水文学: 現在の研究

Winter Precipitation and Snowpack-melt with Temperature and Elevation at Solang Valley, India

Abstract

Anand Verdhen, Chahar BR1 and Sharma OP

Knowledge about variability of temperature, precipitation, snowpack and snowmelt with temperature and elevation are essential to prepare input data for hydrological models. The study presents characteristics and variability of these input variables during springtime at three elevations (Bhang, Solang and Dhundi stations in the Solang Valley of the western Himalaya) with respect to mean temperature (Tm) at Bhang using weekly data within a period of 27 years with initial (1982 and 1983) and later (2008 and 2009) consecutive years including decadal years 1993 and 2003. Methodology comprises of process integration using regression, simulation, cluster analysis, transformation, projection and inter-annual comparison. Study shows that temperature lapse rate (TLR) in stretches between snow-free to snow cover area (1.2°C/100 m) is more than the TLR in stretch of continued snow cover. Temperature, snowfall, rainfall and snow depth per 100 m of rise in elevation have been estimated as -1.09°C, 31.2 cm, -7.72 mm and 27.95 cm, respectively. The snowfall and rainfall mixed precipitation occurs within 0.65 and 11.5°C of weekly Tm for which distribution pattern has been developed. Temperature degree-day melt factors, determined in water equivalent term, vary between 2 and 11.5 mm°C-1d-1 and it may rise up to 13 mm°C-1d-1 for non-zero snow condition. The snow depth excess at Solang (2450 m amsl) in relation to Bhang (2190 m) has reduced by 50% over three decades while the snow depth excess at Dhundi (2950 m) from the snow depth at Bhang has increased by 15%. Furthermore, disappearance of the snow cover has been experienced earlier by 5 weeks in the region.