Theia Drought Scientific Expertise Centre (SEC) bring together teams from the CESBIO and CNRM in Toulouse, the IGE in Grenoble and Hydroscience Montpellier (IRD). Its ambition is to develop a drought monitoring tool combining the quantification of the hazard (lack of water) with the vulnerability (impacts) based on Earth observation data. Research and activities will be carried out in close cooperation with Theia Soil Moisture SEC.
Two development phases are foreseen:
In a first one-year phase, the objective is to build a drought index. A database covering at least ten years will be set up and systematically updated as data becomes available. It will include several drought indices:
- deviations from the mean, normalized by the maximum amplitude or by the standard deviation of the variable, informed by soil moisture products ( SMOS CATDS Theia Moisture of the root zone, ASCAT,…) the Normalized Difference Vegetation Index (NDVI) as an indicator of vegetation vigour and the difference between air temperature and soil temperature (Ts-Ta);
- The PrISM product developed in collaboration between the IGE and CESBIO, using SMOS soil moisture to constrain, in real time, a satellite precipitation product. This avoids waiting for the unbiased version of the satellite product, which is often available several weeks after the measurement. The drought index will be constructed on the basis of the probabilistic Standardized Precipitation Index (SPI). All drought indices will be compared with indices from the outputs of the LDAS-world (Météo-France). All drought indices will be compared with indices from the outputs of the SIM model (Météo-France).
In summary, the products provided in the first phase will be the following:
- An updated database available via Theia.
- An operational product of drought index on a global scale derived from SMOS Soil Moisture in the Root Zone via CATDS and Theia.
- A real-time drought index based on the PrISM satellite precipitation product and the SPI index.
- A web-based data mining tool (see for example the FREDI online application: http://osr-cesbio.ups-tlse.fr/fredi/ or http://hydroweb.theia-land.fr).
The second phase will be initiated during the first year through meetings with partners within Theia Drought SEC and consultation with potential users. Depending on the needs expressed and the progress of the research work, certain avenues will be explored such as, for example, temporal and spatial resolutions, the notion of a tailor-made drought indicator, the dichotomisation of the space to be qualified, duration and intensity of the drought, surface area affected, etc.
Theia Drought SEC will provide global and regional products on hazard, and will quantify the risks in areas for which it already has expertise: the Mediterranean basin, the state of Karnataka (India) and the Sahelian zone in the first instance.
2021 : Drought hazard assessment, setting up of the database, development of indicators, setting up of a scientific animation.
2022-2023: Production of a web interface, development of a Drought Risk Index, continuation of scientific animation.