ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

termined from the area-rank relationship and varied from
1.86 ± 0.01 on June 30, to 1.90 ± 0.00 on July 4, to 1.74 ±
0.00 on July 7. The decrease in D, between July 4 and July
7 would indicate a greater concentration of the particle
area over a small number of large particles. Although the
decrease in D k is consistent with observed changes in the
particle size distributions, D k should be used with considerable
caution because D k varied more than one standard
error between replicates. Dr and D 2 were determined from
the length-perimeter and length-area relationships, respectively.
Dr proved to be of little value for quantifying changes
in particle morphology as it showed little change through
time despite considerable visual changes. D 2 , however,
was useful, despite some variation between replicates.
Over the sampling period, D 2 for the composite data sets
showed a steady decrease from 1.74 ± 0.02 on June 30, to
1.68 ± 0.02 on July 4, to 1.60 ± 0.01 on July 7. This change
in D 2 indicates that through time the larger particles became
longer and thinner relative to the smaller ones.
This study shows that temporal changes in D, Db and D 2
were consistent with, and allow quantification of, observed
changes in particle morphology. Dr did not reflect observed
morphological. changes, and is likely of little value for
this type of study. The changes in particle morphology
coincided with an increase in primary production in the
form of algae.
FERNANDO O. DE FRANCESCO 1, ENRIQUEJ. SCHNACK 1 ,2,
JUAN A. SCHNACK 1,3, LUIS C. GARCIA LOZANO 4
& UBALDO R. COLADO 1,2
The floodplains of Northeastern Argentina.
Geomorphic components and environmental impacts
of flood control projects
1 Facultad de Ciencias Naturales y Museo, Universidad Nacional de La
Plata, Paseo del Bosque, 1900 La Plata, Argentina
2 Comisi6n de Investigaciones Cientificas de la Provincia
de Buenos Aires, La Plata, Argentina
3 Consejo Nacional de Investigaciones Cientfficas y Tecnicas,
Buenos Aires, Argentina
4 Fundaci6n Neotr6picos, Calle 50 N/3850,
Of. 204, Medellin, Colombia
The lower Paraguay and the middle to lower Parana are typical
alluvial rivers characterised by extensive floodplains
and very low topographic gradients, where channel migration
and island development are common features. These
characteristics, together with periods of heavy rainfall
within their entire watershed (ca. 3 million km) cause the
recurrence of inundations affecting population and natural
systems. The latter are naturally adjusted to this pulsatile
regime, but the human occupation of the area causes modifications
in natural habitats. Although at the beginning
of European occupation in the region (i.e. the Jesuits, since
the sixteenth century), the early settlers applied some
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«common sense» geomorphic criteria by establishing their
communities as high as possible, far from the reach of
floods, the most recent developments within the present
century have not had proper planning criteria. The main
urban areas are sited on the floodplains and are periodically
exposed to severe damage, both in property and infrastructure.
Some housing projects have been developed on
inactive meanders. The lack of adequate systems for potable
water and for sewarage disposal, as well as the existence
of untreated industrial wastes poses a serious threat to
human health, particularly when the persistence of a flood
is long (several months in 1983). As a consequence of the
various flood events, defence works (terreplains, pumping
stations, channelisations) were performed during recent
emergencies and others are being planned around the
main cities within the region. Because all of the planned
structures will only have local effects, it is foreseen that minimal
impacts will be suffered at a regional scale. However,
it must be considered that the creation of artificial
landforms (straightened streams, ponds, terreplains). may
cause impacts in local systems implying alterations in the
flow pattern, destabilization of river islands and stagnation
of water around urban centers. The latter will favour the
establishment of disease vector fauna. In addition, it must
be taken into account that wetlands and gallery forests are
typical in the area and host a very rich biodiversity. With
the purpose of assessing the impacts of 51 flood control
projects, a standard procedure was developed and applied
in each case, involving impact identification, vulnerability
of the proposed project, and mitigation measures.
SANDRO DE MURO, MICHELE CAMIN
& GIOVANNI PAOLO FANZUTTI
Geomorphological map of the coastal and marine area
between Punta Sardegna and Culuccia Peninsula.
New deglacial sea level records from underwater surveys
and dating intergranular cement of beachrock.
(North-eastern Sardinia, Italy)
Dipartimento Scienze Geologiche, Ambientali e Marine,
via E. Weiss 2, Trieste, Italy
Geomorphological, sedimentological and chronological
studies have been carried out in the sector extending
between Punta Sardegna and Culuccia Peninsula in northeastern
Sardinia (Strait of Bonifacio and Arcipelago di La
Maddalena).
The 1:8,000 geomorphological scale map was compiled on
the basis of new data collected during three oceanographic
and on -field survey expeditions (in 1994, 1995, 1996). The
information contained in the map mainly refers to the more
dynamic zone of submarine beaches. The bathymetric
strip located between -30 m and the emerged beach, is
analysed in detail.