thayyen_2005.htm

Bulletin of Glaciological Research 22 (2005) 31-37
©Japanese Society of Snow and Ice

Slope lapse rates of temperature in Din Gad (Dokriani Glacier) catchment,
Garhwal Himalaya, India

Renoj J. THAYYEN, J.T. GERGAN and D.P. DOBHAL
Wadia Institute of Himalayan Geology, 33-GMS Road, Dehradun, 248001, India
email: renoj@rediffmail.com
 

Abstract

　Temperature lapse rate studies of Din Gad catchment in Garhwal Himalaya were carried out during the ablation period (May-October) in 1998, 1999 and 2000. Temperature data for this study was collected from the meteorological stations established at three altitudes (2540, 3483 and 3763 m a.s.l.) in the Din Gad catchment This data has been analysed to determine suitable lapse rate of slope temperature for temperature index modeling of snow/glacier runoff and mass balance of Dokriani glacier. Station pair within the alpine zone (3483 and 3763m a.s.l.) of the catchment shows distinct variations in lapse rate as compared to the valley scale (2540 and 3763m a.s.l.) lapse rate. Yearly variations in the lapse rate within the alpine zone of the catchment were higher than the variations of valley scale lapse rate, which show 40-50% reduction in the lapse rate in 1999 and 2000 as compared to 1998. It is also observed that in the valley scale, lapse rate values were lower during the monsoon months, compared to the rest of the ablation months. However this trend is absent between the station pair located within the alpine zone. Due to non-linearity of lapse rate of Din Gad valley as observed in this study, it is suggested that the lapse rate of the alpine zone is most representative of the glacier catchment, suitable for snow/glacier melt runoff and mass balance models. It is suggested that the lapse rate of alpine zone of the catchment have to be monitored for modeling hydrological processes of Himalayan glaciers, rather than adopting the lapse rates of mountain areas of other geographical locations or extrapolating lapse rate values of lower elevations of the Himalayas, as being practiced today.