Headwater phenomenon is common during monsoon, public must exercise caution, experts say

SHAH ALAM - Many are unaware of the danger of the headwater phenomenon during monsoon season as it could pose a fatal risk.

Experts advise people to exercise caution when planning vacations near hills and rivers.

Describing it as a common natural disaster, Universiti Teknologi Malaysia geologist Dr Azmi Hassan said the headwater phenomenon occurs when a gush of water from a hillside suddenly runs through a river.

This causes a quick increase in water volume and velocity in a river’s upper reaches, he added.

When asked on the sign what to expect from the phenomenon, Azmi stated that there will be dried leaves and wood flowing in the river.

"Another sign is when the water turns murky, or blackish. "These are the warning signs that people should be aware of," he told Sinar Daily.

Earlier today, a horrific video showed Malaysians encountering the headwater phenomenon at Rimba Cafe Kuala Kedua, Baling, Kedah.

TikTok user @calelelelele's one-minute-and-39-second video went viral on Twitter.It garnered 442,000 views, 4,995 retweets, and 6,350 likes.

A Twitter user, @liyanaliyana, who uploaded this video, said Malaysians should stop any recreational activities located near rivers or waterfalls, especially during this monsoon season.

Dr. Mariney Mohd Yusoff, a geologist at Universiti Malaya, agreed that the headwater phenomenon could be dangerous, and that most rivers in Malaysia, including those in Sabah and Sarawak, were at high risk.

She explained that the headwater phenomenon occurs due to heavy rainfall in the river's upstream regions.

"Malaysia is located near the equator; so it is normal to continuously receive heavy rainfalls," she added.

She explained that it was normal for the upstream regions of the river to encounter heavy rains.

"Upstream regions of the river have their own function where they act as water catchment.

"Usually the watershed happens in a waterfall because it has a high gradient from the rocks," she added.

Bad weather and the presence of clouds were also indicators of the headwater phenomenon, Mariney said.

"If it is cloudy in the upstream regions of the river, it is a sign of a headwater phenomenon," she said.

Recreational and ecotourism spots located in the vicinity of rivers and waterfalls in Malaysia should be more aware of the safety of the people because there possibilities for the headwater phenomenon especially during this monsoon season.