Modelling of heat and mass transfer inside a traditional oasis: Experimental validation

Abstract

The traditional oasis is considered as an ecosystem with a particular properties. It consists of growing several crops such date palms, fruit trees and market gardening simultaneously on the same field. Although the nature of transport in oasis canopies is not fully understood, it is still possible to develop mathematical models, which generate realistic canopy microclimates. Throughout this paper, simple electrical analogues (Ohm's law) and empirical formulas are used to describe Dawn-to-dusk evolution of sensible and latent heat flux and to quantify biomass production inside a traditional oasis in the south of Tunisia. Temperature in and above the canopy also humidity, wind velocity, net, global and photosynthetic active radiation and sap flow within the xylem of date palm and fruit trees are included in the mathematical treatment. Those parameters were measured at different heights and the thermal budget was deduced. For validating our model, we have compared latent heat flux, sensible heat flux and biomass production predicted to, respectively, sap flow data, thermal budget and photosynthetic active radiation measured inside the oasis. We can signal a good behaviour of our calculus. The values simulated can be ameliorated to fit better those measured and the model can be used in general circulation models that require estimates of energy fluxes at a large scale if we can sweep more space by mobile sensors and if we use more sophisticated method to determine the geometrical structure of the trees inside the oasis and their stomata resistances.