Summer is here! Time to get away and enjoy the sand and sea. This issue of Core Elements is devoted to sand, beaches, and deltas. Let’s look at three reports that offer new data around protecting beach sands and deltaic environments and populations.
Rasoul Sorkhabi
Editor, Core Elements
Sand Mafias
L Dunn/Shutterstock.com
An investigative article in Scientific American discusses how “organized crime is mining sand from rivers and coasts to free up demand worldwide, ruining ecosystems and communities.”
Defining sand: Sand is technically quartz-rich clastic mineral grain between 0.0625 and 2 mm in diameter.
Sand facts:
According to the United Nations Environment Program (UNEP), every year the world consumes 50 billion metric tons of sand.
The only natural resource more widely consumed than sand is water.
Rising demand: China holds the greatest demand for sand. Vince Beiser, author of The World in a Grain, notes that from 2011–2013, China used 6.6 gigatons of cement—30 percent more than what the USA used over the entire 20th century (4.5 gigatons).
Sand trafficking: The article reports on Abderrahmane, a researcher for the Institute for Security Studies in Africa, who used to investigate drug trafficking but has recently turned his attention to sand trafficking on the Atlantic coast of Morocco.
According to Abderrahmane, “more than half of Morocco’s sand is illegally mined.” He adds: “You cannot illegally mine sand in daylight if you don’t have people in high places.”
But it’s not just in Africa: Questionable sand mining occurs in many countries, including the USA.
In 2020, under grassroots pressure, the U.S. shut down sand mining operations by Cemex, which used to extract 270,000 metric tons of sand each year from beaches north of Monterey, California.
Can it be stopped?
Science can offer public education about how sands, beaches, and deltas are vital for human sustenance and ecological stability.
Grassroots awareness and activism, government regulations and legal actions, and international cooperation can help.
Technology exists to monitor illegal sand mining using satellite imagery.
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Fifty percent of the world’s population lives within 150 km of a coastline. This means that human activities, population pressures, and urbanization are increasingly damaging coastal ecosystems.
One example is coastal sand mining. A recent article in Science suggests restrictions are needed.
Types of sand:
Mineral sands are mined to extract heavy minerals such as zircon and ilmenite—all of which have industrial applications. Mineral mining consumes 10 percent of the global sand volume extracted.
Aggregate sands are used mainly for construction. Aggregate sands are preferable for concrete production, because their angular grains help concrete mixtures bind better. Smooth desert sand grains are best for glass making. Construction uses 85 percent of all sand mined globally.
Why it matters:
Excessive sand mining threatens coastal biotic communities, including aquatic plants, fish, mollusks, and crustaceans.
Sand mining has caused a 25 percent decline in revenue and a 30 percent decline in tourism in some areas, according to a 2019 report inCoastal Scenery.
Potential solutions:
UNEP has recommended a ten-point strategic plan to protect coastal sands. These include practices related to regulations and governance, research and mapping, and controlled sand mining.
Recommended practices:
Establishing buffer zones around fragile habitats can save them from sand mining.
Manufactured sand, derived from crushing hard rocks such as granite, can be substituted for beach sands.
More sand recycling: Only 20 percent of sand from construction waste is recycled; the rest ends up in landfills.
Two noted sedimentologists, Bilal Haq and John Milliman, recently published a study exploring the status of river deltas. This new study is a follow up to their previous work in 1996, in which a large number of scientists reviewed coastal subsidence around the globe.
What is a delta? River deltas are geomorphic features; however, economic geographers often consider them in a much broader sense. For example, the Pearl delta in China is 5,600 square km but the Pearl River Delta economic zone is 39,000 square km.
By the numbers:
Geomorphic river deltas cover 414,000 square km—only 0.065 percent of Earth’s land surface—but they are home to 4.5 percent of the world population.
Seven of the largest deltas are the Amazon, the Bengal, the Mississippi, the Mekong, the Niger, the Irrawaddy, and the Nile.
Deltas' importance:
Deltas have long been centers of civilization because of their fertile soil, abundant freshwater, diverse ecosystems, fishing, tourism, and access to the sea.
Deltaic basins host major oil and gas fields and operations.
Retreating beaches and coastal subsidence can be hazardous to human populations and economies as well as to coastal ecosystems.
Shifts at the deltas: The study highlights some changes at deltas over the past nearly three decades:
River diversion, upstream dams, and coastal urbanization have led to decreased sediment supply to deltas.
Slowly rising sea levels may one day flood deltas.
Beaches are in retreat because of wave-dominated marine erosion.
Salt-water intrusion into coastal aquifers—which are already over-extracted—and wetlands is causing decreased quality of freshwater aquifers and other salinity issues.
Massive extraction of groundwater and petroleum from deltaic basins will lead to subsidence. Reinjection of water may help mitigate this.
Go deeper: Read the full article in GSA Today and the previous expanded study here.
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