El Niño-Southern Oscillation-driven rainfall pattern variability in the Plain of Reeds

ABSTRACT The Plain of Reeds, a crucial agricultural region in the Vietnamese Mekong Delta, is experiencing rainfall pattern variability under the impacts of climate variability. It has shown substantial evidence of a demonstrable link between El-Niño Southern Oscillation (ENSO) and regional rainfall patterns in recent decades.This study investigates the influence of the ENSO on rainfall pattern variability within the Plain of Reeds by analyzing daily data series from 11 rainfall gauge stations, spanning from 1985 to 2020, based on non-parametric statistical methods and the rainfall anomaly index (RAI), examining rainfall pattern variation in relation to ENSO phases. The close links between ENSO events on rainfall pattern variability is verified. During dry periods, there is a decrease in annual rainfall, a delay in the onset of the rainy season (ORS), and an earlier end to the rainy season (DRS), resulting in fewer rainy days. In contrast, humid periods are marked by increased annual rainfall, an earlier ORS, and a later DRS, leading to more rainy days. Furthermore, rainfall intensity exhibited substantial inter-annual variability linked to ENSO. The findings reveal a complex interplay between ENSO and rainfall patterns in the Plain of Reeds. These results have critical implications for water resource management and agricultural planning in the region.