Dredging at Terengganu estuary will harm ecosystem, experts warn
PETALING JAYA: Dredging as a method to deepen shallow waterways could do more harm than good, say environmental experts.
The so-called “environmental dredging” is a double-edged sword as it could affect both the ecosystem and the livelihood of those depending on fishing in the long term, the experts said, when commenting on dredging at an estuary in Terengganu.
Following claims by environmental group Ecoswed Initiative that sand mining had damaged the coastal forest and marine life at an estuary in Kuala Baru Setiu, the mining project developer responded by saying the dredging benefitted some 1,000 fishermen from the surrounding villages whose income had been affected by the shallow estuary.
M&Z Production Industry Sdn Bhd gave an assurance that it did not damage the environment as the company’s operations were based on “method statements and hydraulic research”.
A fishermen’s association in Setiu also supported the project as it “guaranteed a source of income”. The association said the shallow estuary had made it difficult for fishermen to catch fish or carry out related activities.
However, environmental experts said while the fishermen’s concern was valid, dredging was not a long-term solution to the problem.
Jarina Mohd Jani, a human ecology expert, explained that the estuary became shallow due to sedimentation as the Setiu River’s flow had been compromised.
Jarina said the river currents were not strong enough to flush out sediments and had even received more due to the strong wave impact of the South China Sea.
She said dredging would only exacerbate the problem.
Edlic Sathiamurthy, a hydrology expert at Universiti Malaysia Terengganu (UMT), said dredging would physically alter the ecosystem, causing long -term damage that could be permanent to the estuary, the coastline and other interconnected ecosystems.
Because of this, he said, fundamental hydro-dynamic processes such as the flow of the river and “tidal intrusion-recession balance” would be further disrupted.
Disruption of this natural balance would modify the sediment transport patterns to the nearby coastline, causing more sedimentation inside the lagoon and estuary and, at the same time, depriving the coastline of sediment supply.
As a result, the lagoon and estuary would become shallow again while the coastline would erode.
“This is damaging to the coastline as it needs the sediments to act as a physical barrier against the direct onslaught of the South China Sea,” he said. “If this prolongs, the coastline will erode and even be destroyed, causing massive damage to the wetland ecosystem presently protected by the sandy coastline.”
Sathiamurthy said that once an area had been dredged, the practice must continue to maintain the depth of water bodies.
“This hinders the river system from regaining its natural capacity so that it has the optimal might to regulate itself and bring balance to the ecosystem. Once the river can no longer regain its natural capacity, dredging will become a routine necessity. At that point, you have no choice but to continue the costly practice.”
Meanwhile, Jarina believes that the project will leave a permanent and irreversible impact, despite assurances by the developer that they would replant the felled trees in the estuary once the project was completed.
“I am worried about the success rate for the replanting efforts once the project is over because it seems that much of the topsoil – the most nutrient-rich part – has been excavated.
“Note that the coastal forest is already a nutrient-poor ecosystem. After the topsoil is gone, what sort of soil is left? Whatever replanting action is taken, it will have to be done as soon as possible with extra care simply because of the damage already caused as we speak,” she said. - FMT
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