Hydrological characteristics of the Gangotri Glacier, central Himalayas, India

SummaryThe present study describes the hydrological characteristics of the Gangotri Glacier (286 km2), which is one of the largest Himalayan Glaciers. The study involves collection and analysis of streamflow records near the snout of the Gangotri Glacier during four consecutive ablation seasons (May–October) (2000–2003). Discharge increases from May onward, reaches its highest value in July and then starts decreasing. Daily mean discharge during the study period varied between 8 and 194 m3 s−1. The distribution of runoff has shown that July contributes maximum runoff (30.2%) followed by August (26.2%). Maximum diurnal variability in runoff was observed in the month of May and September. The strong storage characteristics of the study glacier are reflected by a comparable magnitude of runoff observed during daytime and nighttime. Diurnal variations in hydrograph suggested almost similar pattern from year to year, being maximum runoff in the evening and minimum in the morning. Melt-runoff delaying characteristics reflected that over the melt season time lag (tl) varied between 4.00 and 7.30 h, whereas time to peak (tp) varied between 9.00 and 12.30 h. Relationship between mean monthly discharge and temperature was found to be much better (R2 = 0.76) than that on daily scale (R2 = 0.50).