Assessment of periglacial response to increased runoff: An Arctic hydrosystem bears witness

Abstract

In the general context of global warming, the cryosphere appears as an environment that exhibits a strong sensitivity to climate variations. Overall, glacier systems are now known to be reliable indicators of climate trends. Although glacier dynamics are subject to international monitoring networks, periglacial environments are much less observed. However, these newly deglaciated areas get wider since glaciers are retreating, and their dynamics become increasingly significant. The observed increase in water fluxes, temperature and precipitation, permafrost melting, and reduced cold periods induce a combined control on modifications of the glacier and periglacial dynamics. Such consequences are also visible on the landscape, hinting at an adaptation of the environment to the climatic forcing. The work carried out focuses on Austre Lovénbreen area, a small 10‐km2 glacier basin (Svalbard, 78.87°N, 12.15°E, west coast of Spitsbergen) exhibiting typical arctic glacial retreat trends. Its geomorphological characteristics as well as its observatory status make it an appropriate control area. Our investigations are based on a combination of classical on‐site snow, ice, and geomorphological measurements, combined with innovative methods using aerial photography (e.g., from unmanned aerial systems) and digital photogrammetric image processing. Such data currently complement classical remote sensing methods (satellite imagery), providing both improved resolution and high temporal repeatability. Indeed, short acquisition time and flexibility allows measurements within very short time intervals, a requirement when short events are significant in the whole system evolution: The speed at which climatic change‐related events occur requires such fine‐grained spatial and temporal monitoring. This work highlights an increase of sediment transfers during the last decade that ties in with the increasing liquid precipitation as well as a trend of rising temperatures. The newly deglaciated area, particularly at the glacier front, is in constant and fast reshaping, which is quantifiable from 1 year to another, assessing the increase of periglacial landscape modification. This small‐scale detailed analysis enlightens on global processes occurring in Arctic regions demonstrating ongoing geomorphological and landscape changes as a consequence of glacier retreat and newly exposed periglacial environments.

Paraglacial coasts responses to glacier retreat and associated shifts in river floodplains over decadal timescales (1966–2016), Kongsfjorden, Svalbard

“…The intramorainic plains of Vestre, Midtre, and Austre Lovénbreen measured, respectively, 1.59, 2.61, and 2.51 km 2 in 2010. Sediments exposed by glacier retreat are being extensively reworked by runoff, which is the principal and most influential process in the formation of lowlands and slopes (Bernard, Friedt, Schiavone, Tolle, & Griselin, ; Orwin & Smart, , Mercier et al, ; Midgley et al, 2018). Furthermore, the retreat of glaciers has caused an increase in melt water volume.…”

Paraglacial processes in recently deglaciated environments

“…Thus, like Bernard et al (2018), they recognise the paraglacial period of heightened sediment delivery, but they also capture the slowdown of this period and reduction in sediment connectivity.…”

“…Fundamental to the transition from glacial to nonglacial environments is a change in the availability of water and sediment as hydrological regimes change and landscapes are exposed by retreating glaciers (Bliss, Hock, & Radić, ; Church & Ryder, ). In the forefield of a glacier in Svalbard, Bernard, Friedt, Schiavone, Tolle, and Griselin () offer a quantitative examination of such responses using repeat photogrammetry to measure the morphological changes and associated sediment remobilisation driven by contemporary glacier retreat, over a period between 1995 and 2016. Glacier retreat over this period exposed fresh and erodible glacial sediments and destabilised moraine, releasing paraglacial sediments to the forefield.…”

Snowcover Survey over an Arctic Glacier Forefield: Contribution of Photogrammetry to Identify “Icing” Variability and Processes

“…This quantity of snow partly explains the increase of water runoffs at the melting season. The potential release of a massive amount of water increases the sediment transfer, as observed in [37]. This analysis solves one of the missing variables in the hydrological equation, including the glacier area, which is the moraine area here, as well as the still missing slope contribution to the global hydrological budget.…”

“…Hence, the moraine exhibits features that are representative of successive retreats of the glacier with a particular shape at the interface with the glacier snout, due to the fast retreat during the last decade [35]. The combination of glacier melting, temperature variability, and increasing precipitation [36] widely favors processes, such as sediment transfer [37], melting, and runoffs [38]. Under these dynamics, the proglacial moraine constantly reshapes from one year to another due to the glacial retreat exposing brittle material in a rough topography.…”