Glacial runoff characteristics of the Koxkar Glacier,Tuomuer-Khan Tengri Mountain Ranges,China

This paper presents the glacial runoff characteristics of the Koxkar Glacier, China using flow records collected near the snout of the glacier in four consecutive years (2005–2008). The mean annual discharge of the Koxkar Glacier is 102.86 × 10⁶ m³, in which 93.6% occurs in ablation season (May–October). August brings about maximum discharge of about 29.6% to the total streamflow followed by July of some 26.0%. During the study years, total discharge varies little from year to year, whereas the inter-annual variability in monthly discharge is prominent, particularly in the beginning and in the end of the melt season. Seasonal runoff variability shows great monthly variations in discharge with mean coefficient of variation ranging from 0.02 in January to 0.77 in April. The mean diurnal amplitudes are found to be 0.90, 1.86, 4.71, 4.92, 1.17 and 0.43 m³ s⁻¹ for May, June, July, August, September and October, respectively. In the melt season, the maximum runoff is observed during 1800–0200 hours and the minimum occurs during 0700–1000 hours. Delaying effects are prominent in discharge over the ablation period. The time-lag between meltwater generation and its appearance in the streamflow near the snout of the glacier varies between 4.00 and 10.00 h, and time to peak varies between 10.00 and 17.00 h over the entire melt season. The relationship between discharge and temperature on monthly scale (R ² = 0.77) is better than that on daily scale (R ² = 0.55).