Arunachal, Assam on high alert as Siang water rolls on

Assam is passing through deep anxiety with eyes fied on the danger level as the Tsangpo fed river of Siang rolls on to Brahmaputra near Passighat.

Till midnight, the water level of the Brahmaputra was below danger level at Dibrugarh but the next reading shall be taken in the morning today.

Generally it takes 24 hours to reach Dibrugarh from Siang and all eyes were on the 2000 level, which was the highest recorded at Siang.

All these had happened as China's Tsangpo river swells after heavy rainfall.

This was the highest discharge of water in the past 50 years in Tsangpo, called Siang once it enters India, and joins with two other rivers downstream to form the Brahmaputra. it contributes 30% of the river Brahmaputra. At Passighat.

The administration in East Siang district of Arunachal Pradesh has advised people living along the banks of the Siang to "remain alert but not to panic" as heavy rain in China had led to a massive discharge of water into the river Tsangpo.

The Tsangpo, which originates in China, is called the Siang after it enters India through Upper Siang district in the northeastern state. This means that if the Tsangpo swells because of a huge inflow of water, the possibility of a rise in the levels of the Siang cannot be ruled out. The Siang joins two other rivers — the Lohit and the Dibang — downstream to form the Brahmaputra.

In a circular issued on Wednesday, Tamiyo Tatak, deputy commissioner of East Siang, alerted the people, but asked them to stay calm even as he cautioned them against venturing into the river for swimming, fishing or other activities.

The circular said that according to reports sent to New Delhi by Beijing "due to heavy rainfall in Chinese portion, the Tsangpo river is swelling with observed discharge of 9020 cumec" at 8 am on Wednesday.

A discharge of 9,020 cumec would be equal to 9.02 million litres of water flowing in the Tsangpo per second. This is stated to be the highest discharge in the river in 50 years.

"We have issued the circular as an advisory so that people are careful. But there is no reason to panic at the moment….," Tatak said to media

Anxiety in Assam

Since any swelling in the Tsangpo and the Siang could lead to a possible rise in water levels in the Brahmaputra, Assam is also on its toes.

"There is a gradual rise in the water levels of the Brahmaputra, but it is not flowing over the danger mark in Dibrugarh. There is no cause to panic yet," said Dibrugarh deputy commissioner Laya Madduri.

Turbidity and turbulence in Siang

Last week, East Siang district officials had issued an advisory asking people to refrain from entering the Siang as "unusual waves" had been causing a fluctuation in the flow of the river over the past fortnight. "Such big waves have never been seen in the Siang. The volume of water flow is the same, but the river has become turbulent. Maybe it's the result of heavy landslides in China affecting the flow of the river or an impact of some major construction activity," East Siang deputy commissioner Tatak said.

Landslides the possible reason

However, a study released in December by two Indian researchers, Chintan Seth and Anirban Datta Roy, had suggested that landslides caused by a series of earthquakes in Tibet could have been the reason for the darkening of the Siang.

The study said debris from the landslides had caused partial blockages at three locations on the Tsangpo, leading to formation of natural dams extending nearly 6 km over a 12 km stretch.