ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

stems to external forcing, and in particular to climatic
change. The ecotonal nature of alpine/subalpine systems
suggests a particular sensitivity to climatic change. In contrast'
the sediment system in such basins is characteristically
poorly linked (Caine, 1986) suggesting that impulses of
change may not be efficiently transmitted through the sediment
system. Therefore, a priori the extent to which alpine/subalpine
geomorphic systems will be sensitive to climate
change remains unclear.
This paper describes research on four alpine/subalpine basins
in the Cascade Mountains of southern British Columbia.
The study aims to empirically illustrate the sensitivity
of the basins to external climatic forcing by comparison of
Holocene sediment stratigraphy with the palaeoclimate record.
Lake sediment derived estimates of sediment yield
provide an integrated measure of geomorphic activity
within the basins during the Holocene. Sediment yield to
the basins increased significantly in the second half of the
Holocene. Comparison of the sediment yield changes with
the local and regional palaeoclimate. records indicate that
long term changes in sediment delivery to the lakes are
correlated with the pattern of Holocene climate changes.
Approaches to establishing the process basis of this relation
are discussed.
EZE BASSEY EZE & ADETOYE FANlRAN
Rainsplash detachement on different landuse surfaces
in sub-urban Ibadan, Nigeria
Department of Geography, University of Ibadan, Nigeria
Splash erosion on forested surfaces has been relatively neglected
in geomorphological studies: the assumption seems
to be that splash takes place mainly on bare surfaces. The
neglect is particularly pronounced in the humid tropics.
This study is part of a recently completed Ph.D. work in
the Department of Geography, University of Ibadan (Eze,
1996) aimed at filling the recognized gap. The specific
aims of this study included:
a) measuring and analysing the quantity of splashed soil
on different landuse surfaces-bare, cropped, teak plantation,
grass and natural forest;
b) relating the splash data to the environmental (controlling)
factors of erosivity and erodibility;
c) build models capable of predicting splash on the studied
surfaces in particular and similar surfaces in general.
The modified Morgan's splash cup was used in the field to
collect the splashed soil during the rainfall year (March to
October of 1993), a normal rainfall year in the town. A total
of 50 rainstorm events was studied. The least amount of
rainfall that resulted in splash was 0.9 mm. The intensity of
the rainstorms ranged between 3.6 and 149 m/hr. and the
total energy load 21443.24 jim.
The following are highlights of the result:
a) Splash occurred on all the surfaces studied.
b) Splash detachment was rather high, being far above
the generally recognized figure of 1.3 cg/rn/yr. It ranged
between 49.25 kg/m' on grass to 99.39 kg/rn' on bare
surface.
c) The general progression was of the order: bare > teak
plantation> cropped> forest> grass surface.
d) Application of Duncan's (1955) multiple range test
produced only three distinct surfaces of bare, cropped/
teak plantation and forest/grass surfaces.
e) The models developed show that splash in the area can
be explained largely by clay content, percentage cover,
A115, EI30, rainfall amount, built density and organic
matter content of the soil, in that order.
f) Grass has shown up as the best to use for the protection
of surfaces against splash, as has been shown for soil and
nutrient loss (Daura, 1995) and runoff (Oyegun, 1980), in
the same locality of humid tropical sub-urban geomorphological
environment.
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