The Ombilin River Suddenly Clears After Floods, Experts Give Explanations

The Ombilin River is clear after the flood. (Sumbarpost/IG)

JAKARTA - The natural phenomenon has again stolen public attention after a recording circulated showing the clarity of the flow of the Ombilin River in West Sumatra. In various videos that were widely shared by netizens, the river water seemed to be clear green like beautiful rivers abroad, resulting in admiration.

One of the uploads posted by the Instagram account @core_id shows the flow of the Ombilin River receiving water supply from Lake Singkarak looks very clear when passing through residents' villages.

The clear river water with a green rona made many people compare it to the Aare River in Switzerland.

In the description of the upload, it was stated that the clarity of the water emerged after heavy rains in the last few days.

"Residents share the condition of the Ombilin River whose water comes from the overflow of Lake Singkarak, after heavy rains that hit West Sumatra, blue, green and clean. This is the natural condition if it is not damaged," the account wrote in the caption section.

The video immediately invites various reactions. Many social media users had doubts about the authenticity of the river color because it was considered too perfect for the area. Various comments also filled the upload column, ranging from skeptics to those who were amazed.

However, this doubt was denied by someone who claimed to be a local resident. He ensured that the water condition seen in the video was real.

"This is real. My house is 3km from this river, the water is clear from the singkarak lake. If it is shallower than this, it is clear that the river base is rocks and sand, very clear," commented one netizen.

Regarding the change in water color which is now very clear, geologists provide a scientific explanation. Head of the BRIN Center for Geological Resources Research, Iwan Setiawan, said that clarity was a natural process after a series of heavy rains.

"I think it's a normal natural phenomenon when heavy rains last for a long time have brought loose soil material and other materials were swept away into the river during the flood," he said when contacted by VOI on Wednesday, December 3, 2025.

According to him, this natural cleaning process occurs when river flows that have brought mud, sand, and various organic materials are starting to weaken and stabilize again. At that stage, sediments that initially irrigated the water would settle on the ground, while calmer currents helped restore the clarity of the flow.

This is why, after the flood phase passes, the river conditions can appear much cleaner to reach a level of clarity that shocked the public, as seen in recent phenomena.

"After finishing, the river cleans itself again until the water is clear." he said.

Although now looking charming, this river previously experienced an alarming condition due to flash floods that hit three provinces in Sumatra on November 26. Large currents carried wood, mud, and various other materials into the lake, making it the end point of flooding shipments from a number of large rivers upstream.

Data released by the National Disaster Management Agency (BNPB) through the Flood and Landslide Emergency Management Dashboard for the areas of Aceh, North Sumatra, and West Sumatra in 2025 showed the impact of the disaster was very large. As of Wednesday afternoon, December 3, 2025, 753 people died, 650 people were missing, and 2,600 people were injured.