Figure 1: Time lapse video of the Ngozumpa glacial lake filling and draining over a fifteen day period (Source: Live Science, 7th December 2011).
Reflecting the general trend across the region, melting of the debris-covered Ngozumpa glacier in Nepal is of growing concern for scientists due to the rapid growth of the glacial lake at the glacier's snout. Named the 'Spillway', the glacial lake is equivalent in size to 40 Olympic swimming pools contained behind a terminal moraine dam (BBC News, 26th December, 2011). Although it is claimed the threat of a glacial lake outburst flood (GLOF) is less imminent than other glacial lakes, scientists are still monitoring changes in the dynamics of the lake. Using timelapse cameras, research by the Cooperative Institiute for Environmental Sciences (CIRES) have demonstrated dynamic fluctuations in the lake volume reflecting complex interaction of factors controlling inflow and outflow to the lake (Figure 1). Observations from the time-lapse cameras showed a decrease in volume by over 100,000m³ in two days, followed by a recovery of around half of this volume in the five days following this event (BBC News, 26th December 2011).
Although assessments of the Spillway suggest this glacial lake is less of an imminent threat to outburst compared to other glaciers in the region, the results from the timelapse videos demonstrate the complex interaction of factors controlling the growth of glacial lakes in the Himalayas. Beyond a basic understanding of the relationships between glacial lake growth and glacier melt this research highlights our limited understanding of the mechanisms regulating volume within these glacial features. Coinciding increased rates of glacial melt due to climate change, the frequency of GLOFs are increasing. Thus understanding the dynamics behind the formation and regulation of lake volume, being undertaken in studies such as this is becoming increasing important.
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