Influence of a fine debris layer on the melting of snow and ice on a Himalayan glacier

The effect of a thin layer of fine debris on the melting of snow and ice was investigated over Dokriani Glacier at an altitude of about 4000 m in the Garhwal Himalayas (31 degrees 49 -31 52 N, 78 47 -78 51 E). Such investigations were made during summer 1995, 1997 and 1998. The average melt rate with respect to unit temperature or degree-day factor for clean and dusted snow was computed to be 5.8 and 6.4 mm degreesC(-1) day(-1), whereas for clean ice and debris-covered ice the value of this factor was 7.3 and 8.0 mm degreesC(-1) day(-1), respectively. Melt rate of clean ice was about 1.26 times greater than that for clean snow under similar weather conditions. The effect of debris layer on the melt rate of snow was more prominent than that for ice. The presence of debris on the ice increased the melt rate by about 8.5%, whereas for snow it increased by about 11.6%. Information on such factors is useful for runoff modelling of glacierized drainage basins.