What is it about?

Combining observations and model results, we show that soil salinization does affect the long-term soil-water balance of saline river basins, eventually acting as an aridity enhancer. The strength of this control depends on the capability of vegetation to cope with salt stress through specific functional traits – i.e., salt tolerance – and is key to the understanding of vegetation-water relations in arid and transitional watersheds. Our approach can also be applied to infer crucial data about the salinization level and vegetation salt-tolerance of river basins. Such information is essential to develop reverse-engineering measures to mitigate catchment-scale aridity and salinization, based on salt tolerance plant traits.

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Why is it important?

Our model explicitly accounts for the effects of salinity on evapotranspiration and the species-specific character of these effects and allows us to explore vegetation-water relations in saline watersheds across a wide range of climatic and salinization conditions. Salinization is shown to pose an additional energy limitation on evapotranspiration, and this control appears to be the strongest in transitional and wet sub-basins, where the impairment of ET due to osmotic effects is potentially more significant than in already arid and hyper-arid climates. Moreover, our approach can be used to obtain crucial information on salinization and vegetation salt tolerance at the basin scale – which is still extremely challenging to obtain through classic observational techniques and remote sensing. It can then be pivotal to the future management of salt-affected basins.

Perspectives

Salinity is a crucial and yet understudied, hydrological driver. This paper sheds some light on salinity effects at the river basin scale and their role in shaping land-atmosphere interactions.

Annalisa Molini
Khalifa University of Science Technology and Research

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This page is a summary of: River basin salinization as a form of aridity, Proceedings of the National Academy of Sciences, July 2020, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2005925117.
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