Jökull - 01.07.2003, Blaðsíða 35

Reviewed research article
Present morphoclimates and morphodynamics of Latnjavagge,
the northern Swedish Lapland and Austdalur, east Iceland
Achim A. Beylich
Department of Earth Sciences, Geocentrum, Uppsala University, Uppsala, Sweden; Email: Achim.Beylich@geo.uu.se
Abstract – Until recently, the present-day climate has often only been characterized by monthly and annual
means or sum values of wind speed, temperature, and precipitation. As most geomorphologic processes con-
sist of discrete events which are only partly correlated to these meteorological means or sum values, there
is a need for an additional approach of statistical analysis of meteorological data. In this investigation the
“morphoclimates” of Austdalur, in Seyðisfjörður, East Iceland and Latnjavagge, in the northernmost Swedish
Lapland are analysed with particular emphasis on (1) the frequencies or recurrence intervals of meteorological
events of given magnitudes, and (2) the frequencies of geomorphologically important thresholds. Aspects of
the wind, temperature, and precipitation regimes which control the type, frequency, duration, intensity and the
sediment budgets in the two periglacial environments are presented. In Austdalur aquatic slope denudation
is more important than chemical denudation. The Latnjavagge drainage basin is characterized by a domi-
nance of chemical denudation over mechanical fluvial denudation. In both environments the intensities of the
geomorphologic processes operating in the present periglacial morphoclimates are low.
INTRODUCTION
It is expected that predicted climate change will cause
major changes in polar and subpolar environments.
From a geomorphological point of view, it is of in-
creasing importance to obtain a better understanding
of the relationships between present-day geomorpho-
logical processes and present-day climatic conditions
to get a more reliable assessment of the possible geo-
morphological effects of climate change.
According to Chorley (1962), and Chorley and
Kennedy (1971), drainage basins are open geomor-
phologic systems, which are parts of higher and larger
systems and are connected to these by transfers of
energy and material. Fluvialmorphologic process-
response systems - consisting of static components
(material components, form components), process
components and the relationships between static com-
ponents and process components - are driven by en-
dogenic and exogenic energy supplies like crustal
movements and meteorological events (Chorley and
Kennedy 1971; Ahnert 1998). In process geomor-
phological investigations the exogenic energy sup-
plies are often only characterized by annual and/or
monthly sums or mean values of precipitation, tem-
perature, and wind speed (see e.g., Peltier 1950;
Fournier 1960; Chorley et al. 1984). As, however,
most geomorphologic processes consist of discontin-
uous process events, not or only partly correlated to
these meteorological sum or mean values, there is a
need for an additional approach of statistical analysis
of meteorological data.
Ahnert (1982; 1986; 1987; 1988; 1998) developed
a “morphoclimatology” specially related to geomor-
phologic needs. “Morphoclimate” in this sense is de-
fined as the totality of those climatic characteristics
of an area that influence the type, frequency, duration
and intensity of the exogenic geomorphologic pro-
cesses in this area. The statistical method primarily
used in this context is the magnitude-frequency anal-
ysis; it provides evidence of frequencies and recur-
JÖKULL No. 52, 2003 33