Sand Mining Hotspots in the Mekong Delta: Potential Signs of Unsustainable Replenishment

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Sand Mining Hotspots in the Mekong Delta: Potential Signs of Unsustainable Replenishment. Satellite tracking of sand mining boats from 2014 to 2020 found hotspots up 32.4%, most of them mined again on a 2-year cycle. That may be too soon for the riverbed to replenish before extraction resumes. Rachel Yu San Lau and co-authors, including Dung Duc Tran (HAPRI Senior Research Associate). Illustrative photo: on an eroded, collapsing riverbank in the Mekong Delta, a woman seen from behind photographs a sand-dredging barge loading wet sand in the middle of a wide brown river. Palms line the far bank under an overcast sky.

Sand Mining Hotspots in the Mekong Delta: Potential Signs of Unsustainable Replenishment

www.hapri.org

Dung Duc Tran — Senior Research Associate

A study co-authored by Dung Duc Tran (HAPRI Senior Research Associate) and colleagues tracked sand mining boats in the Vietnamese Mekong Delta and found that most mining hotspots recorded a recurrence interval of 2 years. The authors write that this potentially indicates a minimal timeframe of sediment replenishment before the same locations become economically viable for further sand extraction, and that the study sheds light on the potentially unsustainable scale of sand mining activities in the delta.

Context

Rampant and illegal river sand mining in the Vietnamese Mekong Delta has led to substantial sediment losses and bank erosion, the paper notes. Yet regulating it remains a significant challenge because of insufficient monitoring and enforcement efforts, which the authors partly attribute to limited data and technology.

To support an improved monitoring system in the delta, the study investigates the spatiotemporal changes in sand mining hotspots and their underlying drivers.

*Recurring hotspots, linked to riverbed incisions*

Methods

Using Sentinel-1A satellite data, the authors assessed the recurrence intervals of sand mining boats from 2014 to 2020 along the Hau and Tien branches of the delta's channel. They then examined how these hotspots were associated with riverbed incisions, drawing on bathymetry field surveys carried out between 2017 and 2020.

Key findings

Sand mining intensified from 2015 to 2020, particularly in the upstream section of the delta, where 70% of the activity was recorded.
The number of sand mining hotspots showed an apparent increase of 32.4%, and most hotspots recorded a recurrence interval of 2 years.
Of the 722 hotspots identified, 256 exhibited a 2-year recurrence interval.
A correlation was detected between sand mining hotspots and significant riverbed incisions, although the lack of spatial overlaps in some regions suggests other upstream influences like bank collapse and river damming.

Policy implications

The authors say the study aims to support informed decision-making and effective regulations that tackle excessive sand extraction, while offering valuable insights to similar deltas worldwide.

Keywords:

Vietnamese Mekong Delta
Sand Mining
Riverbed Incision
Sentinel-1 SAR
Sustainable Development

Link:

https://doi.org/10.1016/j.jenvman.2024.122435

Citation:

Lau, R. Y. S., Park, E., Koh, Y. Q., Tran, D. D., Kantoush, S. A., Binh, D. V., & Loc, H. H. (2024). Recurrence interval of riverbed sand mining hotspots in the Mekong delta: Potential indications of unsustainable replenishment rates. Journal of Environmental Management, 370, 122435.