Semiarid rangelands (grasslands with scattered trees and shrubs) are one of Africa’s most complex and variable biomes. They are a mosaic of land uses, where extensive livestock is the main economic activity, and agriculture, soil for livelihood, or conservational uses are also crucial. They are highly controlled by the availability of water, e.g., pasture and rainfed crop production. Although the vegetation is adapted to variable climatic conditions and dry periods, the increase in drought intensity, duration, and frequency, changes in agricultural practices and other socioeconomic and environmental factors precipitate their degradation. Through the integration of EO data into models, we can evaluate, on the one hand, the water consumed by semiarid ecosystems and their vegetation water stress and, on the other, its primary production. Thus, allowing us to assess the interaction of both processes, improving our knowledge about the vegetation’ behaviour in the face of drought. TACTIC will map water consumption and primary production of semiarid mosaic crop-rangelands at the optimal spatiotemporal scales, setting up an open-source cloud framework to monitor these processes’ interaction in the long term and analyse system tipping points. This information can help reduce the uncertainty associated with the administration and farmers’ decision-making processes.

Savannas are among the most complex, variable and extensive agrosilvopastoral systems on Earth. One fifth of the world’s population depend upon them (e.g. livestock, rural livelihoods). Droughts and erratic rainfall patterns across large parts of Spain (world) result in water-limited environments, sensitive to climatic conditions, environmental changes and land management practices, jeopardizing the ecosystem’s productivity and resilience. The aim of SWATCH is then, to develop an information system for quantifying savanna water use and biomass production on a regional scale, with the ultimate objective of supporting decision-making processes.

The Earth Observation (EO) data provided by Sentinel 2’s and Sentinel 3’s new missions will allow us to map the water use/stress and the invasive species distribution across the African savannas, as well as to monitor seasonal and long-term temporal variations.

To monitor savanna ecosystem water use/stress in a semi-continuous spatiotemporal way, this project integrates two different ET-estimation approaches, with different conceptual/operational capabilities and limitations. Kc-FAO56 (Allen et al. 1998), integrating reflectance-based “crop” coefficients, is used to derive unstressed savanna evapotranspiration (with high spatial resolution), and the two-source surface energy balance model (TSEB) (Norman, Kustas, and Humes 1995) integrating radiometric surface temperature allows the determination of water stress across savannas (with low spatial resolution).