THE CHONG KUMDAN GLACIER 1932

Lieut.-Colonel KENNETH MASON

On the 12th July 1932 the upper Shyok glaciers once more attained notoriety in the world press; but only for a day and before the type was set the danger was over. The Chong Kumdan glacier behaved very much as had been anticipated, and the dam did not survive till August.¹ During the 9th July the waters scoured a tunnel under the ice which had become weakened by degeneration, and the ice continued to collapse throughout that day and the next. The lake appears to have taken nearly three days to escape, and no great damage was done.

Captain Gregory, whose interesting account of the glacier's condition appeared in the Himalayan Journal last year, was in Ladakh during the summer of 1932 and has sent me notes which he made after a conversation with Mr. T. Durgi, the Public Works sub- overseer in charge at Leh, together with a photograph of the glacier from downstream taken after the waters had escaped. Mr. Durgi was sent up to report on the condition of the ice towards the end of June. He first visited the snout from downstream, but was unable to climb on to the glacier. He therefore wisely made the detour by the Depsang Plains, and camped at the northern edge of the lake, where from observations to Mr. Gunn's cairns he calculated that the lake-level was 37 feet below the high level of 1929.² On returning by Murgo to the Shyok valley, Mr. Durgi found that the water was abnormally high in the tributary three miles from Saser Brangsa on the evening of the 9th July, and he camped on a ledge above the water-level. Early the next morning he reached the Shyok river at Saser Brangsa and found it 'very high'; he does not say how high, but he records that it was only with the greatest difficulty and with the assistance of the trained ford-guards that he was able to cross the river at about 10 a.m. The guards said that the water had begun to rise early in the morning, but it is probable from Mr. Durgi's experiences in the tributary that active percolation through the glacier had begun the day before.

Mr. Durgi then made his way up the Shyok valley and reached Aktash at 2 p.m., where he ascertained that the barrier must have already broken. He records that the highest flood-level appeared to be at 11.30 a.m. on the 10th July, that the water remained at that level until 2 p.m. on the 11th, that is, for over 26 hours, and that the level during that period was about 12 feet, as far as he could judge, below the highest level of 1929.

These figures are somewhat difficult to reconcile with those received from the authorities at Khalsar, Skardu, and Bunji, and an attempt is made below to discuss them. Mr. Durgi was lucky to cross the Shyok at Saser Brangsa at 10 a.m. on the 10th. At the end of June or in early July, when the dam is intact, there is only about a foot of water at the deepest part of the Brangsa ford, but the crossing is liable to be difficult owing to the formation of quicksands; the ford-guards are stationed here for the express purpose of reconnoitring the best line and assisting caravans. The river is wide at this point, but a rise of four feet would have rendered it unfordable to man or beast. It seems to me certain that though percolation through the glacier was now going on rapidly, nothing in the nature of a catastrophic burst had occurred; at the time of crossing Mr. Durgi was uncertain whether the dam had broken or not.

Later Mr. Durgi made his way as close as possible to the Chong Kumdan glacier, but owing to the formation of a large lake below it he could not get very close. He could, however, observe that the lake had emptied through percolation under the ice and not by a clear-cut channel as in 1929. The tunnel was about 450 feet wide, and from his photograph it is obvious that it occurred approximately at the same spot where the burst occurred in 1929; on that occasion the breadth of the channel was estimated by Mr. Gunn at 400 feet. Unfortunately Mr. Durgi's photograph was not taken from the same spot as Mr. Gunn's, so it is not possible to say definitely whether the line of weakness has moved forward between 1929 and 1932; but it is clear that the surface and downstream side of the glacier has undergone considerable deterioration since 1931. Mr. Durgi records that before he left 'the lake was empty and the waters of the Rimo glacier and the Chip Chap river were passing down the centre of the bed of the old Shyok lake and under the ice of the glacier'.

As soon as Mr. Durgi discovered that the lake was escaping the dispatched coolies post-haste to warn Khalsar, 135 miles by river below the dam. These men covered the difficult cross-country journey of about eighty miles in 28 hours and reached Khalsar about 7 p.m. on the nth. They were, however, beaten by the flood, which appears to have reached its peak at that place at 3 a.m. that morning, 16 hours before them. At Khalsar there is a gauge and a telephone line to Leh. The Tahsildar at Leh telegraphed on the morning of the nth as follows: 'Shyok dam reported burst on nth July at 3 a.m. when water reached 50 feet above zero. It fell down to 40 feet at 4 a.m. and to 35 feet at 5 a.m. and came to 31 feet at 5.30 a.m.⁵

The Wazir at Skardu, 310 miles from the dam, where the next gauge is fixed, however wired the same afternoon as follows: horning gauge at Skardu 14 feet. At 1420 hours water seen rising. At 1800 hours gauge reads 32-2. Tahsildar Leh wired just now Khalsar gauge reader reports Shyok dam burst at 3 a.m. to-day: Flood coming.⁵

It is obvious that the Khalsar gauge-reader could not know at what time the Shyok dam gave way until the dispatch coolies sent down by Mr. Durgi reached that place at 7 p.m.; and at the time he reported to Leh and Skardu he could only record what had occurred at Khalsar. It seems to me almost certain that the Khalsar gauge- reader's evidence is that the high flood was reached at that place about 3 a.m. The peak may have been reached actually before that hour for the readings of the gauge after 3 a.m. indicate that the river level fell 10 feet during the next hour.

Assuming that 3 a.m. is the time of the passing of the peak by Khalsar it is interesting to compare the passage of the flood in 1932 with that of 1929.

If the peak reached Khalsar before 0300 hours on the 11th as suggested above, the figure 8-7 above would be too low, and 1o.1 too high. The rates of the passage of the peak of the 1929 flood between Khalsar and Skardu, and between Skardu and Bunji were 12.5 and 13.7, an indication of the more violent nature of that burst.

The approximate rises of the water at these places are also interesting to compare. At Khalsar the river only rose 45 feet against 63 in 1929; at Skardu 18 (1932) against 25 (1929); at Bunji 30 (1932) against 35 (1929).

The time taken for the river to rise to peak level at Khalsar is not known, for the river apparently began to rise during the night when no one was on duty at the gauge. At Skardu it took about 5 ½ hours and at Bunji about 16 hours to reach peak level; these figures may be compared with 3 ½ and 8 hours in 1929. All these comparisons taken together make up a mass of evidence to prove the comparative gentleness of the 1932 flood.

Captain Gregory reports that the only loss of life he heard of was at Khalsar, where an old ferry boat was launched too soon and before the flood had subsided. The boat was carried down on to the rocks and smashed to bits, the six occupants being drowned. The suggestion made in certain engineering circles to tunnel by-passes for the waters upstream through the solid rock against which the Chong Kumdan glacier impinges, in order to prevent the formation of the glacier lake, is an interesting theoretical consideration of no practicable application. The cost of such an undertaking would be more than that required to move all the inhabitants from all the possible danger zones down the course of the river and to maintain them elsewhere in plenty and comfort.

From a study of all the evidence available it does not seem probable that the dam will heal again during the winter of 1932-3; at the time of going to press we have received no recent reports. This statement does not mean that the caravan route along the valley will immediately become practicable; it will probably take a few years before there is a clear passage down the valley, and it is then possible that the Kichik Kumdan glacier will have advanced sufficiently to block the way, though not the valley. It appears to me that all through the remainder of July last year and the whole of August, the intense ablation at the snout, assisted by erosion from the flood waters of the melting Rimo glacier, will have widened the tunnel and caused the surface to fall in; and if there is any regularity in the snout movement of this glacier, as there seems most certainly to be, there can be no factor which would tend to heal the glacier.

In this connexion it seems relevant to call attention once more to the constant error made by continental observers of Karakoram and Himalayan glaciers. Glaciers in the Alps have been studied now for some years, and it is said, and apparently accepted, that the seasonal advance of most glaciers there is more rapid in the summer than in the winter months. It may be so, though I am personally not convinced of the truth of this assertion. The actual flow in the glacier is faster in summer than in winter; but this is a very different thing from seasonal snout variation, which is dependent also on ablation it the snout. That factor of snout ablation is a variable quantity. In the Alps it may be negligible as some of the continental records seem to imply; but in the Karakoram and Himalaya it is the dominant factor. There is not the slightest doubt that in the Karakoram any tendency for seasonal summer advance, caused by the increased velocity of the ice-stream in summer, is entirely overwhelmed by the intense ablation that occurs at the snout of all glaciers of any size in that region; and it is only when such a glacier is actively in periodic advance that it can overcome the intense ablation factors and hence the seasonal summer tendency to retreat. In August and September, therefore, when this intense ablation has been operating for some time we must expect to observe signs of retreat, and we must interpret those signs as normal seasonal phenomena and not as evidence of something strange. Similarly in winter, when there is no ablation whatever, the normal flow of the glacier-stream, however much retarded by the cold, must tend to promote active winter advance of the snout, and unless the glacier is in periodic retreat, it will show an upstanding active front. This is the simple explanation why glaciers in the Karakoram form their blocks in the winter and early spring, and burst as a rule during the late summer and early autumn months; and it accounts for the tendency to heal again in the winter succeeding a summer burst. But if a glacier bursts in early summer or before the period of intensive ablation has set in, say the end of July, then it is possible, and even probable, that the ablation will so deteriorate the ice that the winter will not heal it.

Continental observers coming to the Karakoram in August express surprise and frequently note that 'all the glaciers are retreating'; in the winter they are apt to be as much surprised because so many glaciers appear to be advancing.¹⁵ I maintain that there is nothing whatever to be surprised at in the Karakoram, where the seasonal factors are so pronounced as to overcome completely the comparatively small difference between the winter and summer velocities of the ice-stream, and to smother in many cases the periodic factors of advance and retreat.¹⁶

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