Effects of high‐magnitude/low‐frequency fluvial events generated by intense snowmelt or heavy rainfall in arctic periglacial environments in northern swedish lapland and northern siberia

Abstract

In the Latnjavagge drainage basin (68°21′N, 18°29′E), an arctic‐oceanic periglacial environment in northernmost Swedish Lapland, the fluvial sediment transport and the characteristics and importance of high‐magnitude/low‐frequency fluvial events generated by intense snowmelt or heavy rainfall have been investigated and compared with snowmelt‐ and rainfall‐induced discharge peaks in the Levinson‐Lessing Lake basin (Krasnaya river system) on the Taimyr Peninsula, an arctic periglacial environment in northern Siberia (74°32′N, 98°35′E). In Latnjavagge (9 km2) the intensity of fluvial sediment transport is very low. Most of the total annual sediment load is transported in a few days during snowmelt generated runoff peaks. Due to the continuous and very stable vegetation covering most areas below 1300 m a.s.l. in the Latnjavagge catchment, larger rainfall events are of limited importance for sediment transport in this environment. Compared to that, in the c. 40 times larger Krasnaya riversystem rainfall‐generated runoff peaks cause significant sediment transport. The main sediment sources in the Latnjavagge drainage basin are permanent ice patches, channel debris pavements mobilized during peak discharges and exposing fines, and material mobilized by slush‐flows. In the Krasnaya river system river bank erosion is the main sediment source. In both periglacial environments more than 90% of the annual sediment yield is transported during runoff peaks. The results from both arctic periglacial environments underline the high importance of high‐magnitude/low‐frequency fluvial events for the total fluvial sediment budgets of periglacial fluvial systems. Restricted sediment availability is in both arctic environments the major controlling factor for this behaviour.

Downstream patterns of suspended sediment transport in a High Arctic river influenced by permafrost disturbance and recent climate change

“…Hence, this research indicates that sediment storage remains an important process five years after catchment disturbance. These results are broadly consistent with studies in other regions where catchment perturbations that cause increased sediment availability are buffered through channel storage processes (e.g., Beylich and Gintz, 2004;Beylich and Sandberg, 2005). In combination with a reduced period of sediment transport during snowmelt high flow conditions caused by channel snow pack, the Arctic fluvial system appears to be effective at dampening the downstream fluvial impact of catchment disturbance in a manner consistent with other settings.…”

Environmental Monitoring and Research in the Abisko Area—An Overview

“…Most of it has been eroded along and close to the riverbanks. It can be concluded that it is mainly the rapid mass-wasting processes that transport sediments along all of the cascading systems (Jonasson and Nyberg 1999;Jonasson et al 2002;Beylich and Gintz 2004).…”

“…Ongoing hydrological monitoring has shown the importance of high magnitude/low frequency discharge events (Gude et al 2000;Beylich and Gintz 2004), in particular during summer and autumn rainstorms. At two occasions during the last decades, some of the rivers affected by rainstorms have carried suspended sediments in 1 or 2 h that normally require several years to be transported (Jonasson and Nyberg 1999).…”

Mass Transfers and Sedimentary Budgets in Geomorphologic Drainage Basin Studies

“…Translation slides 11. Deflation With respect to the temporal variability of process intensities and/or process frequencies the main snow melt period (late May -June/July) which is characterised by high runoff, increased fluvial transport, slush flow activity, ground avalanches and rock and boulder falls as well as August which is the month showing the highest frequency of extreme rainfall events (Beylich, 2003;Beylich & Gintz, 2004) triggering debris flows, translation slides, secondary rock falls, boulder falls, peak runoff and increased fluvial transport, can be pointed out as periods with comparably high activity. The period from late October until early May is compared to that characterised by only very little (single avalanches) or no activity (Beylich et al, 2006b;Beylich, 2008 (Beylich & Sandberg, 2005).…”

“…Stable freezing temperatures with little daily fluctuation at 10 cm above ground and autumn snow accumulation usually occur from September/October onwards. Regarding the summer months June -August, August shows the highest mean precipitation (82 mm) and also the highest frequency of extreme rainfall events (Beylich, 2003;Beylich & Gintz, 2004). Precipitation from June to August accounts for about one quarter of the mean annual precipitation.…”