3. An Inventory of Proglacial Systems in Austria, Switzerland and Across Patagonia

Deglaciation since the Little Ice Age has exposed only a small areal proportion of alpine catchments, but these proglacial systems are disproportionately important as sediment sources. Indeed sediment yields from proglacial rivers are amongst the highest measured anywhere in the World. Motivated by a desire to understand where exactly within catchments this sediment is coming from and how it might evolve, this chapter presents the first digital inventories of proglacial systems and the first comparative inter- and intra-catchment comparison of their geometry, topography and geomorphology. Whilst focussing on the description of these inventories and on descriptive statistics, it highlights the potential of these data, with examples from Austria, Switzerland and Patagonia, for interpreting landscape evolution status, predominant earth surface processes and glacial meltwater inundation patterns. Switzerland has by far the highest proportion of very small (<0.5 km²) proglacial systems. Patagonia has the most even distribution of proglacial systems in terms of areal size and elevation above sea level. We found no east–west or north–south spatial pattern in geometric or topographical metrics, such as hypsometric index, thereby refuting a straightforward control of climate-driven precipitation or air temperature. However, we note that geology, particularly rock hardness, could be a major factor in proglacial system character. Likely sediment sinks can occupy up to ~30 and 20% of proglacial systems in Austria and Switzerland, respectively, but up to 90% of those in Patagonia where many systems terminate on a coastline. Meltwater influence maps and landform maps, derived from contributing area and slope data, respectively, will not only be useful for many environmental science disciplines but also for water resources, landscape managers and natural hazards authorities. Overall, this chapter presents an objective and easily implemented method for making proglacial systems inventories and for characterising inter- and intra-catchment geomorphological form and function.