And in this connection I would point out that the water-level of Tibetan rivers and lakes is subject to periodical fluctuations, dependent on the precipitation, of the same kind as the Brückner periods. The level in the two lakes varies from year to year. At the present time they are very low, but there is nothing to prevent them rising gradually in a more or less distant future. Tso-mavang may rise so that its water may again flow through the channel to Langak-tso, and this lake at length may discharge its surplus water, as formerly, through the dry bed of the Sutlej. It is more probable, however, that Langak-tso is approaching a time when it will lose its subterranean outlet also, and be quite isolated, like Gunchu-tso and Panggong-tso, and consequently become salt in time. But after it has lost its outlet it may be a long time, as Professor Brückner informs me, before the lake becomes noticeably salt. The next step in the development will be that Tso-mavang will be cut off from Langak-tso and likewise become salt.
However, we need not plunge into speculations and prognostications of the future, which may have surprises in store about which we can form only more or less probable conjectures. It is our duty to rely solely on fact and observation.
And now that we are agreed that the two lakes belong to the drainage area of the Sutlej, the question is: Which of the rivers debouching into Tso-mavang is the headwater of the Sutlej? Naturally, the longest and the one which carries most water. The river which once flowed out of Gunchu-tso has no claim to this honour, and the Gunchu-tso must be rejected as the source of the Sutlej. The Tage-tsangpo discharged 388 cubic feet of water per second, while all the other streams entering Tso-mavang carried at most 100 cubic feet each. The source of the Tage-tsangpo in the front of the Gang-lung glacier is therefore the source of the Sutlej.
[1] I have only omitted a couple of sentences, which have no immediate connection with the problem.
| 270. Tibetan Female Pilgrims at Kailas. |
CHAPTER LI
A PILGRIMAGE ROUND KANG-RINPOCHE