ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

the most direct connection betweenTransylvania and Bucharest.
Forest landscape transformed in a short period
turning into a complex industrial and urban landscape
with concentrated towns alongside the valley inside small
depression basins, covering a great part of the glacis-terraced
slopes and of the high riverbed. This landscape is also
dynamic today.
On the opposite, the Bran - Rucar Corridor preserve a typical
rural landscape, with scattered villages on the karstic
plateaus and lenghthened settlements alongside the main
road (an old road that became not very important after the
Prahova Valley opening). Here, man-relief relation is specific
by the permanent settlement access in the altitude,
but also by the increased human pressure by temporary
inhabited settlement (meadow houses).
Different regional planning problems are characteristic for
these two types of landscapes.
ANDREJ MIHEVC
Dolinas, their morphology and origin, the case
of dolinas from Kras, Slovenia
Institur za raziskovanje krasa Zrc Sazu
Titov trg 2 - 6230 Postojna, Slovenia
Dolinas, defined as a closed centric depressions, between
Skocjanske jame caves and Divaca on SE part of Kras plateau
are described.
The surface of this karst area is levelled between 450 in
400 m, but on small scale broken with numerous dolinas,
which are elementary and characteristic morphological element
of the surface. Vadose zone of the karst is thick, as
the free surface of the main underground river is about
250 m under the surface.
On the surface of about 30 km 2 on the map in scale 1:5000
closed depressions, dolinas were analysed. They vary from
10 til - 300 m in diameter and depths from few to over 100
ill. Density of dolinas is up to 240 per km', but the densities
vary depending on different factors.
Morphologically and genetically we can distinguish at least
four types of dolinas in the study area, such as collapsed
dolinas, solution dolinas which develop from underground
karst features and dolinas developed along distinctive tectonic
zones
MARIA MIKHAILOVA
Morphodynamics of river mouth bars
Water Problems Institute, Russian Academy of Sciences
Novaya Basmannaya, 10, p.o. box 231, 107078 Moscou, Russia
A river mouth bar is a complex accumulative object, which
develops at a river mouth as a result of the river and partially
sea sediment deposition under the river-sea interaction.
The main causes of the river mouth bar formation are
the decrease of the velocity of the river flow at the nearshore
and the abstraction of the river flow from the bottom.
The river mouth bars are typical practically for all river
mouths. The river mouth bars are shallow and dynamic
barriers between the river and the sea. So they present significant
obstacles to navigation and require artificial deepening.
Morphology and morphometry of the river mouth bars
depend on water flow and sediment yield of the river or
the delta channel, wave energy, depth and slope of the
nearshore, tides, storm surges, ice regime, artificial measures,
etc.
The development of the river mouth bar under relatively
steady condition usually includes the following stages: 1)
pioneer mouth bar formation; 2) lunate bar formation; 3)
mouth bar widening; 4) central shallow bank formation
and flow bifurcation; 5) scour of the central shallow bank
and flow strengthening. Further these stages are repeated
and a new bar forms seaward. An initial two-channel delta
can be formed after bifurcation if the central shallow bank
is very large or it is consolidated by pioneer vegetation.
Under the natural conditions the stages of the river mouth
bar formation are subjected to the long-term and seasonal
fluctuations of river water flow, sediment yield and wave
energy. During the period with a high water flow the bar
actively protrudes into the sea, its area and height increase.
Over the period with a low water flow the bar is subjected
to wave action and erosion. The spits are the products of
the wave destruction of the bar. The sediments of the longshore
drift can take part in the formation of these spits.
The paper deals with the quantitative analysis of the results
of the field investigations of the river mouth bar morphology,
morphometry and morphodynamics in nontidal deltas
of the Sulak and Terek Rivers (the Caspian Sea) and
the Danube River (the Black Sea). Besides these investigations
carried by the author, data on the river mouth bars in
the deltas of the Yana and Indigirka (Russia, Siberia), the
Daugava (Latvia), the Vistula (Poland), the Huanghe (China)
and the Mississippi (USA) Rivers are also used.
DAVID MILAN
Fine sediment interaction with the pool-riffle system
Department of Geography, DayshBuilding, University
of Newcastle upon Tyne, NE1 7RU, U.K.
Current thinking considering transport of fine-grained
bedload sediments «2 mrn) through pool-riffle systems
that experience velocity reversal, suggest that deposition
initially occurs upon riffles during a spate. During waning
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