KUCHING: Heavy localised rainfall within the Ulu Katibas catchment area is believed to have caused the recent logjam at the confluence of the Katibas and Rajang rivers, says the Sarawak Forest Department.
Its director Datuk Hamden Mohammad said satellite data obtained last Sunday (March 3) showed about 10 sites where major slips or landslides occurred within the catchment area due to the heavy rain.
He said the slips were detected in the Lanjak-Entimau Wildlife Sanctuary, where no logging activity is carried out as it is a totally-protected area.
"Based on the hydrological data that we acquired from the Department of Irrigation, the higher intensity of localised rain that occurred within the catchment could have caused the landslides along Sungai Nyawai, Sungai Takai and Sungai Kalimau Besai, which are within the Ulu Katibas catchment.
"On average these slides are about the size of a football field but their occurrence was numerous within this area.
"The water level upriver was high, flooding the forest floor, bringing down all the debris and uprooting trees," Hamden said on Wednesday (March 6).
He was speaking to reporters after the opening ceremony of an international conference on sustainable management of tropical forests here.
The logjam occurred last Sunday (March 3), when residents of Song town were shocked to see large amounts of floating wood debris in front of the jetty.
A resident known as Luke Antas was reported saying that the wood was believed to have come from Ulu Katibas due to continuous heavy rain in the upstream areas.
Hamden said the department's personnel were still on site to monitor the situation and conduct a joint aerial investigation with the Sarawak Forestry Corporation and state Natural Resources and Environment Board.
He said the floating debris mainly consisted of small pieces of wood from uprooted trees, with no large logs unlike in previous logjam incidents.
"It's difficult to clean up the small wood pieces, so we leave it to nature. We will let it be washed out to sea," he said.
Hamden also said an initiative to clean up the Rajang River has been ongoing since last year.
He said about 8,000 tonnes of logs and debris had been removed from the river so far.
In addition, he said the department would install four log booms costing RM4mil in total in the Baleh River to prevent logjams.
