Integrated modelling of the water cycle in semi arid watersheds based on ground and satellite data: the SudMed project

The arid and semi-arid regions of the Mediterranean basin correspond to geographical surfaces with strong demographic growth. They are of great importance because of the scarcity of the water resources available.

Due to low precipitations, irrigation located in plains is by far the major consumer of water, whereas water resources are issued from limited mountainous areas supplying plain aquifers and river flows. The growth and the transformation of the needs of the populations intensify the impact of the activities of the man on his medium and can generate phenomena which degrade the environment. This phenomena can be amplified by the climatic changes, and their feedbacks can be global or regional. Efforts are necessary to improve models to understand and predict the impact of the past and forthcoming environmental and human changes on the hydrological cycle in arid and semi-arid regions.

 

• Context of the SudMed project :

Sustainable management of the water resources for catchments typical of the South of the Mediterranean area associating mountainous water tower, and intermediate zone of transfer with transient storage (dams or lakes) where the rainfed agriculture and the irrigated zones, which mobilize 80 % of the available water resources, dominate.

The ambition of this program is to develop methodologies which permit the integration of ground-based data, process models, and remotely sensed satellite data in order to document, understand and predict the evolution of a semi-arid heterogeneous region for a sustainable development.

The scientific approach is based on the synergy between the mathematical modelling and the satellite and in situ observations.

In this context, the SUDMED program has been launched in 2002 to address the issue of improving our understanding of the hydrological functioning of the Tensift watershed, a semi-arid basin located in central Morocco. Apart from the Tensift major site, the SudMed project extended in 2007 to the Yaqui valley, North-West of Mexico, where similar bioclimatic and agricultural conditions are found. Since 2008, an experiment is also running in Tunisia, in the Merguellil catchment (2000 km2) Substantial results have been obtained since 2002. The program is still going on, with focus on the following thrust areas: integrative modelling at watershed scale, integration of various types of remote sensing data in models (microwave, thermal), aggregation and desegregation of low resolution data, finalization of tools for operational management, and producing biophysical variables and indicators at the Mediterranean scale.

In the coming year, in the continuity of the activities led within the framework of the SUDMED program, this project will extent to the Middle East, in the Orontes watershed extending between Lebanon and Syria. Focus will be put on snow on the Lebanon side, and on irrigation in Syria. All sites, including existing ones, will support a regional approach for providing agro-hydrological indicators at the Mediterranean scale. The CESBIO is a partner of the "Continental Surfaces and Interfaces in the Mediterranean Area" (SICMED) program

CESBIO sites (SudMed)

• The scientific objective is twofold :

(1) to improve our understanding of the main processes of the water redistribution at the catchment scale through the development of a numerical platform of modelling and observation in order to establish evolution scenarios of the water resources in a changing climate context and

(2) to get a better understanding of the terrestrial water cycle at the continental scale and in particular, the linkages between the continental water cycle and the large scale climate pseudo-oscillations.

This program is based on remote sensing conventional measurements, geographical information systems and models (surface functioning...)

synergy between in situ observations, mathematical modelling and remote sensing data

These objectives articulate around :

with a specific focus on

• Our partners

  • L'Agence de Bassin Hydraulique du Tensift :(ABHT)
  • Direction de la Météorologie Nationale (DMN)
  • The Cadi Ayyad Marrakech university (UCAM) is the academic partner of this project.
  • L' Office de Mise en Valeur Agricole du Haous (ORMVAH)
  • Institut national agronomique de Tunisie (INAT)
  • Ecole Nationale d’ingénieurs de Tunisie (ENIT)

 

• Conclusion

the research carried out within the SudMed project since 2002 led to significant results for the monitoring of the irrigated plain and gave a first glimpse of the complexity of the hydrological processes in the High Atlas ; however, more work is needed to reach our objective, i.e. to fully understand the integrated hydro-ecological functioning of this type of basin.

The program is still going on, with focus on the following thrust areas:

• integrative modelling at watershed scale,
• integration of various types of remote sensing data in models (microwave, thermal),
• aggregation and desegregation of low resolution data,
• finalization of tools for operational management,
• and producing biophysical variables and indicators at the Mediterranean scale.

Therefore, future research include at least three major points :

1. extending the Mediterranean number of sites ( Lebanon and Syria in 2010), all sites will support a regional approach for providing agro-hydrological indicators at the Mediterranean scale.
2. extending the monitoring by using routinely available low resolution data (MODIS, SPOT-VGT, MSG…) in order to assimilate jointly TIR, microwaves and NDVI data
3. all this research will contribute to prepare the next space missions