A scaling procedure for straightforward computation of sorptivity
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2021-09-22Referencia bibliográfica
Lassabatere, L... [et al.]. A scaling procedure for straightforward computation of sorptivity, Hydrol. Earth Syst. Sci., 25, 5083–5104, [https://doi.org/10.5194/hess-25-5083-2021], 2021.
Patrocinador
French National Research Agency (ANR) European Commission ANR-17-CE04-010Resumen
Sorptivity is a parameter of primary importance in
the study of unsaturated flow in soils. This hydraulic parameter
is required to model water infiltration into vertical soil
profiles. Sorptivity can be directly estimated from the soil hydraulic
functions (water retention and hydraulic conductivity
curves), using the integral formulation of Parlange (1975).
However, calculating sorptivity in this manner requires the
prior determination of the soil hydraulic diffusivity and its
numerical integration between initial and final saturation degrees,
which may be difficult in some situations (e.g., coarse
soil with diffusivity functions that are quasi-infinite close to
saturation). In this paper, we present a procedure to compute
sorptivity using a scaling parameter, cp, that corresponds to
the sorptivity of a unit soil (i.e., unit values for all parameters
and zero residual water content) that is utterly dry at the
initial state and saturated at the final state. The cp parameter
was computed numerically and analytically for five hydraulic
models: delta (i.e., Green and Ampt), Brooks and Corey, van
Genuchten–Mualem, van Genuchten–Burdine, and Kosugi.
Based on the results, we proposed brand new analytical expressions
for some of the models and validated previous formulations
for the other models. We also tabulated the output
values so that they can easily be used to determine the actual
sorptivity value for any case. At the same time, our numerical
results showed that the relation between cp and the
hydraulic shape parameters strongly depends on the chosen
model. These results highlight the need for careful selection
of the proper model for the description of the water retention
and hydraulic conductivity functions when estimating sorptivity.