the duration of 45 mins increased the most with an average rate of about 0.7 mm/year. An increase in short-duration rainfall can exacerbate urban flooding due to overloaded drainage systems. The findings of this research could support urban flood risk management and other water-related environmental issues in Ho Chi Minh City.