Unraveling interactions between WATER and carbon cycles during drought and their impact on water resources and forest and grassland ecosySTEMs in the Mediterranean climate

 Period: 2022-2024 (36 months)
Partners: The consortium is based on a close collaboration between 5 partners:

  • Consiglio Nazionale delle Ricerche – Istituto di Ricerca per la Protezione Idrogeologica (CNR-IRPI)
  • University of Florence
  • University of Trento
  • University of Campania (Luigi Vanvitelli)
  • University of Basilicata


Mediterranean mountainous basins provide critical water supply and ecosystem services, yet these environments are increasingly at risk due to anthropogenic stressors and competition for water across urban, agricultural and environmental demands. On the top of this, future climate projections suggest a drier and warmer Mediterranean with large increases in the frequency, duration, and severity of hydrological droughts (i.e., runoff and groundwater levels below than normal) with serious consequences for the management of water resources and natural ecosystems.
In spite of the recent progress in land surface monitoring, current drought estimation in widely used operational products still largely relies on poorly parameterized potential evapotranspiration, in combination with simple hydrological bucket models (e.g., drought indices) which have shown to lead to questionable results.
As hydrological systems are intrinsically intertwined with climatological and ecological systems, the propagation of meteorological droughts (i.e., precipitation below than normal and higher temperatures) through them is modulated by a variety of mechanisms which are linked to carbon and water cycle interactions and specifically to how different plant species i) access subsurface water storages and ii) respond to water stress, high CO2 and high evaporative demand. Ignoring the parameterization of these mechanisms is often the norm in state-of-the-art land surface and hydrological models and impacts water balance closure via incorrect representation of transpiration leading to uncertainties in hydrological drought prediction.
The ultimate goal of WATERSTEM is to unravel the interactions between carbon and water cycles as to understand the modulating effect of the vegetation on water-supply deficit (as opposed to the more frequently addressed meteorological drought) and its impact on water resources and natural ecosystems in Mediterranean climates. The work plan will focus on six Mediterranean mountainous basins and will employ a novel combination of field monitoring (water stable isotopes, tree ring analysis and geophysical measurements), remote sensing, data assimilation and ecohydrological models. WATERSTEM will develop a multidisciplinary and novel conceptual framework that will be used to translate the acquired scientific knowledge into practices to support water resources and silvopasture management across a variety of Mediterranean climates and physiographic settings.
This is the core research of WATERSTEM, which is intimately coupled to the concept of Critical Zone (CZ, the Earth’s permeable near-surface layer from the top of the trees to the bottom of the groundwater, where rock, soil, water, air, and vegetation interact and sustain life) that is fundamental for understanding and predict: i) hydrological droughts, ii) episodes of vegetation mortality (e.g., forest dieback) and iii) whether natural ecosystems may become a source or sink of carbon during drought.