ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

EDI CHIARINI 1, MAURIZIO DEL MONTE 2,
MAURIZIO D'OREFICE 1, PAOLA FREDI 2 ,
ELVIDIO LUPIA PALMIERI 2, FRANCESCO PUGLIESE 2
& RENATO VENTURA 1
Geographic Infomation Systems
for morphometric characterization of drainage basins
1 Servizio Geologico Nazionale, via Curtatone 3, 00100 Roma, Italy
2 Dipartimento di Scienze della Terra, Universita La Sapienza,
p.le AIda Mora 5,00185 Roma, Italy
Quantitative definition and representation of natural phenomena
and of their morphological effects is a growing
need both in geomorphological researches and in the applications
of geomorphogical knowledge to the problems of
proper land management. This paper is framed into this
context and its aim is to estabilish a methodology to analyze
and classify the studied territory on morphometric basis.
It is well known that drainage basins are the basic geomorphic
units and many studies from all over the world
showed that most of their orographic and hydrographic
characteristics can be expressed, synthetically and properly,
throught appropriate geomorphic parametres; for
this reason, the sample area of this study is a drainage basin.
More precisely the drainage basin of Fiume Salto has
been chosen; it is located in Central Italy and shows wide
heterogeneity in the geological and morphological conditions
within an area of suitable size.
The most significant geomorphic parametres have been
calculated for the sample drainage basin; the interdependence
among the chosen parametres and their spatial variability
as function of lithological and tectonic conditions
have then been investigated in order to produce cartographic
synthetic representations.
The enquiry has been carried on applying computer assisted
procedures according to Arc/Info system and new
special programmes elaborated by the authors.
Orographic digital data by Igmi available at the scale
1:25 ,000, have been appropriately controlled and integrated
by introducing new spot elevation. Hydrographic data
have been drawn from Igmi topographic maps at the scale
1:25,000 and integrated through aero-photographic and
field observations; successively they have been transferred
on paper stand and acquired as numerical values by scanner.
The digital hydrographic network has finally been verified
by checking stream junctions.
Data processing procedures can be summarized into the
following three groups:
-- elaboration of a digital elevation model which considers
divides, thalwegs and closed depressions; elaboration of
slope and aspect maps, relief amplitude maps, shaded relief
maps;
- automatic hierarchization of drainage networks, calculation
of morphological parametres of single drainage basins
by means of programmes assembled by the same authors;
construction of maps of hierarchizated drainage networks
and of drainage density;
- identification of stream preferential orientations through
automatic analysis of stream rectilinear segment azimuthal
distribution (this analysis, executed by cumulative length,
has been applied to the whole drainage network and to the
different stream order within each outcropping lithologies);
identification of fault and slope preferential directions
by means of programs suitably run by the authors.
The basic result obtained following the above methodology
is the construction of a data base for the study area,
which allows the surveyed data to be speedly elaborated,
compared and mapped. Moreover the integrated analysis
of the different information levels can led to the automatic
production of diagrams and map. Some examples of both
the possible representations have then been produced.
The first example is a set of graphic elaborations which
show the prevailing orientations of slopes and the preferential
orientations (domains) of stream directions, as a
function of stream order and outcropping lithologies; the
integrated analysis of the two kinds of graphs can allow the
identification of stream orientations which, being not congruent
with slopes, are likely to be structurally controlled.
The second example is one of the possible thematic map
obtainable. The map chosen as sample shows the areal variations
of denudation process entity evaluated as function
of drainage density and slope, taking into account also the
different outcropping lithologies.
YURIY CHIZYKOV
Dusty storms as a factor of modern relief-formation
(by example of Belarus)
Institute of Geological Sciences, Academy of Sciences of Belarus,
Zodinskaya str. 7, 220141 Minsk, Belarus
The territory of the Republic of Belarus is in the humid zone.
The moderate climate conditions cause a favourable
geomorphological surrounding. Nevertheless the climate
conditions in some years may change in rather considerable
ranges. For all that the extreme climate parameters
(strong winds, low air humidity, sharp daily temperature
overfall, low amount of precipitations, genetic features of
the earth surface (a wide spreading of the loess-like rocks)
promote the creation of the favourable conditions for the
manifestation of the catastrophic nature phenomenon-dusty
storms. Dusty storms envelop considerable areas and
draw into air stream a bulk of soil by moving it both on the
surface and on the different height. They assumed the most
destructive character on the territory of the Belarus Polesje
(the south part of the Republic). By the data of Belgidromet,
it is fixed more than 40 cases of dusty storms during
the last 30 years in the region of Gomel (the maximum
amount for Belarus), near Lelchitsy-about 40, near
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