River Sand and Gravel Mining/Dredging is Impacting Rivers, Groundwater, Water Quality, Sediment Availability, and Coastal Saltwater Intrusion

      A new meta-study analyzing over 400 previous studies was recently published in Review of Geophysics about the dredging and mining of river sand and gravel and its impacts. The study confirmed that river sand and gravel are often extracted much faster than they can naturally be replaced. This results in significant impacts. 

     According to ZME Science:

“The riverbeds sink, banks collapse, groundwater drops, saltwater moves inland, habitats disappear, and communities lose land and livelihoods.”

     They note that river sand and gravel are preferred for concrete production and make up to 70% of concrete by volume. Global extraction of sand and gravel amounts to about 50 billion metric tons per year.

“Mining lowers the riverbed and changes how water moves. Faster, more turbulent flows can scour the channel and push erosion. Scientists sometimes call this hungry water: flow with enough energy to carry sediment, but too little sediment available, so it begins eroding the river itself.”

“Over time, the channel can deepen, widen or straighten. Banks can collapse, which can threaten houses, roads, and farmland well beyond the mining site. The effects can also travel underground. Rivers interact with nearby groundwater, so a deeper channel can contribute to falling water tables. In coastal deltas, it can also allow seawater to move farther inland, threatening freshwater supplies and agriculture.”

“Sandbars, gravel beds and shallow channels provide habitat and feeding or breeding grounds for fish and aquatic insects. Dredging can remove those features directly while stirring fine sediment into the water, reducing light and degrading water quality.”

     They note that sediment replenishment rates for rivers need to be better understood. They suggest that areas where dredging would have less impact should be identified and prioritized for extraction. The good news is that after mining is stopped, rivers can build up sediment and get back to normal sedimentation over time.

     The paper’s abstract summarizes the impacts and notes that problems are likely to develop where extraction is growing fast, such as Africa and Asia:

“In most documented cases, annual removal exceeds bed-material supply several-fold, producing channel incision, bank collapse, declining groundwater tables, deteriorating water quality, and inland migration of saline water in coastal areas. These physical changes cascade into habitat loss, infrastructure damage, and livelihood insecurity, especially across rapidly developing regions of Asia and Africa.”

     Below are figures from the paper. The first explores global demand and consumption of river sand and gravel resources.

     The figure below shows geomorphic impacts of river sand and gravel extraction.

     The figure below shows a conceptual framework of river-aquifer interactions after sand and gravel extraction.

     Impacts of river sand and gravel mining on water quality are depicted below.

     Impacts of river sand and gravel mining on coastal erosion, sediment starvation, delta formation, tidal processes, and saltwater intrusion on aquifers are shown below.

     The following section is from the paper’s conclusions:

“The synthesis of hydrogeomorphic evidence indicates that physical processes form the main pathway through which mining effects propagate across space and time. Removal of bed material alters channel gradients and flow structure, initiating incision, knickpoint migration, bank instability, and changes in sediment transport and connectivity. These responses differ between gravel- and sand-dominated rivers and between artisanal and mechanized extraction, but they share a common pattern: once sediment removal exceeds replenishment, impacts are rarely confined to the excavation site. Over years to decades, local disturbances accumulate, lowering water levels, modifying flood dynamics, and reducing sediment supply to downstream rivers, deltas, and coasts. Ecological and socio-economic impacts reported across regions—such as habitat loss, declining fisheries, infrastructure damage, and livelihood insecurity—are therefore closely tied to these hydrogeomorphic adjustments, even although they are seldom quantified alongside physical process metrics.”

 

 References:

   

The environmental problem you’ve never heard about: Sand mining is quietly reshaping rivers around the world. Mihai Andrei. ZME Science. August 13, 2026. The environmental problem you’ve never heard about: Sand mining is quietly reshaping rivers around the world

River Sand and Gravel Mining: Global Drivers, Impacts, and Pathways for Sustainable Management. Edward Park, Christopher R. Hackney, Dung Duc Tran, Mette Bendixen, Jim Best, Kai Wan Yuen, Hannah Runeckles, Md Sadiul Alam Chyon, Karl Kästner, Sonu Kumar, Halinishi Yusuf, Vanessa Lamb, Lars L. Iversen, Aelis Spiller, Rajiv Sinha, Eduardo Francisco da Silva, Enner Alcantara, Chengcheng Wu, Chengpeng Lu, Chu Jian, Jingyu Wang, Nguyen Duc Thien, Lian Feng, Priyank Pravin Patel, Jiachun Huang, and Adam D. Switzer. Review of Geophysics. Volume 64, Issue 3. July 20, 2026. River Sand and Gravel Mining: Global Drivers, Impacts, and Pathways for Sustainable Management - Park - 2026 - Reviews of Geophysics - Wiley Online Library