Water released into Melamchi tunnel, Kathmandu Valley to receive water after the tunnel gets filled

Published On: November 28, 2022 08:02 PM NPT By: DHRUBA DANGAL

SINDHUPALCHOK, Nov 28: The Melamchi Water Supply Project has started releasing water to the tunnel from the headworks (source of origin) at Ambathan in Helambu from Monday.

The flow of water in the tunnel was halted during the rainy season fearing further damage to the headworks that were badly affected by floods during the previous monsoon.

Project Site Divisional Engineer Padam Bahadur Kunwar said that the sediments piled up at the mouth of the tunnel were removed after a long time and water was released to the 26.5-kilometer-long tunnel. 

“It took 10-12 days to repair the access roads damaged by the floods and to remove the sediments piled up at the headworks. “As soon as the works were completed, we started releasing the water," he told Republica.

According to Kunwar, the rainfall during this monsoon did not cause any damage to the headworks and the tunnel, except for normal accumulation of sediments. 

The headworks had sustained massive damage during the previous monsoon. Kunwar said that they shut the mouth of the tunnel at the headworks before the rainy season started in order to prevent possible damage to the structures.

Divisional Engineer Kunwar said that the water was released into the tunnel at the rate of 200-300 liters per second. According to him, it is estimated that it will take 12-15 days to fill the 26.5 km tunnel. 

Project spokesperson Rajendra Pant said that water distribution in the Kathmandu Valley will start after the tunnel gets filled. "Right now, water is being sent from temporary structures," he said.

On June 15 and August 1, 2021, the massive floods in the Melamchi River caused damage to the source of the project site. The floods had deposited 130,000 cubic meters of sediments along with large rocks and sand at the source of the river. 

The permanent headworks structure was under construction when the Melamchi floods occurred. Water was sent through a separate temporary structure.

Due to the lack of a permanent headworks structure, water from Melamchi River can only be distributed this year before the rainy season starts. 

The project has not yet started the headworks protection work. According to Engineer Kunwar, the project has been carrying out repairs and maintenance in the tunnel since last May to August. Such repair and maintenance work has to be done every year.

The project has entrusted the Asian Development Bank (ADB) with the responsibility of studying permanent headworks. ADB is the main donor of the project. As the current headworks at Ambathan is found to be vulnerable to floods and landslides every year, the debate on its restructuring is being raised at the policy-making level.

According to Pant, the spokesperson of the project, the ADB team conducted a study to find whether the headworks located at Ambathan can be brought into operation or it should be moved elsewhere. 

Although the team submitted a preliminary report to the project last June, a detailed report has not yet been submitted. 

"The deadline for receiving the final report from the ADB is December," he said.


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