Effect of Meteorological Patterns on the Intensity of Streambank Erosion in a Proglacial Gravel-Bed River (Spitsbergen)

Abstract

Lower parts of proglacial rivers are commonly assumed to be characterised by a multiannual aggradation trend, and streambank erosion is considered to occur rarely and locally. In the years 2009-2013, detailed measurements of channel processes were performed in the Scott River (SW Spitsbergen). More than 60% of its surface area (10 km 2 ) occupies non-glaciated valleys. Since the end of the Little Ice Age, the Scott Glacier has been subject to intensive retreat, resulting in the expansion of the terminoglacial and paraglacial zones. In this area, the Scott River develops an alluvial valley with a proglacial river, which has led to a comparatively low rate of fluvial transport, dominance of suspension over bedload, and the occurrence of various channel patterns. Measurements, performed in the lower course of the valley in two fixed cross-sections of the Scott River channel, document variable annual tendencies with a prevalence of scour over deposition processes in the channel bottom. The balance of scour and fill also differs in particular measurement cross-sections and during the summer season. The maximum erosion indices (1.7 m 2 ) were related to single periods of floods with snow-glacier melt and rainfall origin. The contribution of streambank erosion was usually lower than that of deep erosion both in the annual cycle and during extreme events. The channel-widening index also suggests variable annual (from −1 m to +1 m) and inter-annual tendencies. During a three-day flood from August 2013, in a measurement profile at the mouth of the river, the NNW bank was laterally shifted by as much as 3 m. Annual and inter-seasonal indices of total channel erosion, however, show that changes in the channel-bottom morphology are equalised relatively fast, and in terms of balance the changes usually do not exceed 0.5% of a cross section's area.

Streambank Erosion: Advances in Monitoring, Modeling and Management

“…The research articles included in this special issue specifically targeted three areas that are key to better understanding streambank erosion and failure, namely, monitoring [8][9][10][11], modeling [12][13][14][15][16][17], and management [18][19][20][21]. As an ensemble, the articles highlight the value of monitoring campaigns to characterize the effect of external drivers (e.g., hydrologic events), the capabilities and limitations of numerical models for predicting the response of the system (e.g., stream restoration design), and the effectiveness of management practices to prevent and mitigate the impacts of streambank erosion and failure.…”

“…They developed a critical shear stress function that accounts for changes in soil moisture content for achieving a more accurate prediction of erosion zones within ephemeral gullies. Lastly, the study by Kociuba and Janicki [11] showed how highly variable hydro-meteorological conditions influence the contribution of bank erosion to total sediment load by measuring erosion rates at fixed locations using the Global Navigation Satellite System (GNSS).…”

Where will widening occur in an outwash braidplain? A new approach to detecting controls on fluvial lateral erosion in a glacierized catchment (north‐western Spitsbergen, Svalbard)

“…An accelerated rate of glacial ablation increases meltwater activity in the glacier forefield, where outwash (sandur) is incised into the pre-existing topography, and causes its degradation due to lateral erosion (Kociuba et al, 2014;Kociuba & Janicki, 2018;Strzelecki et al, 2018). The rate of this erosion depends on extreme ablationprecipitation events which control short-term modification of braidplain morphology and its extent (Beylich & Laute, 2015;Guillon et al, 2018;Kociuba & Janicki, 2018;Lane et al, 2017;Marren, 2005;Orwin et al, 2010;Rachlewicz, 2007). This erosion is related to the shifting of channels in the gravel-bed of the braided river in the area of steep braidplains that characterize outwash and alluvial fans in both proglacial and non-alpine settings (Ashworth & Ferguson, 1986;Nicholas & Sambrook Smith, 1998;Stock et al, 2007).…”

“…In many papers, different rates of lateral erosion have been reported (Ashworth & Ferguson, 1986;Ashmore, 1994;Fenn & Gurnell, 1987;Goff & Warburton, 1994) and research results show that local factors influence its spatial distribution (Ashworth & Ferguson, 1986;Beylich & Laute, 2015;Kociuba & Janicki, 2018;Lane et al, 2017;Orwin et al, 2010;Palmer et al, 2014). These factors were analysed and examined in terms of a number of aspects, including: stream power, channel morphology (depth and width), sediment supply, wall drag, friction angles, grain emergence, turbulent fluctuations, flow aeration, changes in flow velocity, hydraulic gradient and floodplain lithology (Blair, 1987;Carrivick & Heckmann, 2017;Finnegan et al, 2005;Kociuba, 2017aKociuba, , 2017bKociuba et al, 2019;Lamb et al, 2008;Marren, 2005;Midgley et al, 2012;Morin et al, 2018;Parker, Paola, Whipple, Mohrig, Toro-Escobar, et al, 1998;Rainato et al, 2017;Stock et al, 2007;Weckwerth, 2011;Weckwerth, 2018;.…”

“…Knowledge of thresholds in variables controlling relations between local conditions (braidplain lithology and morphometry) and channel lateral erosion rate may help to standardize research results regarding fluvial processes. This can also be helpful in refining locations for measuring the intensity of streambank erosion, especially in terms of long-term changes in braidplain width (Kociuba & Janicki, 2018;Palmer et al, 2014). Additionally, in proglacial setting the role of groundwater seeping and permafrost spatial distribution and dynamics of its active layer can also be considered (Carrivick & Heckmann, 2017;Costard et al, 2003;Kasprzak et al, 2017;Midgley et al, 2013;Outhet, 1974;Strzelecki et al, 2018;Walker et al, 1987;Walker & Arnborg, 1966;Weckwerth & Pisarska-Jamroży, 2015;Weckwerth et al, 2017 because its degradation due to fluvial and thermal erosion affects the transformation of landforms in glacierized catchments.…”