Methodology

Latent heat flux for the Valmasino watershed was estimated as a residual term of the one-dimensional surface energy balance equation following the procedure schematised in Figure 2.

Figure 2. Bock diagram illustrating the overall methodology

The methodological approach is specifically based on the direct use of remote sensing derived information for watershed characterisation and modelling. Satellite data were used to extract the land cover map of the area in the two seasons and to retrieve the geophysical parameters controlling the soil-vegetation-atmosphere processes.

Meteorological measurements were spatially distributed taking into account the DEM. Vegetation characteristic parameters vary spatially with the cover type, therefore the watershed was stratified into different vegetation classes in order to assign to each class the corresponding value of vegetation height, vegetation fractional cover and surface emissivity.

Satellite extracted geophysical parameters, meteorological data and vegetation related parameters were integrated in a GIS (Geographical Information System) environment to evaluate energy balance components and daily evapotranspiration at the catchment scale.

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