1Department of Oceanology, Meteorology and Hydrology, Faculty of Physics and Engineering Physics, University of Science, Ho Chi Minh City70000, Vietnam.
2Vietnam National University-Ho Chi Minh City, 70000, 227 Nguyen Van Cu Str., Cho Quan Ward, Ho Chi Minh City, Vietnam.
*Corresponding Author: Truong An DANG, Department of Oceanology, Meteorology and Hydrology, Faculty of Physics and Engineering Physics, University of Science, Ho Chi Minh City70000, Vietnam. Email: dtan@hcmus.edu.vn
The long xuyen quadrangle (LXQ) serves as a critical cornerstone of rice production within the Vietnamese Mekong Delta, yet a paradox currently exists where traditional monotonic statistical tests classify the region’s rainfall as “stable,” contradicting farmers’ reports of intensifying water scarcity due to climate change.
This study resolves this discrepancy by investigating the spatiotemporal evolution of rainfall (1984-2022) using the advanced innovative trend analysis (ITA) method, contrasted with the standard Mann-Kendall (MK) test and analyzing teleconnections to identify asymmetric ENSO modulation on local hydrology.
While MK tests showed no significant trends for inland stations (p>0.05), ITA successfully unmasked a critical “hidden” drying trend in the lower rainfall quantiles, implying that “dry years are becoming drier” Spatially, coastal stations (Ha Tien, Rach Gia) exhibit accelerated drying trends driven by weakening Southwest Monsoon circulation. Teleconnection analysis reveals a robust, asymmetric ENSO modulation: El-Nino phases reduce dry-season rainfall by up to 41.2%, whereas La-Nina phases fail to provide an equivalent compensatory surplus (increasing only by 20.1%).
Climate adaptation, ENSO asymmetry, Innovative trend analysis, Long xuyen quadrangle, Meteorological drought
