Tiếng Việt


Danang: Dredging and Dumping in the Ocean Impacts the Marine Ecosystem

Experts in environmental science and maritime ecology are all concerned about the plan to dredge and deepen the Tien Seaport channel by extracting 200,000 m³ of materials and dumping them somewhere off Danang.
The Danang People’s Committee has agreed in principle to allow the Vietnam Maritime Administration (Ministry of Transport) to research, survey procedures to implement the plan, but scientists are insisting that an environmental impact assessment (EIA) is vital before doing so.
The Danang marine ecosystem is in decline
Associate Professor Vo Van Minh, Council Chairman of the Danang University of Science & Education, believes that the material will have to be dumped off Danang if no other more suitable location is identified. However, an EIA is required to determine which other marine area, if any, would cause less environmental damage. 
“The waters around Danang are currently not protected from dumping,” said Mr. Vo Van Minh. “From an environmental point of view the dumping will certainly have an impact, especially on coral reefs and seagrass, which shelter the breeding grounds of a wide variety of marine animals. The environment will certainly be disrupted by the impact.”
Mr. Vo Van Minh stressed that an EIA would minimize damage to the lowest possible level. However, the marine ecosystem around Danang is already in serious decline due to deficient preservation and the impact of tourism and wastewater. “I hope that the EIA assessors will consult with the experts on their opinions,” added Mr. Vo Van Minh. “If not done well, this could seriously endanger the environment.”
According to Dr. Nguyen Tac An, former Director of the Institute of Oceanography in Nha Trang, a thorough EIA must take into account which dredging and dumping methods will be used. Inert materials just lying stationary on the seabed are not a problem, but, if they are disturbed, a great many issues may arise. Taking only dredging and dumping procedures into consideration is inadequate.
Dr. Nguyen Tac An explained that, in principle, dumping must be done far from residential areas, fishing grounds, protected waters and places of special marine value. Waters with strong currents must also be avoided.
“When sediment is deposited in one place, it gradually moves elsewhere,” Mr. An warned. “Dumping must be done with great care. The sand that is dredged up must be checked for harmful chemicals and poisons, which EIA assessors are well aware of. Digital maps of Vietnam are now available and must be examined before dumping in a certain spot. The EIA must take test samples, model the diffusion and particle size and consider the ideal schedule for the dredging and dumping.”
Mr. Nguyen Tac An also stressed that more channel dredging at the port is critical and doing nothing is not an option. The impact must be minimized however and the economy protected at the same time.
Ðà N?ng: Nh?n chìm v?t ch?t, lo ?nh hu?ng d?n sinh thái bi?n
Experts insist that the EIA must determine which dumping areas would cause the least environmental damage. Photo: LE PHI
Ðà N?ng: Nh?n chìm v?t ch?t, lo ?nh hu?ng d?n sinh thái bi?n
Dredging the Tien Sa port channel will produce 200,000 m³ of material for dumping near Danang. 
Concern for coral reefs
Speaking about dumping into the sea near Danang, Dr. Nguyen Thi Minh Phuong, DTU Dean of the Environmental & Chemical Engineering, believes that 200,000 m³ of dumped materials will certainly impact the marine ecosystem.
“We can be sure that the ecosystem will be affected,” explained Ms. Minh Phuong. “When we dump like that, we usually think that the materials will lie there forever, but that’s not the case because huge tides will carry it away. The seabed must be checked for coral reefs, which are of major concern. Coral can’t survive in muddy, murky water, they need light or the symbiotic algae of the corals and the entire reef will eventually die off.”
According to Ms. Minh Phuong, the seabed must deep enough, with no existing coral growth. However, the tides would drag the dredged materials around. Heavy sediments sink, but fine-grain sediments are transported everywhere.
“It is envisaged that affected area would be only 100 ha, but it in fact it would be much larger,” she explained. “The sediment at the site of the dredging is probably fine-grained, not coarse-grained. Over several years, it’ll be carried everywhere, depending on seasonal tide changes. Wherever the sediment travels, the coral reefs will die temporarily but may later recover.”
Ms. Minh Phuong remarked that, from an administrative point of view, any project will impact the environment but if the impact is judged less than the economic loss of the port, a tradeoff is inevitable. “But saying there’s no impact is untrue. Marine damage is very hard to control. While other ecosystems can recover given time, coral reefs definitely cannot.”
The 177 coral species around Son Tra peninsula
From 2016 to 2018, the Southern Institute of Ecology conducted a project entitled “Research on the preservation and recovery of biodiversity in dry and submerged ecosystems around the Son Tra nature preserve”. After being allowed to recover for almost three years, the coral coverage increased by 10%. The number of marine animals living in the reef increased and seagrass coverage went up by 20 to 30 percent.
In 2019, it was estimated that the waters around the Son Tra peninsula contained 177 coral species in 17 families and 52 genera. It was also discovered that there were 130 fish species in 32 families and 65 genera living in the coral reefs. The area also included three species of seagrass covering an area of 1 ha and 180 species of seaweed. However, the marine ecosystem there was already seriously damaged.
(Media Center)