Tracking the Water Cycle from Space: Novel Insight into Water Availability for Global Croplands

Feb 20, 2024

By Yan Jiang

Water availability supports life on Earth and all ecosystem functions. Yet, hazards such as droughts and storms pose significant threats to food, energy, and infrastructure, leading to billion-dollar losses. Advances in satellite remote sensing have enabled new insight into the structure and complexity of the water cycle, with the potential to directly inform actionable solutions for water scarcity. My research employs advanced satellite remote sensing to investigate sub-seasonal hydroclimatic variations, water-related hazards, and water availability for agriculture. This talk will highlight my innovative use of satellite water isotope observations to track atmospheric moisture sources and movement through the hydrological cycle over global croplands. Our measurements find that land evaporation can contribute up to 70% of atmospheric moisture during the growing season over a few critical breadbaskets. Integrating this with crop phenology data, we find strong variations in crop sensitivity to moisture sources at critical growth stages. In particular, for croplands that rely on land-based moisture (over 40% of moisture originating from land evaporation), we are able to observe that rainwater supply often falls short during the reproductive stage, leading to extra depletion of root zone soil moisture (RZSM). Our findings underscore the importance of -- and the promise of satellite for -- considering moisture origins, rainwater supply and RZSM for different crop phenology stages to understand annual yield variances, particularly for maize and winter wheat. These insights are pivotal for informing effective water monitoring, smart irrigation strategies, and potential adaptation responses including protection of upstream land moisture sources to achieve food security.

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