The Mekong Delta is among the world’s largest. Not solely do thousands and thousands of individuals name it residence, it’s an agricultural powerhouse, producing roughly half of Vietnam’s complete rice harvest and practically three-quarters of its fruit, aquaculture, and fisheries merchandise.
However the delta — and the thousands and thousands who depend on it — is below risk, from growing saltwater ranges and drought.
The culprits are well-known: upstream dams, land subsidence and local weather change-induced sea-level rise.
However there may be one other important but much less acknowledged contributor: riverbed sand mining.
This apply not solely alters the river’s traits however exacerbates saltwater (or salinity) intrusion, particularly throughout drought years.
Salinity intrusion happens when seawater penetrates inland, primarily throughout the dry season (January to Could) when river circulate is lowered.
This phenomenon is worsened by a number of converging elements.
Land subsidence, brought on by extreme groundwater extraction, results in the sinking of land, successfully contributing to relative sea-level rise and growing vulnerability to saltwater intrusion.
In the meantime, local weather change-induced sea-level rise straight pushes salty water additional inland.
The delta’s sand mining business caters to the area’s development wants which has expanded in because of speedy urbanisation. Quite a few sand mining barges dot the Mekong mid-river and alongside its banks.
Riverbed sand mining considerably intensifies saltwater intrusion and drought in two methods.
First, sand mining deepens the riverbed, reducing the river’s base stage and enhancing tidal affect, which permits seawater to intrude additional inland.
Second, upstream dams entice sediment, and sand mining additional depletes sediment provide downstream.
This lack of sediment weakens the river’s pure obstacles in opposition to salt water, corresponding to stabilising mangroves and the increase of essential land. River deltas are shaped by continuous deposits of sediment over time.
Sediment is essential for sustaining these pure defences. With out it, the river loses its potential to counteract the drive of incoming tides and seawater.
The droughts of 2016 and 2020 have been among the many worst in latest historical past, with saltwater intrusion reaching unprecedented ranges. The 2020 drought was notably extreme, occurring earlier within the season and penetrating deeper inland.
These circumstances resulted in important agricultural injury, freshwater shortages and extreme impacts on the livelihoods of thousands and thousands.
The elevated exercise of riverbed sand mining throughout this era exacerbated the state of affairs.
Saltwater intrusion worsens drought circumstances. It damages crops by limiting the supply of freshwater for irrigation and consuming.
There are a number of sustainable practices which may mitigate the affect of sand mining and saltwater intrusion.
How satellites may help
Strict enforcement of sand mining rules, coupled with multi-scale monitoring methods, can cut back riverbed erosion and shield the river. One instance is sand mining actions being monitored utilizing satellite tv for pc photos throughout the delta in near-real time.
Measures to revive sediment circulate, corresponding to sediment bypass methods at dams, may help rebuild pure obstacles in opposition to salinity intrusion. Cooperative water administration agreements amongst Mekong River Basin nations can guarantee equitable water distribution and sustainable dam operations.
Selling salt-tolerant crops and built-in farming methods, corresponding to mangrove rice-shrimp farming, may help communities adapt to and proactively handle altering salinity ranges.
Though sand mining is commonly missed in discussions of drought drivers, its affect on saltwater intrusion and the river within the Mekong Delta is profound.
Addressing this concern via sustainable administration practices is essential for mitigating drought circumstances and guaranteeing the resilience of the area’s agricultural methods.
By understanding and managing the advanced interactions between human actions and pure processes, we will higher shield the Mekong Delta and its inhabitants from the escalating risk of drought.
Edward Park is an assistant professor at Nanyang Technological College in Singapore, the place he leads the Tropical Rivers Group investigating how rivers reply to pure disasters and human actions for sustainable basin administration.
Dung Duc Tran is a senior analysis fellow at Nanyang Technological College in Singapore and Vietnam Nationwide College Ho Chi Minh Metropolis, together with his background encompassing socio-hydrology and built-in water assets administration for sustainable deltas.
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