ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

niest month of each year (mm); P = annual rainfall (mm);
( H "tg a) == orographic coefficient (rn),
The analysis of monthly rainfall data for Rome time series
indicates that the p 2 /P ratio tends to decrease. In order to
have an idea of the effects of such decrease, the Fournier
formula was applied to the data of Rome (tab. L), with an
orographic coefficient of 16.50, as in the Fournier work.
TABLE 1 - Variations in p2jp and D.S. in the basin of the Tiber River
Station Period
Rome 1882 - 1938
1939 - 1995
p2jp D.S. (t/km/yr) D.S. variation (%)
47.9 2837
42.0 2003 --- 29
Actually in the last few decades in Italy there has been a
considerable decrease in solid transport, with serious damage
to structures (bridges) taking place and erosion at
most beaches (Martinis, 1988). These are attributed in general
to man; s activities (dams, excavating of inert materials
from river beds, etc.). Man's activities are certainly the
major cause of these phenomena; however in light of the
data given in Table 1, perhaps it is necessary to consider
whether the variations found in the p 2 /P ratio might not
contribute in some way to the actual decrease in solid
transport.
DEIRDRE DRAGOVICH 1 & R. MORRIS 2
Runoff and sediment loss following bushfires
in eucalypt forest, Australia
1 Department of Geography, University of Sydney,
Sydney 2006, Australia
2 NSW National Parks & Wildlife Service, p.o. box 1393,
Gosford South, NSW 2205, Australia
Bushfires are an integral part of the Australian environment
and vegetation has largely adapted to this by developing
mechanisms for rapid regeneration. Woodlands and
forests of Eucayptus spp occur within the Sydney metropolitan
region, and in the nearby Blue Mountains. Bushfire
activity was widespread in eastern Australia during 1994
when much of the region was affected by drought. Fires
are common in the Blue Mountains: more than 400 bushfires
have been documented Over a 28-year period. The eucalypt
vegetation, mild climatic conditions and rugged terrain
contribute to a high fire susceptibility.
Increases in soil erosion following fire have been reported
previously in eastern Australia. Rates of sediment loss in
the post-fire landscape are affected by fire intensity. This
study compared runoff and sediment movement on land
which had been subjected to high, moderate and low (unburnt
in the last fire) intensity burns. A total of 12 sediment
plots were sited in upper and lower slope positions
with gradients ranging from 11 to 13 degrees. Plot design
152
followed that of Riley & alii, (1981) and each plot measured
runoff and sediment yield from an area of 8m 2 • A total
of 4 closed and 4 open plots were installed on high and
medium intensity burn sites in upper and lower slope positions.
On the low intensity burn site, 2 open plots were
constructed in each of the upper and lower slope positions.
Monitoring of runoff plots extended over a sixmonth
period during which 11 collections were made.
Rainfall for the first eight months in 1994 was only 423
mm, less than half the long-term average.
Combined cumulative runoff for the 4 plots in upper and
the 4 in lower slope positions was 250.5L and 250.9L respectively.
Runoff from the high intensity burn plots had a
mean value of 11.8L for the 11 collections, the moderate
intensity burn plots 7.1L, and the unburnt plots 2.9L.
Sediment yield included surface wash, bioturbation, and
organic matter. Surface wash averaged 111.5g from plots
on slopes with a high intensity fire; 60.5g for slopes with a
moderate intensity burn; and 6.8g for the unburnt slope.
Large variation occurred between the 12 plots on all collection
days. Total surface wash was 4906g for the high intensity
burn slope, 2660g for the moderate intensity, and
299g for the unburnt slope. The lowest leaf material addition
occurred on the unburnt slope, and the highest on the
slope with a moderate intensity fire. Bioturbation, involving
mainly ants and animal scratchings, was identified in
33 % of the sediment collections. The highest contribution
of bioturbation to total sediment movement occurred on
the moderately burnt slope.
Fire intensity influenced the amount of total downhill sediment
movement, with the greatest amount being collected
from the plots on the moderately burnt slope. However,
no significant difference occurred between total sediment
collected from the high and the moderate intensity burns.
Significantly more sediment was collected on both of the
burnt slopes compared with the unburnt slope. Both runoff
and surface wash were greatest on slopes with high intensity
fires, and lowest on unburnt areas. When bioturbation
and organic matter were included in total downhill
movement, losses were highest on the moderately burnt
slope and least on the unburnt. slope.
FRANCESCO DRAMIS 1, MARCO MATERAZZI 2
& GIUSEPPE CILLA 2
Influence of climatic changes on travertine deposition
during Holocene: a new hypothesis
1Dipartimento di Scienze Geologiche, Universita di Roma Tre,
via Ostiense 169, 00154 Roma, Italy
2 Dipartimento di Scienze della Terra, Universita di Camerino,
via Gentile III da Varano, 62032 Camerino, Italy
Observations made in different parts of the world (Goudie
& alii, 1993; Berakhi & alii, in press; Calderoni & alii, in