Vulnerable riverbeds, shorelines and even fresh water lakes are being damaged by sand dredgers across the world. Sand – a necessary part of making concrete used extensively in the construction industry – helps build the cities of tomorrow. But as these cities go up, the natural environment around them suffers.
This is what will be happening soon in Bangladesh, now that the government has decided to undertake long-term dredging operations in the Jamuna River. The purpose is to clear river channels for shipping lanes. The government will also be making a hefty profit by selling the dredged sand to Maldives and Singapore.
While it claims that it will stop dredging operations should it become clear that environmental damage is, in fact, being done, our river eco-systems cannot avoid this kind of devastating damage because by definition to dredge is to damage.
Studies of the environmental impact caused by lake and river dredging in other parts of Asia unquestionably prove this point.
China’s growth is based on its ability to get large quantities of construction sand, and this building sand must come from somewhere. In the past, it has mainly been dredged up from the Yangtze River. But so damaging was the dredging that it has been banned. Now Chinese dredgers are scooping up sand from Poyang Lake. This lake feeds into the northern end of the Yangtze River.
Recent satellite images prove that it is having a widespread and detrimental impact. The photos show that the dredging has widened the river channel significantly. The old sandbars are nearly unrecognisable today. Natural habitats along the shorelines have been deeply disturbed and aquatic life has disappeared due to the severity of the dredging practices. The balance of nature has been drastically changed.
Dr James Burnham, an ecologist with the University of Wisconsin and the International Crane Foundation claims, “Sand mining has compromised the ecological integrity of the lake by contributing to less predictable seasonal water fluctuations and to a series of recent low water events.” He also says that sand dredging at Poyang Lake is putting the survival of Siberian Cranes and Oriental White Storks at risk. Serious damage is being done to both fresh water reserves and lake habitats.
A similar assault is also taking place in India’s rivers. Though the government there is making efforts to regulate sand dredging and police widespread illegal dredging, river dredging is so rampant that the state has almost lost the battle to protect its rivers. Their degradation is apparent all across the nation. And it will only get worse before it gets better because India’s sandy rivers feed the vast appetite of its booming construction industry.
India will succeed in building a million more homes to house its poor, but those people will also live in degraded natural environments because river dredging takes a very heavy toll on the life of rivers. It harms biodiversity, affects water turbidity and water table levels. It can also hurt fisheries and damage farmlands. It promotes riverbank erosion and creates unexpected land losses; flooding can become much more severe as a result. These are some of the consequences of river dredging. The question is not whether there is harm caused by dredging, but how much harm? In the case of India, not to mention China, it’s obviously severe.
Now, even Bangladesh is joining in the sand-dredging craze. And the Jamuna dredging project and ensuing exports to Maldives and Singapore raise weighty environmental questions about a) the destruction of Jamuna aquatic ecosystems and b) the heavy metal content and contamination of the sand being dredged.
While the government vows that it will stop dredging if it learns there is environmental damage being done to the river, how likely is this, given that it takes years to fully understand the destruction that is taking place right from the start? Given the hard proof that plant, fish and wildlife devastation happens wherever dredging happens, how could there not be grave eco-system injury?
Professor Quamrul Haidar of Fordham University, New York, who has studied the adverse impact of river dredging in Bangladesh claims there are two main adverse impacts caused by the dredging. One is precipitated by the dredging process itself; the second is triggered by the disposal of the dredged materials.
He argues that as dredging takes place “effects may arise due to the excavation of sediments at the bed, loss of material during transport to the surface, overflow from the dredger while loading, and loss of material from the dredger and/or pipelines during transport.”
What’s more, dredging disrupts the “composition, diversity and resilience” of the river in a multitude of ways. For example, river banks become more susceptible to erosion. This, in turn, can, cause even greater silt build-up in the river, making navigation of the river’s channels by ships more, not less, difficult.
As with China and India, erosion also disturbs and kills riverbank vegetation, stripping the banks of natural plant cover, which is necessary for shade. This then creates deeper light penetration, which, over time, increases water temperature, giving rise to fish migration.
Professor Haidar says that the “loss of natural habitat can render newly dredged habitats unsuitable for shallow-water fish” seeking refuge from river currents. And non-native species can become more invasive because of these deeper habitats. This makes them “more vulnerable to exploitation.”
There’s no question: Bangladesh’s river dredging business will damage the Jamuna River. The only debate will be: who will pay for its repair?
Significant is also the potential health and safety implications that may be created by selling contaminated sand.
According to Bangladesh Poribesh Andolon (BAPA), the Jamuna-Brahmaputra rivers are among the 32 most polluted in Bangladesh. They contain vast quantities of chemical mixed effluents. BAPA claims these rivers “are victims of dangerously toxic industrial discharges, including mercury, lead, chromium, cadmium, arsenic, potassium, calcium, manganese”, and many others.
The Brahmaputra-Jamuna riverbed sediments, in particular, are known to have extremely high levels of chemical mixed effluents and lubricants. They also contain extremely elevated amounts of ammonia, sulfur dioxide, calcium chloride, and sodium hydroxide mixed into river floor sediments. Sodium hydroxide is used by industries for the manufacturing of pulp, paper, textiles, detergents, and drain cleaner. The two rivers also hold huge, caustic volumes of sulfuric acid, which is exceedingly corrosive to metals, biological tissues – even stones.
Full details are available from the link below:
Source URL: Google News