A multi-dimensional analysis of pro-glacial landscape change at Sólheimajökull, southern Iceland

Proglacial landscapes are some of the most active on Earth. Previous studies of proglacial landscape change have often been restricted to considering either sedimentological, geomorphological or topographic parameters in isolation and are often mono-dimensional. This study utilised field surveys and digital elevation model analyses to quantify planform, elevation and volumetric proglacial landscape change at Sólheimajökull in southern Iceland for multiple time periods spanning from 1960 to 2010. As expected, the most intense geomorphological changes persistently occurred in the ice-proximal area. During 1960 to 1996 the proglacial river was relatively stable. However, after 2001 braiding intensity was higher, channel slope shallower and there was a shift from overall incision to aggradation. Attributing these proglacial river channel changes to the 1999 jökulhlaup is ambiguous because it coincided with a switch from a period of glacier advance to that of glacier retreat. Furthermore, glacier retreat (of ~ 40 m.yr-1) coincided with ice-marginal lake development and these two factors have both altered the proglacial river channel head elevation. From 2001 to 2010 progressive increase in channel braiding and progressive downstream incision occurred; these together probably reflecting stream power due to increased glacier ablation and reduced sediment supply due to trapping of sediment by the developing ice-marginal lake. Overall, this study highlights rapid spatiotemporal proglacial landscape reactions to changes in glacial meltwater runoff regimes, glacier terminus position, sediment supply and episodic events such as jökuhlaups. Recognising the interplay of these controlling factors on proglacial landscapes will be important for understanding the geological record and for landscape stability assessments.