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Authorities still have no answer to cause of logjam

on 02 November 2010.

IT HAS been nearly a month since the logjam disaster along the Rajang River, Malaysia’s longest river, but the authorities have yet to determine its causes and the extent of the environmental damage caused.

Certain quarters, including river dwellers, are convinced that uncontrolled logging is to blame, judging from the type of debris ranging from waste logs and cut wood to commercial logs.

On the other hand, others say timber companies should be absolved of all blame.

Whatever the causes are, the disaster is an indication that unsustainable activities have to be addressed transparently, urgently and effectively by all stakeholders.

A local expert told StarMetro that a disaster of such magnitude could be attributed mainly to large-scale land clearing activities.

“Those who have cut down the numerous logs and then disposed of them throughout the upper Baleh catchment area are the most likely culprits.

“Some may blame the weather but I am sure there have been similar weather conditions in the past where there were no reports of logjams,” environmental chemist Prof Lau Seng said.

According to him, large-scale land clearing would change the hydrological characteristics of the catchment area.

“It increases the runoff, causing erosion and resulting in stream overflows and soil deposits in rivers, making them shallower. This will eventually lead to flooding.

“The faster runoff also means the water has higher kinetic energy and will be able to carry more weight, thus washing down debris like waste logs and branches in its path,” he added.

Lau, who is the director of the Centre for Technology Transfer and Consultancy at Universiti Malaysia Sarawak, said that the clearing of land and debris piling could also obstruct the flow of water and force water to seep into the ground.

When the extent of soil water saturation is high and spread over a large area, then the saturated soil would move under gravitational force. This large-scale movement of soil is known as a landslide or, if the soil is in a slurry form, a mudslide.

Lau said the landslide or mudslide that caused the logjam could not have happened overnight but could have been the result of accumulated water seepage over a period as water moved very slowly in the ground.

In short, he said the logjam was the “result of excessive land clearing activities that were not done in the best interests of all.”

“This is not natural disaster,” he insisted.

If there was any lesson to be learned from the logjam, Lau said the people should insist that all resource harvesters must comply with standard environmentally wise practices. He added that they should also ask for better enforcement measures.

“We can develop an area but we have to do it in a sustainable way,” he said.

“The logjam is only a symptom of how bad the environmental situation is. The cause includes excessive activities on land,” he added.

On the extent of the environmental damage, Lau said one of the most obvious was the amount of different fish species killed .

“Other damage is more difficult to quantify, such as damage to the spawning grounds and to the food webs,” he said, adding that the damage also depended on the amount of suspended solids (SS) in the river.

He said the SS could be high and deposition of these SS onto the riverbed might bury benthic organisms (comprising crabs, prawns and snails) and kill them.

“These organisms are food for the fish and when the food becomes scarce, fewer fish can be supported,” he said.

The most obvious impact is the drastic decrease of fish in the river and locals, particularly those staying between Kapit and Sibu, who rely on riverine fish would be affected by this situation in the coming months.

“If the benthic organisms are greatly affected, then the quantity of fish in the river will take a longer time to recover,” he warned.

“For those in the upper Baleh or near the estuary like from Sarikei and Igan, the impact will be much reduced as tidal dilution would buffer the muddy water,” he said.

Lau was of the opinion that the authorities should take stock of the existing situation in the Rajang basin as well as in other river basins.

“We need to know quantitatively which areas are severely damaged, moderately damaged or slightly damaged,” he said.

He proposed that as a short-term measure, catchment clean-ups be carried out.

Waste logs and other debris should not be dumped indiscriminately and secure places should be provided as disposal grounds which are far from rivers and runoff paths.

Long-term plans include protecting headwater areas, steep slope areas and buffer strips along all waterways, he said.

He said the government must make sure degraded areas were rehabilitated by planting indigenous trees and monitoring their growth as not all seedlings could survive in degraded areas.

“The state should zone out environmentally sensitive land for conservation purposes,” he said.

Another way forward is to set up an integrated management for the entire Rajang River basin and take into consideration the needs of all stakeholders like foresters, plantations, longhouses/villages/townships, river transport, subsistence farming, the ecological needs of fish and other organisms, public water supply, recreational water demand and industrial demand for water.

Lau said local people should be empowered to be the custodians of the river, incorporating traditional knowledge as well as modern technology in the management of the river basin.

“The people need to understand the concept, the authorities needs to learn to share their responsibilities and the authorities, industries and land users need to give greater consideration to environmental or ecological needs,” he said.

Extracted from The Star.

Arkib Berita

Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia Telephone: +60 82581000/+60 82581388, Fax: +60 82 665 088, Email: corporate@unimas.my
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