Ecohydrological changes in the Murray-Darling Basin. II. Development and tests of a water balance model.
The hydrological part of the FOREST-BGC model was originally developed to estimate evaporation (ET) loss from coniferous forests in the USA. Application of the model to eucalyptus communities in the Murray-Darling Basin (MDB) in Australia required modification and testing of the model. A soil evaporation component was added and leaf water potential, originally expressed as a function of soil water content (given as a fraction of field capacity), was altered to reflect soil water potential. To model better the interaction between the evaporation of free intercepted water from the canopy and transpiration, the model was modified to reflect the suppression of transpiration by a wet canopy. The modified model was tested against data from two Australian plant communities. The first data set was a lysimeter study of water loss from a coastal eucalyptus forest; the second soil moisture data set was from a semi-arid eucalyptus woodland in the MDB. Predicted soil water deficits agreed well with observed values in both systems. The study demonstrated the potential of such a model for estimating how changes in land cover or climate might affect local and regional water balances.