- English
The Vietnamese Mekong Delta (VMD),
a cornerstone of national food security, is increasingly
affected by salinity intrusion arising from the
combined influences of upstream hydropower development,
climate change, and sea-level rise. Despite
growing attention to this issue, the long-term hydrological
mechanisms shaping these changes remain
insufficiently understood. This study examines freshwater–
salinity dynamics along the Co Chien River
over the period 2000–2024, applying nonparametric
Mann–Kendall (MK) tests and Sen’s slope estimators
to identify spatio-temporal trends, alongside a
comparative assessment of hydrological variability
between coastal and inland zones. Spearman correlation
analysis is used to distinguish the relative
contributions of climatic variability and upstream
hydrological regulation. The findings indicate a
pronounced landward shift of the salinity boundary,
with inland monitoring stations exhibiting relative
increases in minimum salinity (Smin) exceeding
3% per year. Of particular significance is the role
of declining dry-season upstream discharge, which
emerges as the principal driver of salinity intrusion,
exerting a stronger influence than ENSO-related climatic
variability. A notable spatial paradox is identified:
while coastal areas experience consistently high
yet comparatively stable salinity conditions, inland
transition zones are characterised by pronounced hydrological instability. These patterns point to the
limitations of predominantly localised engineering
responses and underline the need for more anticipatory,
inter-regional approaches to water governance.
Integrating upstream discharge thresholds into earlywarning
systems offers a pathway towards enhancing
the resilience of livelihoods in the delta’s most vulnerable
transitional landscapes.
- English
