Understanding the interrelationships among mass balance, meteorology, discharge and surface velocity on Chhota Shigri Glacier over 2002-2019 using in situ measurements

Abstract

The Himalayan glaciers contribute significantly to regional water resources. However, limited field observations restrict our understanding of glacier dynamics and behaviour. Here, we investigated the long-term in situ mass balance, meteorology, ice velocity and discharge of the Chhota Shigri Glacier. The mean annual glacier-wide mass balance was negative, -0.46 ± 0.40 m w.e. a-1 for the period 2002-2019 corresponding to a cumulative wastage of -7.87 m w.e. Winter mass balance was 1.15 m w.e. a-1 and summer mass balance was -1.35 m w.e. a-1 over 2009-2019. Surface ice velocity has decreased on average by 25-42% in the lower and middle ablation zone (below 4700 m a.s.l.) since 2003; however, no substantial change was observed at higher altitudes. The decrease in velocity suggests that the glacier is adjusting its flow in response to negative mass balance. The summer discharge begins to rise from May and peaks in July, with a contribution of 43%, followed by 38% and 19% in August and September, respectively. The discharge pattern closely follows the air temperature. The long-term observation on the 'Chhota Shigri - a benchmark glacier', shows a mass wastage which corresponds to the slowdown of the glacier in the past two decades. Copyright © The Author(s), 2020. Published by Cambridge University Press.