| Evapotranspiration (ET) is a major component of the hydrological regime in boreal ecosystems. It is known that ET varies both spatially and temporally, and is affected at the mesoscale by such factors as topography, soil properties and vegetation. A physically based approach which takes into account these factors must therefore be used in order to better understand and accurately represent the variability of actual ET. A distributed hydrological model called WATFLOOD, which can simulate actual ET based on the Priestley-Taylor approach (W-PT), was used to model the hydrologic cycle in a boreal ecosystem. To that end, three modelling scenarios, each based on different combination of input data sources, were scrutinized using W-PT. The watersheds under study, which are located within the limits of the BOREAS region, cover a total area of approximatively 100 000 sq. km. They encompass the Southern and Northern Study Areas (SSA and NSA), as well as the transect connecting these two areas. The objective of this research being to model spatially distributed evapotranspiration at the mesoscale, special care was taken to represent as accurately as possible the spatial and temporal variations of the radiative fluxes, a variable required by Priestley-Taylor model. (Abstract shortened by UMI.)... |
