Hydrological and meteorological observations of river runoff, precipitation and air temperature were conducted 27 August to 26 October 1982, in Langtang Valley, Nepal Himalaya, whereby the mass balance of the glacier system there was estimated. Observed values suggest that (1) all glacier ablation and rainwater in the subwatershed of Langtang Valley drain into the river with the runoff coefficient of 1; (2) ablation of the glacier system can be estimated simply using a degree-day factor of 10

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... /degree-day; and (3) precipitation is considered uniform over the whole watershed. Assuming that the suggested phenomena persist throughout the year, records of monthly precipitation and monthly mean temperature in this valley, indicate that annual accumulation and ablation in the glacier system amount to 2000 ± 200 mm, respectively.