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Fifth National Climate Assessment - Read the Report

Interagency Integrated Water Cycle Group

The integrated water cycle involves the movement of water among the ocean, atmosphere, land, biosphere, and cryosphere, including interactions with human activities. Understanding the effects of global change on the integrated water cycle, including its alterations, impacts, and interactions across scales, requires interdisciplinary and interagency approaches.

USGCRP’s Integrated Water Cycle Group (IWCG, or “the group”) coordinates research that will help us better understand the effects of global change on the water cycle and the impacts of those changes through collaborative, interdisciplinary approaches. The IWCG seeks to develop interagency approaches to advance fundamental understanding and produce actionable science and results related to the integrated water cycle. This requires the IWCG to maintain an end-to-end, multi-scale perspective that connects agencies’ fundamental research and capabilities with applied research and efforts that ensure the scientific insights these produce are translated to actionable information communicated to decision-makers, ensuring close coupling and open lines of communication among the various research communities. 

The IWCG seeks to

  • Coordinate research relevant to understanding the integrated water cycle, how it changes in response to short-term and long-term perturbations, and the associated local, regional, and global impacts of those changes;

  • Advance capabilities and research infrastructure that support water cycle observation, modeling, and predictability at a range of scales; and

  • Develop approaches to apply and translate our understanding and inform decisions concerning resilience and water security.

The IWCG consists of federal agency representatives (from current USGCRP agencies and the broader federal landscape) and interested SGCR Principals. The full group meets quarterly or at a frequency decided by the members. IWCG features two active workstreams that meet on a monthly basis: Hydrology and Watershed Systems (HWS) and the U.S. Global Energy and Water Exchanges (GEWEX). 

To learn more about IWCG, please contact Yishen Li, the USGCRP Water Cycle Science Coordinator and IWCG Coordinator.

Hydrology and Watersheds Subgroup

The Hydrology and Watershed System (HWS) Subgroup aims to advance capabilities and infrastructure that support water cycle observation, modeling, and predictability at various scales. Topics of interest include but are not limited to

  • local watershed perspectives to higher spatial and temporal scales

  • hydrologic model structure and modularity

  • observation and analysis methods for changing hydrologic systems

HWS actively engages the Integrated Hydro-Terrestrial Modeling (IHTM) initiative to build national capacities for multi-agency data and simulation products that provide the basis for understanding and managing complex water systems. USGCRP hosted the second IHTM workshop (IHTM 2.0) in Reston, Virginia, and virtually on October 31 - November 2, 2023.

HWS meets monthly to exchange the latest science, products, and programs by guest speakers from the U.S. federal and non-federal water cycle science community. Recent presentations include:

  • USGS National Hydrologic Geospatial Fabric and National Hydrologic Model

  • Climate change effects on federal hydroppower and DOE assessment under the SECURE Water Act

  • USGS National Water Availability Assessment

  • Inland waters and carbon biogeochemistry

  • FEMA's Future of Flood Risk Data Initiative

HWS members also contribute to a Report to Congress for the long-term research and monitoring program of the Western U.S. Hydroclimatology Program. 

U.S. GEWEX Subgroup

The USGCRP established the U.S. GEWEX workstream in September 2019.

The U.S. GEWEX supports U.S. interagency efforts, focused on federal water and energy cycle research, that align scientifically with the GEWEX core project of the World Climate Research Programme. It exists under the auspices of USGCRP to provide infrastructure and support for U.S. interagency activities relevant to water cycle science and global change, under the direction of the IWCG.

The U.S. GEWEX facilitates the coordination of interagency activities within the IWCG, through regular discussions and meetings of program managers from the various USGCRP agencies interested in science relevant to GEWEX. This program manager group is chaired by two program managers (currently from NASA and DOE) and coordinated by the U.S. GEWEX.

Interagency activities are undertaken with the goal of an enhanced predictive understanding of the water cycle and energy fluxes of the changing Earth and global climate system, using satellite and surface-based observations, global and regional process-resolving models, and the resulting diagnostics and data. The focus on water cycle and energy exchange is predominantly on multiscale atmospheric processes and surface-atmosphere interactions at various scales, including phenomena such as local recycling of water, moisture transport, cloud-precipitation interactions, and changes to radiative balance.

The U.S. GEWEX coordinates with the program manager group to support activities that address scientific objectives including (but not limited to) understanding and prediction of current and future water cycle extremes; land-atmosphere interactions; the role of clouds in a changing water cycle; teleconnections between water cycle phenomena and changes in other parts of the Earth system (e.g., how changes in the Arctic may affect mid-latitude storms); and the impacts of large scale human-Earth system interactions (e.g., land management and irrigation) on regional and global water cycles.

U.S. GEWEX Activities

NOAA-DOE Precipitation Processes and Predictability Workshop

Our ability to predict when, where, and how much precipitation will fall is critical for decision making and responding to the impacts of extreme rainfall across a wide range of sectors and timescales. The current generation of Earth system models (ESMs), however, have large and persistent systematic errors that severely limit the ability to faithfully reproduce the many spatial and temporal scales of precipitation variability.

The NOAA-DOE Precipitation Predictability and Processes Workshop was held virtually during November 30−December 2, 2020. In partnership with USGCRP and the U.S. Climate Variability and Predictability Program (US CLIVAR), the workshop was attended by participants from the observational and modeling research communities as well as operational centers to address the challenge of precipitation predictability. More specifically, the workshop focused on precipitation predictability and physical processes for the contiguous United States with an emphasis on sub seasonal to multi-decadal timescales. Essentially, the workshop asked how we can improve our ability to predict precipitation variability and extremes.

Learn more in the workshop report.

Global Precipitation Experiment

U.S. GEWEX is proposing an activity that enhances the predictive understanding of precipitation. One such activity could be the Global Precipitation Experiment (GPEX), which will systematically and comprehensively work on reducing model biases in global coupled models and improve precipitation prediction using an integrated observations and modeling strategy to target critical processes and phenomena.

GPEX will officially launch as a new lighthouse activity at the 2023 World Climate Research Programme (WCRP) Open Science Meeting. GPEX aims to accelerate advances in precipitation knowledge and prediction at different temporal and spatial scales, enhance public access to relevant datasets, and benefit society, all by coordinating national and international activities. Member agencies of the U.S. GEWEX Subgroup are supporting the domestic and international coordination of GPEX implementation as a multi-year project.

Learn more with the GPEX Tiger Team presentation to WCRP.

Hydroclimate Activities

U.S. GEWEX is engaged in several active or planned topics on hydroclimatology. These efforts include but are not limited to

  • a two-part mini-workshop on soil moisture from 2021 (see below)

  • a proposed mini-workshop on ecohydrology

  • a proposed mini-workshop on extreme events, particularly flash droughts, and

  • regional hydroclimate topics, such as mountainous hydroclimate studies and solutions and engagements with the U.S. Regional Hydroclimate Projects.

Soil Moisture Mini-Workshop #1

Soil Moisture Mini-Workshop #2