Data collected during some successive field experiments, carried out in the natural sandy soil of the Hydrological Station of the Lido Beach of Venice during summer periods, suggest the following considerations on experimental and theoretical aspects.1)Evaporation may be evaluated using soil volumetric water content (q) profiles obtained by TDR technique.2)The two major stages of evaporation (atmosphere-limited and soil-limited stages) can be recognised only with the best possible vertical resolution of the TDR measurement (5 cm). Indeed, a superficial soil layer (about 20 cm) poorly equipped doesn't allow to measure properly the fast changes in soil volumetric water content (precipitation, strong solar heating and so on) and, of course, evaporation.3)Experimental soil moisture profiles trend shows a concavity change as the drying process goes on. This inflection may not be theoretically obtained by the solution of the diffusion equation with a constant diffusivity or with diffusivity being a monotonic increasing function of q. The solution presents the quoted inflection considering a non-monotonic diffusivity (presence of a minimum) or adding a source term to the diffusion equation. The problem has been studied considering different initial and boundary conditions, different diffusivity functions and possible source terms.

SOLUTION OF THE DIFFUSION EQUATION APPLIED TO DATA COLLECTED IN A NATURAL DRYING SOIL / Menziani, Marilena; Pugnaghi, Sergio; S., Vincenzi; L., Pilan. - In: MAP NEWSLETTER. - ISSN 1424-4853. - STAMPA. - 11:(1999), pp. 54-55.

SOLUTION OF THE DIFFUSION EQUATION APPLIED TO DATA COLLECTED IN A NATURAL DRYING SOIL

MENZIANI, Marilena;PUGNAGHI, Sergio;
1999

Abstract

Data collected during some successive field experiments, carried out in the natural sandy soil of the Hydrological Station of the Lido Beach of Venice during summer periods, suggest the following considerations on experimental and theoretical aspects.1)Evaporation may be evaluated using soil volumetric water content (q) profiles obtained by TDR technique.2)The two major stages of evaporation (atmosphere-limited and soil-limited stages) can be recognised only with the best possible vertical resolution of the TDR measurement (5 cm). Indeed, a superficial soil layer (about 20 cm) poorly equipped doesn't allow to measure properly the fast changes in soil volumetric water content (precipitation, strong solar heating and so on) and, of course, evaporation.3)Experimental soil moisture profiles trend shows a concavity change as the drying process goes on. This inflection may not be theoretically obtained by the solution of the diffusion equation with a constant diffusivity or with diffusivity being a monotonic increasing function of q. The solution presents the quoted inflection considering a non-monotonic diffusivity (presence of a minimum) or adding a source term to the diffusion equation. The problem has been studied considering different initial and boundary conditions, different diffusivity functions and possible source terms.
11
54
55
SOLUTION OF THE DIFFUSION EQUATION APPLIED TO DATA COLLECTED IN A NATURAL DRYING SOIL / Menziani, Marilena; Pugnaghi, Sergio; S., Vincenzi; L., Pilan. - In: MAP NEWSLETTER. - ISSN 1424-4853. - STAMPA. - 11:(1999), pp. 54-55.
Menziani, Marilena; Pugnaghi, Sergio; S., Vincenzi; L., Pilan
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/465787
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