Female porters of the Tamang tribe near Tangnag, background broken moraine dam of the Sabai Tsho Lake.
Last night I had a splitting headache by the high altitude. We went from 2900 m to 4600 m in only 4 nights and the trails on the mountain range were rough but very scenic.
Yesterday we could not use the normal, low and easy trail from Thuli Kharka to Tangnag as it was washed out by a large flood but the Sherpas couldn't tell me what really happened. The alternative upper trail was really poor and normally only used by yaks to migrate to summer pastures high up in the mountains, up to 5000 m. We even had to use a rope at a steep, rocky part once.
Today, in the early afternoon, we finally went down into the main valley and Mart was elated, photographing various colorful flowers.
Small white flowers grew everywhere and as soon as you left the trail you could not avoided stepping on them. During rest breaks and 'pipi machen', I must have squashed several. Mart had to tell me that these were Edelweiss flowers and after some disbelieve I collected a few.
Hinku valley downstream, destructive flood visible in riverbed (white rocks). Edelweiss flowers in the foreground.
Phurba Sherpa, our Sirdar, said that this valley was known for its Edelweiss flowers, left untouched by the yaks as they do not like the tough, nettle like stem. A Japanese man was known to come here once a year to collect 2 suitcases but this is illegal. Even the few Mart and I picked could get us into trouble.
On the way down, I was carefully observing the river valley and already from a large distance you could tell a destructive flood rushed through the valley recently, see picture above. Finally down in the river valley I could assess the scale of the flood. In places the wall of water must have been 200 m wide and 10 m high or 100 m wide and 20 meters high, destroying the riverbed and main trail in several places. This was visible on the bushes and gravel deposits. Close to Tangnag, we finally saw the source of the flood.
Sabai Tsho Lake, view from a helicopter, lake 0.5 km wide.
The Sabai Tsho Lake which is a half square km in size, had a gaping hole in the 100 high moraine dam and the lake level dropped by 50 m. After the dam burst, the lake must have dropped in a matter of minutes. The enormous amount of water released made a devastating trail up to 500 m wide near Tangnag carrying boulders of up to 1 m. Only the biggest rocks, some 3-5 m across, seemed to have hardly moved.
This was a very recent glacial lake outburst flood and somehow the natural moraine dam broke. As it was the end of the monsoon season, we suspected heavy rain in August or early September but we would find out soon after arriving in Tangnag, see below.