Glacier Lake Bursts in Bhutan

Bhutan Times - - Editorial -

On the morn­ing of Sun­day 28 June, an earth­quake in In­dia caused a Gla­cial Lake Out­burst Flood in north­ern Bhutan. Lo­cal res­i­dents alerted of­fi­cials, who ac­ti­vated warn­ing sys­tems and or­dered evac­u­a­tions down­stream. Rivers rose to high lev­els, but no fa­tal­i­ties oc­curred. By Mon­day night, the rivers had be­gun to fall.

The United States Ge­o­log­i­cal Sur­vey re­ported an earth­quake of 5.5 on the mod­i­fied Richter scale at 7:05 AM lo­cal time, at 17km north­north­east of the town of Ba­sugaon, in As­sam State, In­dia and 22 km south of the town of Gele­phu in Sarpang Dis­trict, Bhutan.

Light to mod­er­ate shak­ing was re­ported from Nepal and Bangladesh as well as Bhutan and In­dia. Sonam Cho­den in Thim­phu in western Bhutan re­ported on Face­book “the earth­quake rocked my hus­band right back on to sleep­ing.” San­gay Wangchuk, who lives in Jakar in cen­tral Bhutan, wrote “Ap Naka wags its tail again.” Ap Naka means “fa­ther earth­quake,” re­fer­ring to the com­mon belief that the earth is held by a gi­ant male spirit whose move­ments cause earth­quakes.

The im­me­di­ate dam­age in Bhutan was neg­li­gi­ble, and even in In­dia it was slight. Three per­sons sus­tained mi­nor in­juries when an old wall col­lapsed near the rail­way sta­tion in Kokra­jhar, As­sam, in­jur­ing three peo­ple. At an an­cient tem­ple in Chi­rang dis­trict, As­sam, a sculp­ture of a lion was knocked off its base.

A gla­cial lake, Lemthang Tsho, lo­cated about 95 km north­west of the epi­cen­ter, burst later that day. This lake, also known as Shin­chila Tsho, is lo­cated in Laya County in Gasa Dis­trict in north­ern Bhutan, close to the bor­der with China. Ac­cord­ing to Kuensel, Kin­ley Dorji, a county of­fi­cial in Laya, stated that mush­room col­lec­tors in the high pas­tures near glaciers had called him to let him know about the out­burst from the lake, which is one of the sources of the Mochu, a ma­jor river of Cen­tral Bhutan. He, in turn, alerted dis­trict of­fi­cials in Gasa and in Pu­nakha and Wang­due, two large dis­tricts down­stream on the Mochu. He also spoke with po­lice, hos­pi­tals and of­fi­cials at a large hy­dro­elec­tric sta­tion at Pu­natsangchu.

Of­fi­cials at the three ma­jor gauges along the Mochu­mon­i­tored the wa­ter lev­els closely. They be­gan sound­ing the sirens around 6:30 pm, even be­fore the rivers reached the level for alerts, be­cause they were con­cerned about ad­di­tional risks from the mon­soon rains, which had been heavy dur­ing the pre­ced­ing weeks. The sirens caused panic among many res­i­dents, and they were turned off af­ter more than an hour. The Prime Min­ster or­dered evac­u­a­tions along the Mochu River and at the hy­dropower sta­tion at 9:30pm, and re­ports sug­gest that these were largely com- plete within an hour. Pa­tients at a hos­pi­tal close to the river were moved to a mil­i­tary hos­pi­tal at higher ground.

The river peaked late that evening, with high wa­ters at Pu­nakha a bit be­fore mid­night and at Wang­due later on. For­tu­nately, the towns were not dam­aged. The his­toric fortress or dzong of Pu­nakha had been par­tially de­stroyed by a glacier lake out­burst flood in 1994, so res­i­dents were con­cerned. The res­i­dents re­turned to their homes the next morn­ing. Power, which had been cut in Pu­nakha, was also re­stored. Teams trav­eled through the area on 29 and 30 June to ex­am­ine the dam­age. Theyre­ported that six wooden bridges had been washed out, iso­lat­ing some vil­lages and Laya town, and im­ped­ing the as­sess­ment ef­forts. Sev­eral groups of mush­room col­lec­tors were stranded on the far side of the now-empty Lemthang Tsho lake.

Karma Dupchu , the chief of the Hy­drol­ogy Di­vi­sion within Depart­ment of Hy­drom­e­te­o­rol­ogy, will send a del­e­ga­tion to the glacier lakes high in the Mochu drainage, to see which of them burst, and to as­sess the rel­a­tive im­por­tance of the earth­quake and the heavy rains in caus­ing the flood.

Re­build­ing ef­forts al­ready be­gan by 30 June, as shown by a tweet from the Prime Min­is­ter Tsh­er­ing Tob­gay.

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