The dynamics of supraglacial ponds in the Everest region, central Himalaya

Abstract

The dynamics of supraglacial pond development in the Everest region are not well constrained at a glacier scale, despite their known importance for meltwater storage, promoting ablation, and transmitting thermal energy englacially during drainage events. Here, we use fine-resolution (~0.5–2m) satellite imagery to reveal the spatiotemporal dynamics of 9340 supraglacial ponds across nine glaciers in the Everest region, ~2000–2015. Six of our nine study glaciers displayed a net increase in ponded area over their observation periods. However, large inter- and intra-annual changes in ponded area were observed of up to 17% (Khumbu Glacier), and 52% (Ama Dablam) respectively. Additionally, two of the fastest expanding lakes (Spillway and Rongbuk) partially drained over our study period. The Khumbu Glacier is developing a chain of connected ponds in the lower ablation area, which is indicative of a trajectory towards large lake development. We show that use of medium-resolution imagery (e.g. 30m Landsat) is likely to lead to large classification omissions of supraglacial ponds, on the order of 15–88% of ponded area, and 77–99% of the total number of ponds. Fine-resolution imagery is therefore required if the full spectrum of ponds that exist on the surface of debris-covered glaciers are to be analysed.