ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

erosion might be active due to the ecological parameters
(ecologically critical areas Eca). Taking the Landsat and
SPOT images the soil wetness index (Swi) were calculated.
On the Swi relates to canopy and soil moisture. We supposed
that the driest areas (Swi < 6 %) exposed to wind erosion
a greater extent. Overlapping the maps of physical parametes
by the SWI map and the landuse map good correlations
were found between the landuse and Swi indexes.
Grey - SWI < 6 % , black - alkali soils , encircled - depressions between
sand dunes?
KATERINA MICHAELIDES & JOHN WAINWRIGHT
Slope-channel coupling: effects on slope evolution and
channel response
Department of Geography, King's College London, Strand,
London WC2R2LS, U.K.
There is a strong interaction between catchment form and
its flood and erosion response. Over geological timescales,
the catchment form is influenced by the flood and erosion
response, and vice versa. Slope-channel coupling is an important
factor in this interaction. First, it gives the boundary
conditions for the base of the slope, and hence its
evolution through time. Secondly, it determines the
amount and timing of sediment and water inputs into the
channel system. Previous studies have demonstrated that
the presence of floodplains separating hillslopes from
channels strongly affect discharge downstream and alters
the amounts of sediments entering the channel. Floodplains
act as a storage or buffer zone for water and sediments
coming off the hillslope and also from overbank
flows. For these reasons, an in-depth understanding of slope-channel
coupling is fundamental to our understanding
of both the short-term response of catchments, and their
long-term evolution.
Several Mediterranean catchments have been investigated
in terms of their coupling characteristics. A number of differences
have been noted between these channels. First,
the angle of dip of the floodplain is not always horizontal
as most studies have assumed. Certain floodplains dip
towards the channel, with varying angles, whilst others dip
away from the channel and towards the hillslope. These
patterns appear to be related to differing channel flow regimes
and land uses. Secondly, roughness of the floodplains
varies both downstream and across the channel.
Thirdly, vegetation characteristics vary in response to the
coupling characteristics. Vegetation on floodplains is more
developed than the more frequently disturbed main channel
vegetation, and enhances the buffering capability of the
floodplain. Fourthly, sediment size varies in relation to the
coupling characteristics, and this has further feedbacks to
the floodplain roughness and infiltration. Fifthly, the distribution
of floodplains follows the oscillations of the
channel plan, but is also controlled by the location of tributaries.
A simple model has been developed to investigate the interactions
between slope evolution and catchment response
for a variety of scenarios of coupling. The results from this
investigation further illustrate the importance of the interaction.
More detailed studies of this relationship in the
field are already underway.
YVES MICHELINI, THOMAS CURT 2 , ETIENNE JOSIEN1,
CHRISTOPHE POIX 3 & CHRISTIAN COUGOUL 4
Utilisation de nouvelles techniques de localisation
et de traitement des donnees geographiques appliquee a
l'etude de la pedogenese en milieu volcanique complexe:
I'exemple de l'estive experimentale de Ternant
(Massif Central francais)
1 Enita, Cnrs Ura 1562,63370 Lempdes, France
2 Cemagref, Cnrs Ura 1562, Laluas 63100 Riom, France
3 Departement Sciences de l'ingenieur, Enita, 63370 Lempdes, France
4 Departement Agricultures et espace, Enita, 63370 Lempdes, France
A proximite immediate des edifices volcaniques de la chaine
des Puys (Massif central francais), Ie plateau granitique
ou gneissique s'est trouve plus ou moins recouvert de saupoudrages
varies dans leur composition (trachytique, trachyandesitique,
basaltique) et dans leur taille (cendres fines
de taille millimetrique a centimetrique) durant tout Ie
tardiglaciaire et Ie debut de l'holocene. La dynamique des
versants et la pedogenese ont ainsi ete profondement perturbees
et lactivite humaine (deforestation, mise en culture,
parurage) puissante et continue depuis 1'age du bronze
a encore amplifie ce phenomene,
Sur Ie site experimental de Ternant (60 ha, 10 km al'ouest
de Clermont-Ferrand, 1000 m alt.), une carte des sols au
1/4500 erne a ete realisee par quadrillage systematique
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