Forest water balance model
- Silva Joint Research Unit
To accurately establish mass balance, in this case for water, it is necessary to:
Our water balance model is designed to account for a homogeneous area, generally one that measures 1 m2 or 1 square hectare. This system includes tree crowns and all soil layers containing root systems. Water fluxes are expressed in mm (1 mm = 1 L/m2).
This is largely defined as precipitation, but capillary rises should also be considered, notably if there is a water table. Lateral water fluxes (run-off or lateral drainage) might also exist, but the model will only consider conditions in which the in-flowing and out-flowing water fluxes for the plot are equal.
The results of these different types of fluxes either increase or decrease the total water content of the system found essentially in the soil (1).
|Water fluxes||Wet year (2006)||Dry year (2003)|
|Soil and herbaceous sublayer evaporation||45||46|
Aussenac G, Boulangeat C (1980) Interception des précipitations et évapotranspiration réelle dans des peuplements de feuillu (Fagus silvatica L.)et de résineux (Pseudotsuga menziesii (Mirb) Franco). Ann. Sc forest., 37(2), 91-107.
Bréda N, Huc R, Granier A, Dreyer E (2006) Temperate forest trees and stands under severe drought: a review of ecophysiological responses, adaptation processes and long-term consequences. Annals of Forest Science, 63, 625–644.
Courbet F, Doussan C, Limousin J-M, Martin-St Paul N, Simioni G (2022) Forêt et changement climatique - Comprendre et modéliser le fonctionnement hydrique des arbres. Editions Quae, collection Synthèses, 144 p.
(1) but not exclusively from soil: the different organs of the tree, mainly the sapwood of the trunk and to a lesser extent, the branches and roots, can act as an additional source of water in the case of drought. When the water stress is alleviated, this phenomenon can act in reverse.