Abstract
This publication in Springer’s Geography of the Physical Environment book series reflects the increasing interest in proglacial areas (glacier forelands) as field laboratories for investigating the development of alpine and polar landscapes and their associated geo-environmental and geo-ecological processes and systems. A proglacial area, glacier foreland or glacier forefield is conventionally defined as the landscape that has developed following the retreat of a glacier from its ‘Little Ice Age’ maximum extent attained no more than a few centuries ago. Such landscapes are increasing in extent as glaciers continue to shrink in response to climate change in general and global warming in particular. Their prime methodological advantage in the context of the natural environmental sciences is the relative simplicity of their hydrological, geomorphological and ecological processes and systems, which have been developing for only a few hundred years. They contrast, therefore, with most other landscapes on the Earth’s surface characterised by complex interactions, a long history of development and greater anthropogenic inputs.
In Geomorphology of Proglacial Systems, the editors have brought together a wide range of studies on proglacial areas with a focus on landforms and sediment dynamics, mainly in the European Alps. In the introduction, it is pointed out that the inspiration for the book was the German/Austrian PROSA project (high-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) conducted from 2012 to 2017 in the proglacial area of the Gepatschferner in the Austrian Alps. Several case studies presented in the book derive from that project, the research objective of which was to establish a holistic sediment budget for the proglacial area, including sediment fluxes, storage and yield in relation to glacier dynamics, fluvial processes and the different mass movement processes. The book is also intended as an update and complement to the existing literature on proglacial areas and paraglacial dynamics, from which Matthews (1992), Hewitt et al. (2002), Ballantyne (2002) and Knight and Harrison (2009, 2014) are highlighted.
The book contains five parts: (1) glaciers and ground ice in the proglacial zone (six chapters); (2) proglacial hillslope process (four chapters); (3) proglacial rivers and lakes (three chapters); (4) proglacial sediment cascades and budgets (three chapters) and (5) the role of soil, vegetation and morphodynamics in the evolution of proglacial systems (two chapters). Particular chapters vary from broad-ranging reviews of methods and findings to detailed case studies of particular sites. The book is therefore well focused on the geomorphological dynamics of glacier forelands, does not deviate very far from the central theme and provides an interdisciplinary perspective of interest to physical geography, geology, glaciology, geophysics and even biology.
Part 1 includes contributions on glacier variations since the ‘Little Ice Age’ (Paul and Bolch), glacier-foreland inventories of Austria, Switzerland and Austria (Carrivick et al.), debris-covered glaciers (Mayr and Hagg), ice, water and sediment fluxes at the terminus of Gepatschferner (Stocker-Waldhuber and Kuhn), proglacial ground ice in front of Swiss glaciers (Gärtner-Roer and Bast) and permafrost morphodynamics in the Upper Kaunertal (Dusik et al.). These chapters have glacial, paraglacial and periglacial aspects, ranging from the ground-based and satellite monitoring of glacier behaviour and the implications of continuing glacier retreat, to debris transport by glaciers and relationships between glaciers, ground ice and rock glaciers.
Part 2 includes a review of rock slope instability (McColl and Draebing) and chapters on rockfall from proglacial rockwalls in the Kaunertal (Vehling et al.), glacial sediment stores and their reworking (Porter et al.), and slope wash, gully erosion and debris flows on lateral moraines (Dusik et al.). Here paraglaciation is the dominant theme, including the conditioning of rock slope failure and the erosion of unconsolidated sediments on terrain previously covered by glaciers. Implications discussed include the long-term effects on the landscape of glacio-isostatic adjustment following the Last Glacial Maximum, and likely hydrological changes and changes in sediment yields in response to future environmental change.
Part 3 begins with a summary of current knowledge on the monitoring and dynamics of sediment transport in proglacial rivers (Mao et al.). It also includes a case study of fluvial sediment transport (bedload and suspended load) in the glacier-fed Fagge River (Morche et al.) and a general review of proglacial lakes in high-mountain environments (Otto). Short-term monitoring methods and observed dynamics of sediment transport are emphasised in the former two chapters, while proglacial lakes are classified and discussed in relation to geomorphological impacts, natural hazards and socio-economic dimensions (particularly involving future water deficits).
Part 4 starts with a review of sediment budgets in high-mountain areas (Hilger and Beylich), followed by more specialised surveys of sediment connectivity in proglacial areas (Cavalli et al.) and a case study of the sediment budget of the Upper Kaunertal (Hilger et al.). This is perhaps the core of the book in that it focuses on obtaining an integrated understanding of geomorphological processes in proglacial areas through the concept of a sediment budget and the related concepts of sediment connectivity and sediment cascades. Although considerable progress is clearly being made towards a comprehensive approach to the quantification of sediment budgets, there are several important missing dimensions to such studies, including (1) the extent and role of chemical weathering and solutional transport, (2) scaling-up to the regional scale and (3) extension of the approach to longer timescales, including the Holocene.
Part 5 contributes chapters on the development of proglacial soils (Temme) and vegetation succession and biogeomorphic interactions in glacier forelands (Eichel). These chapters go some way towards a fourth missing dimension, at least in terms of obtaining a complete understanding of the proglacial geo-ecological system. Eichel’s chapter is a significant contribution in this respect, focusing as it does on the reciprocal role of disturbance in vegetation succession and the effects of plants on geomorphological processes. Such biogeomorphic interactions are effective influences on the development of patterned ground, glaciofluvial floodplains and moraine slopes. Whereas such interactions may be minor in the pioneer zone, where geomorphological instability is likely to be the dominant factor, plants soon cover the ground surface, affecting stability, surface transport and erosion. As stability increases, ‘ecosystem engineers’ become established and feedbacks become effective between later colonisers and geomorphological activity.
In summary, Geomorphology of Proglacial Systems represents a significant contribution to a developing area of geomorphology. The book provides a useful state-of-the-art survey of the geomorphological processes and dynamics of glacier forelands, which complements both recent journal articles in this field (e.g. Carrivick and Heckmann, 2017; Heckmann et al., 2016) and the longer history of ecological studies in such areas. It should be of considerable interest not only to geomorphologists but also to a wide range of natural environmental scientists seeking to understand processes in the landscape and/or reconstructing environmental change in cold climates, including readers of The Holocene.