SWOT and the global dynamics of water supply, demand, and scarcity

Principle Investigator: Colin Gleason (UMass Amherst)

Co-Investigator(s): Casey Brown, Chaopeng Shen, Kostas Andreadis

Collaborator(s): Yoshihide Wada, Cauce Bajio

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Our team believes that one of SWOT's greatest hydrologic revolutions will be its ability to resolve humans' role in the water cycle. Humans modify, accelerate, and interrupt the natural hydrologic cycle, but our actions are poorly represented in current global hydrologic practice. SWOT's piercing hydrologic vision finely resolves rivers and lakes regardless of ground politics, access, or remoteness, and everything it sees has been impacted by humans either directly or indirectly. Therefore, humans must be explicitly represented in any truly global hydrology learned from SWOT.

SWOT has come of age at the exact same time as explainable ML. We can deploy SWOT's essential primary data with the skill of ML while honoring a century of process knowledge in hydrology to accurately quantify the human hydrologic system. The SWOT River Database (SWORD, Altenau et al., 2021) is also a powerful unifying framework that topologically organizes the land surface into meaningful units to humans- rivers and reservoirs, not grid cells. We therefore propose a global framework for finally quantifying human water use in the context of natural hydrologic cycles on the over 200,000 SWORD reaches and reservoirs around the world. We will bring GRACE-FO, SMAP, and future NISAR to SWORD to integrate all of these direct observations of hydrology into a single SWOT-centered human-hydrologic framework. This framework will allow the interrogation of a thousand hypotheses currently impossible to investigate, and we believe that the time has come to explicitly define SWOT's next generation hydrologic world as one where humans are complicit in every water and energy flux we model.

To that end, we have three goals:

1. Quantify human water use across all SWORD reaches + reservoirs using differentiable ML
2. Map global water scarcity at the reach scale
3. Serve the SWOT ST by continuing to operate, improve, and maintain Confluence