55,952 research outputs found
Domains of spit evolution in the Goro area, Po delta, Italy
No full textGoro lagoon was formed during the 19th century in the southern part of the Po Delta. Its origin is related to the growth of a spit system, which progressively occluded the southernmost interdistributary bay from the sea. The development of the spits is due to the morphological prominence of the Po Delta which causes a divergent littoral drift, enhanced by wave refraction over the delta front. During the last century the spit was abandoned, destroyed, and re-constructed several times because of the development of newer spits seawards. Using historical maps and aerial photographs, three different periods are recognised, featuring distinctive spit growth styles: parallel, fan-shaped and branched. The different domains of spit evolution are related to several factors, mainly to the mutual influence of sediment discharge, sand mining along the Po river, wave action over the delta front, human-induced subsidence and direct human interventions along the spits and for flood-control
Improved gravitational grain size separation method
No full textA low energy method for grain size separation in heterogeneous sediments without using chemicals and in thermostatic condition, was tested in order to preserve unchanged the physical and chemical properties of the porous medium. The method consisted of wet sieving, to divide the sandy fraction from the fine fraction (< 63 μm), and of wet gravitational separation to divide the clayey from the silty fraction. Deionised water was used as dispersive phase for sequential gravitational separation of silt and clay. Stokes' law was applied to calculate the settling time for the silty fraction in order to siphon out the resulting supernatant containing the clay particles. The procedure was systematically tested and proved to be highly reproducible and the degree of purity was 90% for silt and 95% for clay. This method can be conveniently applied in many studies on contaminant fate and partitioning between liquid and solid phases, where physical and chemical integrity of each granulometric fraction is a prerequisite. © 2010 Elsevier B.V
The influence of disaggregation procedures on soil gravitational separation
No full textThe use of dispersants in particle size analysis is a common practice, but this could cause bias on the gravitational separation of the different particle fractions in natural soil. The study highlights the results obtained in gravitational separation of silty and clayey fractions by using hydrogen peroxide (H2O2) and sodium hexametaphosphate ((NaPO3)6) in different combinations. The efficiency of the different treatments was verified by comparison against the results obtained on the same sediments without any treatment. The separation method is based on Stokes law to calculate the settling time of particles in deionized water under controlled temperature. This method was applied to three different agricultural soils of the Po River Plain. The sample treated with H2O2 and (NaPO3)6 at 4% showed the best results in terms of particle size degree of purity, ranging from 95% to 97% for clay and from 91% to 95% for silt. The degree of purity indicates the percentage of sediment with the particles of the provided grain sizes. © 2014 Elsevier B.V
Natural and man-made coastal change of the Goro spit-lagoon system (Po Delta, Northern Italy)
No full textEvaluation of floodplain changes and geomorphological mapping of the coastal zone plain of Myzeq (Albania) using Landsat TM imagery
No full textStudio delle pianure alluvionali in Albani
Evaluation of floodplains change and geomorphological mapping of the coastal zone plain of Myzeq (Albania) using Landsat TM imagery.
No full textValutazione integrata, a fini gestionali, delle dune costiere: metodologia e caso studio
No full textNuovo metodo per los tudio dei sistemi dunal
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