Jökull - 01.01.2009, Side 19

Reviewed research article
Chemical and mechanical fluvial denudation in cold
environments: Comparison of denudation rates from three
catchments in sub-Arctic Eastern Iceland, sub-Arctic Finnish
Lapland and Arctic Swedish Lapland
Achim A. Beylich
Geological Survey of Norway (NGU), Quaternary Geology and Climate group, NO-7491 Trondheim; and
Norwegian University of Science and Technology (NTNU), Department of Geography, NO-7491 Trondheim, Norway
achim.beylich@NGU.NO
Abstract — Chemical and mechanical fluvial denudation rates are analysed in the Hrafndalur catchment in
sub-Arctic Eastern Iceland, the Kidisjoki catchment in the sub-Arctic Kevo region (Baltic Shield area) in north-
ernmost Finnish Lapland and the Latnjavagge catchment in the sub-Arctic Abisko Mountain area in northern-
most Swedish Lapland. In the steep and alpine Hrafndalur catchment denudation rates are relatively high,
with mechanical denudation dominating over chemical denudation due to high mechanical weathering rates
of the rhyolites in this area. Both the Kidisjoki and the Latnjavagge catchments are characterised by low
contemporary denudation rates where chemical denudation dominates over mechanical fluvial denudation. In
Latnjavagge, the low intensity of mechanical fluvial denudation is mainly due to a closed and stable vegeta-
tion cover. The low-relief area of Kidisjoki is characterised by very low mechanical fluvial denudation rates.
Seasonal snowmelt-generated runoff peaks control annual fluvial sediment transport and denudation rates in
Latnjavagge and Kidisjoki whereas rainfall-generated peak runoff is more important in Hrafndalur. In all
three catchments about 80–90% of the annual suspended sediment transport and connected denudation occur
within a few days during peak runoff. These results also confirm that chemical denudation is a comparatively
important process in cold environments.
INTRODUCTION
There is still limited data available on fluvial solute
and sedimentary fluxes and budgets in present-day
cold environments (e. g. Clark, 1988; Barsch et al.,
1994; Gislason et al., 1996; 2006; Dessert et al.,
2006; 2009; Louvat et al., 2008; Eiriksdottir et al.,
2008; Beylich, 2008; Beylich and Kneisel, 2009) and
significant lack of studies comparing both chemical
and mechanical fluvial denudation (e. g. Beylich et
al., 2005b; Beylich and Kneisel, 2009; Eiriksdottir et
al., 2008). More quantitative studies on contempo-
rary fluvial solute and sedimentary fluxes as well as
on fluvial sediment budgets are needed to investigate
relationships between chemical and mechanical flu-
vial denudation in cold environments (Beylich et al.,
2008).
Early work by e. g. Von Lozinski (1909; 1912)
and Peltier (1950) postulated a minor role of chem-
ical denudation in cold environments. In contrast to
this early opinion, Rapp (1960) concluded after his
detailed quantitative studies in Kärkevagge (northern
Swedish Lapland) that chemical denudation was the
most important denudative process in this sub Arctic-
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