Spatiotemporal Trend Analysis of Precipitation Extremes in Ho Chi Minh City, Vietnam During 1980-2017

In this study, the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980-2017 was analyzed based on several core extreme precipitation indices (Rx1day, Rx5day, CDD, CWD, R20mm, R25mm, R95p, and SDII). The non-parametric Mann-Kendall and Sen's slope methods were used to compute the statistical strength, stability, and magnitude of trends in annual rainfall, as well as the extreme precipitation indices. We found that 64% of the stations had statistically significant upward trends in yearly rainfall, with high magnitudes frequently observed in the northern and southern regions of the city. For the extreme precipitation indices, only SDII and R25mm showed dominantly significant trends. Additionally, there were increasing trends in the frequency and duration at the southern and central regions of the city during the study period. Furthermore, El Nino-Southern Oscillation and Pacific Decadal Oscillation positively correlated with the duration and negatively correlated with the intensity and frequency of extreme precipitation. Thus, water management plans should be adjusted appropriately to reduce the severe impacts of precipitation extremes on communities and ecosystems.

Automated summary

The study reveals an upward trend in annual rainfall in Ho Chi Minh City, with significant trends in SDII and R25mm extreme precipitation indices, as well as increasing frequency and duration of precipitation in the southern and central regions. El Nino-Southern Oscillation and Pacific Decadal Oscillation are correlated with extreme precipitation patterns.