Practical, Local Paths to Slow Elevation Loss in the Vietnamese Mekong Delta

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Practical, local paths to slow the sinking of the Mekong Delta. A study co-authored by Edward Park, Dung Duc Tran and colleagues argues that tighter sand-mining licences, tiered groundwater tariffs and rain- and surface-water alternatives can slow subsidence without waiting for transboundary talks. Edward Park, Dung Duc Tran (HAPRI Senior Research Associate) et al. A Vietnamese woman, seen from behind, fills large glazed rainwater jars from a roof gutter beside a delta canal. An unused groundwater pump sits on a cracked, sunken concrete step. Rice fields, wetland trees and a small boat lie across the water under an overcast sky.

Practical, Local Paths to Slow Elevation Loss in the Vietnamese Mekong Delta

www.hapri.org

Dung Duc Tran — Senior Research Associate

A paper co-authored by Dung Duc Tran (HAPRI Senior Research Associate) with Edward Park, Philip S.J. Minderhoud, Ryan Clarke and Faith Ka Shun Chan argues for a policy strategy that first targets two local pressures on the Vietnamese Mekong Delta, sand mining and groundwater extraction, buying time for longer-term basin and climate agreements. The delta feeds 18 million people and is sinking because four pressures act in concert.

Context

The Vietnamese Mekong Delta is considered one of the world's most vulnerable delta regions, yet the authors note that the local pressures behind its elevation loss, and actionable solutions to address it, remain insufficiently studied. Four pressures act together on the delta: upstream dams, rising sea level, river-bed sand mining and groundwater withdrawals.

The large-scale causes of subsidence are well recognized. What the authors find underexplored and under-implemented are actionable, local-level management solutions that could slow subsidence and salinity intrusion immediately, independent of slow international negotiations over dams and climate.

Methods

The paper brings together evidence on the four pressures driving the delta's elevation loss, draws on scenario modelling of reduced groundwater pumping and provincial sand-quota cuts, and considers the policy options open to Vietnam at the local level, before setting out a strategy of locally actionable measures.

Key findings

Among the four pressures acting in concert on the delta, upstream dams have already cut sediment delivery by 70%–83% (a projected 96% if all planned projects proceed), and mean sea level is rising 1.5–2 cm/yr.
River-bed sand mining now removes about 3 Mm³ a year and deepens channels by up to 15 cm/yr, while groundwater withdrawals of approximately 2.5 Mm³ a day have accelerated land-surface subsidence from under 3 cm/yr in 2006–2010 to peaks of 5–6 cm/yr today.
Scenario modelling shows that halving pumping would stabilize aquifer heads and cut subsidence by about 50% within a decade, while provincial sand-quota cuts of 30%–50% would slow bed incision and ease salinity intrusion, reducing the irrigation deficits that drive further pumping.
Because dam and climate remedies depend on slow transboundary negotiations, the authors argue for a concentric policy strategy that first tightens sand-mining licenses, enforces tiered groundwater tariffs, and scales up rain- and surface-water alternatives.

Policy implications

The authors state that practically stricter policies are needed to ensure the Vietnamese Mekong Delta's sustainability and resilience.

Keywords:

Vietnamese Mekong Delta
Land Subsidence
Sand Mining
Groundwater Extraction
Salinity Intrusion
Water Management

Link:

https://doi.org/10.1016/j.geosus.2025.100335

Citation:

Park, E., Tran, D. D., Minderhoud, P. S., Clarke, R., & Chan, F. K. S. (2025). Practical paths to halt elevation loss in Vietnamese Mekong Delta. Geography and sustainability, 6(5), 100335.