ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

vertines are cyanobacteria. The precise role of microbes in
travertine deposition is still in dispute, especially in meteogene
environments. However, travertine fabric and microstructure
are unquestionably related to microbial activity.
In the tropical environment of Louie Creek, variations in
microbially-controlled fabrics appear to be related to local
hydrodynamic changes rather than climatically-induced
constraints on microbial communities, which is largely the
case with meteogene travertines from temperate regions.
Travertines showing alternating microbial and larvae fabrics
are similarly the result of hydrodynamic changes. Such
hydrodynamic control has implications for palaeoenvironmental
interpretations of fossil travertines.
D. DUCCI ', ANTONIO GALL0 2 , GIUSEPPE ONORATI 3
& LORENZO TORALD0 2
Fluvial changes in the Calore River watershed during the
last century (Southern Italy)
lIstituto di Geologia Applicata, Universita di Napoli Federico II,
p.le Tecchio 80,80125 Napoli
2 Dipartimento di Scienze della Terra, Universita di Napoli Federico II,
largo S. Marcellino 10,80138 Napoli
3 Servizio Idrografico e Mareografico Nazionale,
via Curtatone 3, 00187 Roma
The Calore River is a left hand tributary of the Sele River
which flows into the Salerno Gulf (Thyrrenian Sea ­
Southern Italy), The main water course stretches 82 km,
with an average profile slope of 1,4 0/0, draining a watershed
of about 680 km 2 with an average altitude a.s.l. of 650
m, The Calore River watershed has been chosen for the
evaluation of recent fluvial changes because of the scarcity
of river control manufacts until today: since 1994 it belongs
to the Cilento «National Park». Moreover this watershed
shows most of the peculiar features of the Southern
Italy landscape: - the mountain relief, forming the major
drainage divide, consists of carbonate massifs (Mts. Alburni
- 1742 m , Mt. Cervati - 1899 m, Mt. Motola - 1745 m,
Mts. Soprano-Chiaianello - 1318 m) with a coarse drainage
network (1-2 km/krn") and several endoreic areas of karst
origin; - the hilly central part of the watershed is characterised
by flysch terrain where both landslides and fluvio-denudation
take place and originate a medium density drainage
network, strongly influenced by local lithological variations;
- the terraced alluvial plain constitutes a small
portion of the watershed and is partitioned in 3 major terraces,
an older dissected Pleistocene coarse debris (Persano
group Auct.) terrace, and two Olocene terraces, which
are crosscut by the last 30 km of the meandering Calore
River.
In order to evaluate the influence of the climate, and hence
the hydrologic regime, on fluvial geomorphologic changes,
data since 1920 concerning temperature, precipitation, flu-
vial and spring discharge, as well as man made water catchments,
have been used to calculate the time variations of
the water balance and the recurrence time of major floods.
The fluctuations of the water balance have been analysed
on the basis of the most widespread evapotranspiration
formulas, used in literature, looking at the monthly data
and applying a Gis regionalization of point data. As far as
the springs regime is concerned, both direct measurements
and estimates based on summer fluvial discharges have
been analysed, showing the increase in underground water
exploitation during the last decades. The floods have been
studied on the basis of both large events, followed in the
field, and historical hydrological record, looking at the hydrometric
levels associated to the bankfull stages and overbank
discharges, furthermore an estimation of the long
term variations of peak discharges has been attempted
starting from the yearly maxims.
The erosion regime has been evaluated, according to a
quantitative geomorphology approach, by digitising the
whole drainage network and calculating drainage density
and Strahler's ordering parameters. The estimated total
yearly solid discharge for each III order drainage subbasin
has been hence attributed to its confluence with the main
river talweg. So the effect of these confluences upon the
Calore River path has been studied and the possible relations
between sediment yeld fluctuations, associated with
climate and landuse, and the evolutionary trend of the
main water course have been evaluated.
The analysis of the fluvial bed variations in the alluvial
plain has been carried out by: geomorphologic mapping at
1: 10,000 scale, multitemporal comparison of topographic
maps drawn from 1745 to 1994, overlapping of about hundred
cross-sections of the river bed at gauging sites. On
the whole the river bed shows neither vertical erosion nor
deposition. As demonstrated by the study of the fluvial
sections and by the geomorphologic mapping, only 1 m
scour and fill yearly fluctuations, related with floods and
summer low levels, have been observed. The river path, instead,
varied from anastomozing to meandering, with a
width decrease reaching 50 % and a sinuosity increase to
about 1.6, associated with a lengthening of the water course
of about 9 km in a century.
At present, in these geomorphic processes a key factor
seems to be the agricultural exploitation of the alluvial
plain, with the machinery flattening and compacting of the
river bank zones and the abandoning of the bankfull stage
slopes. This kind of landuse strengthens the natural tendency
of the river toward meandrification because the
abandoned zones are covered by a composite vegetation
(also with large trees), which protects the slopes from erosion
during floods. In fact, looking at large floods in the
field (December 1993, November 1996), in the flooded
Holocene terraces, with a depth of water over 2 m, marked
discharge and erosion processes were confined to a few sites'
showing a peculiar water flux regime, mostly due to
obstacles (i.e. trees, guard-rails, etc.).
In conclusion the recent evolution of the Calore River can
be depicted as a slow fluctuating tendency toward meandrification,
in relation to the present day climate and lan-
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