1,721,022 research outputs found
Evaluation of erosion in equipped basins. Preliminary results of a comparison between the Gavrilovic model and direct measurements of sediment transport
No full textThe study of the hydrologic characters of a water
course permits the correct management of the corresponding
basin and a greater control over the water resources of the
whole basin; therefore, a suitable planning and maintenance
of the necessary interventions along the water course,
especially in proximity of the outlet to sea, becomes necessary.
An evaluation of the solid transport allows an
estimation of the erosion to which the basin is subjected as a
result of the river flow, and further helps to prevent hydrologic
disasters in the possible risk zones. Among the various
experimental techniques in use for measuring the suspendedsolid
transport, nuclear methods have been preferably used
in this research, which are based on monitoring the concentration
of the suspended sediments. The suspended-solid
concentration is detected by the attenuation of radioactivity
emitted by a source of 241Am dipped in the water. This
attenuation, due to the presence of the sediments transported
in great amounts during events of flood is measured using a
scintillation detector made up of a crystal of NaI(Tl). With
appropriate calibration curves built both in the laboratory
and in the field, it is possible to trace the amount of suspended-
solid transport in a certain river section that is
located in the proximity of the river outlet. This methodology,
applied to different equipped basins in Italy and Africa,
is particularly useful for small and medium water courses
(similar to those of the Apennine ranges in Italy), allowing
an assessment of the erosion in the whole watershed. In this
note, the techniques used are introduced in detail, with
particular attention to the instrument calibration, and the
numerical results obtained for some basins in the Marche
region (Italy) are compared with some empirical formulae
used in previous reports for the calculation of erosion
Experimental methods for river discharge measurements: comparison among tracers and current meter
Full text linkWater and leachate tritium content as pollution tracer in sanitary landfill investigations
No full textScelta del tracciante ideale per indagini idrogeologiche: risultati preliminari da test in laboratorio
No full textTracers techniques are a good tool to investigate groundwater
dynamics; they are essential to perform measurement of hydrogeological
parameters of aquifers. This study was aimed at characterizing
adsorption, effective porosity and pore water velocity in soil
samples collected in a hydrographic basin of Marche Region (Italy).
This basin has the typical geologic and hydrogeological features of
many basins in Central Italy. Therefore. the principal aim is to
evaluate the best tracer to be used for hydrogeological purpose (i.e.
groundwater tracer test and aquifer parameter estimation). Adsorption
has been investigated by means of laboratory batch tests using
different tracers and involving different soils. In literature some application
of tracers both to laboratory scale and to field scale can be
found. Column tests have been performed also to test the effectiveness
of different test equipment and to investigate the influence of some
test parameters on the calculation of effective porosity and pore water
velocity. These considerations and test results are very useful to advise
the choice of the best tracer to be used in tracer field tests
Problems in the application of environmental isotopes to the hydrogeology of high mountain aquifers
Full text linkIn the present work some issues have been analysed, concerning
the application of environmental isotopes to hydrogeology
problems. Furthermore, a local meteoric water line for central Apennines
has been proposed, and an isotope altitude gradient, valid for
central Apennines, has been calculated by monthly rain samples.
The studied areas are located in central Apennines, and belong to
the Meso-cenozoic limestone ridge The main problems were related
to the effect of orography and climate on isotopic contents, and to
the hydrogeological complexity. In fact, in such zones the orography
led to meteoric precipitations having a peculiar isotope content.
Moreover, the occurrence of snowpack (especially in the Mt. Sibillini
area, at south), persistent even until late spring, caused the aquifers
to be recharged mainly by snowmelt; this fact brought to actual
variations in the isotopic contents of springs. For these reasons, the
sampling procedure and the location of rain and snow samplers took
on particular importance.
Finally, an application of isotopic data to some springs in Umbria
and Marche regions has been made and presented at the end of the
paper, to assess the suitability of the calculated gradient to define the
recharge elevation of aquifers. The obtained results underlined the
suitability of isotopes techniques for hydrogeologic purposes, especially
where the relationships among aquifers, the karstification and
the structural setting were quite complex but defined. In other cases,
with an even more complex hydrogeological setting a good interpretation
of the isotopic data is very hard. Further investigations will be
necessary to define the effectiveness of isotope techniques in such
complicated conditions
Location of recharge area of Gorgovivo Spring, Central Italy. A contribution from Isotope Hydrology
No full textMonitoraggio dell’inquinamento da discariche: metodi isotopici per individuare la presenza di contaminazione delle acque sotterranee
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