LAND CLEARING, SAND MINING AFFECT RIVERS

New Straits Times, 16 April 2007

JOHOR BARU: Rampant land clearing and sand mining have made Kota Tinggi prone to flash floods.

With over 100 tributaries converging into Sungai Johor, which cuts through this historical town, it is prone to flooding whenever there is excessive rain. It bursts the river’s banks and inundates the town. The major tributaries include Sungai Semanggar, Sungai Sayong, Sungai Sebol, Sungai Linggiu, Sungai Tengkil and Sungai Lebak.

Dr Noor Baharim Hashim, a senior lecturer at the Department of Hydraulics and Hydrology in the Faculty of Civil Engineering, Universiti Teknologi Malaysia, said the research team’s concerns were not only about flash floods but also about the aftermath of a flood.

"An increase in the inflow of freshwater into the estuarine areas will affect the aquatic life for up to three weeks," said Noor Baharim. "Many of the fish die or swim to other rivers resulting in dwindling catch for the local fishermen.

"Clams also become infected by bacteria due to high freshwater content."

He said the nutrient level of the water samples collected from the Straits of Johor showed there was a risk of algal bloom in the region.

"There is increasing concern about the oversupply of nutrients from multiple sources at the Sungai Johor estuary. This has ecological effects on the shallow coastal and estuarine areas."

The effects include a loss of aquatic habitat and seagrass, an essential food for dugong and herbivorous fish.

Noor Baharim said the authorities could adopt best management practices (BMP), which included building buffer zones and ponds to eradicate flash flood woes.

A research programme to monitor the water quality and velocity is also vital, as an efficient flood warning system can predict a flood two days in advance. Noor Baharim said land-clearing activities should not be carried out , especially during the monsoon period.