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

Pro-glacial landscapes are some of the most active on Earth. Previous studies of pro-glacial landscape change have often been restricted to considering either sedimentological, geomorphological or topographic parameters in isolation and are often mono-dimensional. This study utilized field surveys and digital elevation model (DEM) analyses to quantify planform, elevation and volumetric pro-glacial 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 pro-glacial 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 pro-glacial 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 ~40myr^-1) coincided with ice-marginal lake development and these two factors have both altered the pro-glacial 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 pro-glacial landscape reactions to changes in glacial meltwater runoff regimes, glacier terminus position, sediment supply and episodic events such as jökuhlaups. Recognizing the interplay of these controlling factors on pro-glacial landscapes will be important for understanding the geological record and for landscape stability assessments.