Context of project
Global approaches taking into account the human activities, the physical, biological and chemical processes, and the conflicts of interest, lay out new and complex questions for the territorial managers and the decision makers. This is particularly critical for areas going from the field to the landscape scale.
Decision-making tools for territorial management integrating complex specialized models are necessary to carry out diagnoses, to confront the different points of view, and simulate the evolutions of such complex system.
The objective of the SEVE project is to conceive and develop an integrated modelling approach which represents the functioning of continental surfaces (continuum formed by the ground, the vegetation, the water in circulation and the atmospheric boundary layer) at scales going from the field, to the catchments, and eventually to the regional scales.
Since the dilution in 2008 of the working group composed by French laboratories, the CESBIO has maintained a reduced team in order to follow SEVE development.
Work in cross
The current coupling implemented by CESBIO team include :
- a surface vegetation and atmosphere energy balance and water balance model (Braud et al. 1995),
- a three-dimensional variably saturated groundwater model (Ababou et al. 2006, Ababou and Al-Bitar 2008)
- and a heat transfer model in the ground (Boone 2000).
- a 3D radiative transfer model : DART (Gastellu- Etchegorry et al. 1996) is also used to generate spatialized data for the models.
Notice that socio economical models are yet to be included to the coupling.
The coupling is done by exchanging physicals variables between the different processes, but this exchange is not straightforward. Each process has a certain time scale and space discretization with a certain dimension (1D, 2D, 3D). In order to have a coherent approach existing models are extensively modified and split into several elementary models.
At the moment, we are able to simulate a simple catchment and a field of cultivated fruit trees within the framework of an experimental study. The simulations emphasis on the effect of spatial heterogeneity, this one is represented by the 2D distribution of the soil usage and vegetation description, the 3D modelling of the radiative transfers, the 3D description of the soil, and the root system. These coupled models is integrated in a data-processing architecture (PALM developed by CERFACS ensuring the exchanges of variables between models and objects in a multi-dimensional domain.
Future developments include the use of measurements from remote sensing data to force the models. Also this work opens many prospects for the simulation of basins and to the decision-making in case of multiple scenarios. Due to the flexibility of the platform performed, new processes can be plan to be included like surface runoff models, erosion, growth of vegetation, agricultural practices, pollutant transfers and socio-economical models.
Ababou R. and Al-Bitar A. 2008 Coupled surface/subsurface flow systems: numerical modelling. Book Chapter: Overexploitation and Contamination of Shared Groundwater Resources
Ababou, R., Al-Bitar, A., Peyrard, D., Quintard, M., Sanchez-Perez, J. M., Sauvage, S., Vervier, P., and Weng, P., 2006, modelling coupled surface/subsurface flow interactions: Implementation and comparison of three models based on Darcy, Boussinesq/Saint Venant, and Boussinesq/diffusive wave, with application to the Garonne floodplain, Midi-Pyrénées, France, in: Groundwater Hydraulics in Complex Environments, Proceedings IAHR-GW 2006, Toulouse, France, 12–14 June 2006.
Braud I., Dantas Antonino A.C., Vauclin M., Thony J.-L., Ruelle P., 1995. A Simple Soil Plant Atmosphere Transfer model (SiSPAT): development and field verification. Journal of Hydrology, 166, 213–250.
Gastellu-Etchegorry, J.-P., V. Demarez, et al. 1996. "modelling radiative transfer in heterogeneous 3-D vegetation canopies." Remote Sensing of Environment 58: 131-156.
Boone Aaron 2000. Modélisation des processus hydrologiques dans le schéma de surface ISBA: Inclusion d'un réservoir hydrologique, du gel et modélisation de la neige. CNRM, Météo-France. Toulouse III, Université Paul Sabatier: 252.