ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

termediate complexes of rocks, The development of the
sialic complex began in Archeozoic - Early Proterozoic
and finished in Cenozoic, The development of the mafic
complex is connected with the destructive reconstruction
of the sialic crust of Asia in Paleogene-Neogene. The Moho
discontinuity relief is characterized by difference of depth
reaching 18000 m and corresponds to its ( Moho discontinuity)
dome-shaped rise in the place of the Central Basin,
CARLA SEMIRAMIS SILVEIRA & ANAL, COELHO NETTO
Hydrogeochemical basin responses to rainfall inputs in a
tropical mountainous rainforest environment:
Rio de Janeiro, Brazil
Ceoheco, Laboratory of Geo-Hidroecology, Departmento de
Geografia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
The spatial and temporal pathways of water reflect the interactions
between climate, biota, soil, relief and weathering
processes under distinct bedrock. Detailed studies on
the-solute fluxes of hydrological processes aim to provide
basic informations of the evolution of weathering. The
study area is a small catchment (3.5km 2 ) located in the
southern slopes of Tijuca massif, Rio de Janeiro. The secondary
rainforest (Tijuca Forest National Reserve) is still
preserved despite a strong urban pressure in the surrounding.
Previous work at this basin provides knowledge of
the internal operation of hydrological processes. Block
escarpments are seen as important recharge zone to feed
subsurface flow due to percolation in the joint system, besides
overland flow. The soils were derived from colluvial
deposits and precambrian bedrock (biotite gneiss, plagioclase-microcline
gneiss and microcline .granitoid) showing
low cation exchange capacity.
Precipitation and discharge measurements were conducted
at the basin outlet. Rainfall, throughfall and water below
the litter cover were collected to evaluate the chemical input.
Six points were selected to monitor streamwater based
on hydrological behavior and lithological differences.
Water was analyzed for Ca 2 +, Mg 2+ (atomic absorption
spectrophotometry); Na', K+ (flame emission spectroscopy)
and cr, Si0 2 (colorimetry). Water samples were
taken weekly for eight months and continuously during seven
rainfall events to analyze the relationship between
stormilow discharge and solute fluxes.
The results show that chemical input by rain water is lower
than strearnwater output for all elements. Throughfall's
composition is higher for all elements and pH, demonstrating
the effect of neutralization exerted by vegetation. Litterflows
incorporate Ca 2 + and K+ but were considered negligible
to stormtlow. Output at the stream was characterized
by an increase in all elements (except forK+) in relation
to throughfall demonstrating that it is an important
nutrient uptake by vegetation.
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Spatial variations show a good correlation between lithology
and streamwater chemistry. Biotite gneiss proved to
be a source area of Mg 2+ to streamwater, while microcline
granitoid was responsible for higher concentrations of K+.
The basin showed a quick hydrological and geochemical
response to rainfall inputs. Different contributing areas result
in a chemical lagtime between monitored points and
the outlet of the basin. The concentration of all elements
decreases during the rising limb of the hydrograph, This
dilution is attributed to overland flow. The subsurface
stormflow was characterized by high concentrations of all
elements. However when groundwater seems to prevail the
composition is marked mainly by Si0 2 and Na",
BRAS RAs K. SINHA
Interference of human resources in geomorphic systems
Department of Geography, Visva-Bharati University,
Santiniketan-731235 West Bengal, India
Human resources and geomorphic phenomena are the two
important aspects of geography and the roots of these two
date back to the postulates like physical vs. human or determinism
vs, possibilism in geography. Human resources
and geomorphic processes and features of geomorphic systems
are the components of human and physical geography
respectively. Both are interwoven and the effects of
these two are seen on one another.
Human resources are the sum total of knowledge, skills,
talents, strength, energies and other qualities actually or
potentially available in all people of a region which they
exercise or may exercise in performing their activities. Human
resources both in quantitative and qualitative terms
are considered as an active anthropogenic agent. Human
beings applying their vigour and technological devices
with the aid, advice and consent of the nature alter and
modify the shape, size, nature and forms of several types
of geomorphic landforms/ features and interfere the
landforms processes of alluvial, aeolian, glacial, coastal and
karst systems for preparing cultural means to satisfy the
needs of the people in the society.
However, while doing so human resources sometimes became
inactive in its action after some certain limits of geomorphic
constraints and create some geomorphic hazards
which affect adversely the human society.
In this way human resources by interfering the natural state
of geomorphic systems create both the positive and negative
impacts at large scale on the earth's surface.
Since the above theme has not received much attention of
the scientists including geographers, the present paper focuses
attention on the types of human resources and their
activities such as agricultural, mining and quarrying, industrial,
construction, commercial, transport and communication
etc. and their possible interference in the geomorphic
systems and impacts on the geomorphic processes