Mochu swells but no major flood reported as of midnight

Flood: Residents of Punakha and Wangdue valley, who were evacuated to safety were asked to remain at higher grounds as of late night yesterday with impeding dangers from a possible flood after the Lemthang Tsho in Laya burst around 6.30pm yesterday.

Around 11pm, Lyonchoen Tshering Tobgay cautioned the residents to not return home before dawn, or unless the disaster management department declares it safe given the chances of multiple flash floods, caused by debris blocking the river and in forming artificial lakes.

Khuruthang residents were moved to Woolakha and Bajo residents to Gangtey Thangkha, the old Wangdue town.  All patients of Bajo hospital were also moved to Tencholing military hospital. After more than an hour, the sirens, which created panic among residents, were also turned off.

Gasa dzongkhag officials, who moved to Gasa Tshachu since 6.30pm were still at the tshachu monitoring the water level when this paper went to print at 11.50pm.

A state of panic washed over the people of Punakha and Wangdue valley yesterday evening as word of incessant rain over the last three days caused Shinchila Tsho (lake), also known as Lemthang Tsho in Laya to burst.

Within hours, early warning sirens went off down stream, putting residents on alert to be ready for evacuation any time.

At 9.37pm, Prime Minister Tshering Tobgay tweeted saying that the first possible of two floods on Mochu reached Tashithang in Punakha. “Water level is dangerous. Immediate evacuation along Mochu and Punatsangchu compulsory,” he tweeted.

By 10.30pm, disaster management director Chhador Wangdi, who was at the  early warning control room at the hydro-met office said all residents of the two dzongkhags were evacuated to safety.

Along with him, the prime minister, economic affairs minister and hydro-met officials were also at the control room last night monitoring the situation.

“The second flood was expected to reach Punakha by 11.30pm,” he said. “Rain has subsided in Laya and by the time the water reaches downstream, the current would have subsided but we are still monitoring.”

Laya Gup Gyem Tshering said it was the cordycep collectors in Laya who first called him to inform about the outburst of Lemthang Tsho, one of the many sources for Mochu. 

The lake, according to gup Gyem Tshering is about three hours walk from Laya gewog.  “We have alerted everyone including Punakha and Wangdue district officials, police, hospital, town representatives and Punatsangchu project officials,” he said.

Around 10.30pm, home minister Damcho Dorji informed on Facebook that the lake at Shinche La, which takes about 45 minutes to walk around, has burst totally emptying all its water into the Mochu.

There are about 40 temporary settlements near the lake currently with people collecting cordyceps as well as yak herder camps. “No human casualty has been reported but there may be animal deaths, especially yaks and horses grazing downstream in the plains,” he said.

Early last night, the flood siren system at Taktsi Makhang recorded 6.5 metres. The alert level there is 7.5. Only when the water level crosses the ‘alert’ mark will the machines read the threat as ‘alarming’. However, not all siren systems will have the same alert and alarm levels due to gradient and topography of places.

The system at Tashithang, had however, crossed the 8.5 metre alert level. Engineer with the hydro-met services department, Sangay Tenzin, said people along the Mochu have been alerted and all the siren systems activated.

There are three flood siren systems along the Mochu– one in Taktsi Makhang, and other two in Tashithang and Yebesa.

Environment officer with Punatsangchu project, Sangay Dorji said the height of the water at the diversion tunnel measured at more than 8 metres and 3.4 metres at Wangdue bridge.

“We have been informed about the outburst at 6:35pm, and we have already alerted our contractors and labours at the project site,” he said, adding all people have been mobilised and on detecting the slightest danger, an evacuation would proceed.

The officials were expecting the first flow of the burst to reach Wangdue by 9.30pm. “However, since we don’t know the intensity of water we are going to receive, we don’t know the amount of risk we are going to face.”

Sonam Pelden and Dawa Gyelmo