Essential Water Variables (EWVs) for the Water-Energy-Food (WEF) Nexus

,

• The GEOSS Water Strategy--From Observations to Decisions (Lawford et al., 2014) identifies several key water variables as Essential Water Variables (EWVs).This was based on broad metasurveys (Unninayar et al., 2010) of water-related observational needs for GEO Societal Benefit Areas (SBAs) that included energy and agriculture among others.• This paper summarizes currently defined EWVs required by key research and applications sectors involved in decision support within the Water-Energy-Food (WEF) Nexus.There is a notable overlap between the EWVs and a preliminary assessment of Essential WEF Variables.We also highlight EWVs that are relevant to the indicator monitoring objectives of the UN Sustainable Development Goals (SDGs), and GEOGLOWS priority thematic communities-especially those that overlap with the WEF Nexus.Besides primary EWVs such as precipitation, soil moisture, evapotranspiration and water levels/storage, supplemental EWVs are identified that support the integrated multi-sectoral information needed by WEF decision support applications.
Examples of supplemental EWVs include surface meteorology and winds, solar radiation, land use/land cover and vegetation.• Both Remote Sensing (RS) platforms and In-Situ observing networks are required to address the broad range of space/time resolutions, accuracies, and data latencies that end-users need.• The AGU-2021 is invited to comment on, endorse and/or recommend additional EWVs that should be considered for adoption by GEOGLOWS and the GEO (Group on Earth Observations).
• Critical EWVs are evident from the interaction between the water cycle and the atmosphere and land systems-including food and energy production • Capacity building for better monitoring, management, and maintenance of ecosystems and biodiversity they support; and to predict future changes • Disaster risk reduction, particularly for data exchange associated with early warnings and for the generation of regional products.
• Agriculture, associated with climate variability, climate change, and food security.
• Water, associated with the management approach of water resources and data management. EWVs Different uses/users of EWV data require very different space/time sampling and latency.
[Example for Soil Moisture specifications at 3 levels: Goal/Breakthrough/Threshold from WMO-OSCAR

Conclusions/ Recommendations
Conclusions: -EWVs need to address water cycle research and a broad range of end-user applications, especially the Water-Energy Food Nexus.
-EWVs are required at a range of observational space/time resolutions and latencies to monitor the global water cycle storages and fluxes, warn/predict extremes, and support strategic and operational decision-making of WEF resoirces.
To ensure the stability of existing systems and for the development of next-generation observational platforms, it is important that a concise set of EWVs required by WEF are recognized and adopted by international and national programs.

Recommendation:
-The AGU-2021 is invited to review, revise and endorse EWVs required by WEF for the consideration of GEOGLOWS and GEO (Group on Earth Observations) -Suggest next steps for the elaboration of more specific EWV observational requirements relevant to the WEF Nexus, including observing instruments and networks, data analytics and end user products for decision support systems.
AGU 2021, 13-17 Dec 2021 New Orleans, USA • Capacity building for better monitoring, management, and maintenance of ecosystems and biodiversity they support; and to predict future changes • Disaster risk reduction, particularly for data exchange associated with early warnings and for the generation of regional products.
• Agriculture, associated with climate variability, climate change, and food security.
• Water, associated with the management approach of water resources and data management.
EWVs Are Required For Supporting the Implementation of International Frameworks and Conventions

-
Sendai Framework for Disaster Risk Reduction: Understanding disaster risk; strengthening governance; investing in resilience; enhancing preparedness for effective response -The Ramsar Convention on Wetlands: Conservation and sustainable use of wetlands.Works closely with IUCN (conservation of nature), IWMI (Water management), Wetlands International, WWF/WWT -The Aichi Convention on Biological Diversity: Biological diversity; sustainable use of biodiversity; equitable sharing -The Framework Convention on Climate Change (UN-FCCC): Stabilize GHGs causing global warming; Prevent humaninduced interference w/climate system; linked to Aichi and Convention to combat desertification

-Sendai Framework for Disaster Risk Reduction: Understanding disaster risk; strengthening governance; investing in resilience; enhancing preparedness for effective response -The Ramsar Convention on Wetlands: Conservation and sustainable use of wetlands. Works closely with IUCN (conservation of nature), IWMI (Water management), Wetlands International, WWF/WWT -The Aichi Convention on Biological Diversity: Biological diversity; sustainable use of biodiversity; equitable sharing -The Framework Convention on Climate Change (UN-FCCC): Stabilize GHGs causing global warming; Prevent human- induced interference w/climate system; linked to Aichi and Convention to combat desertification Current List of Primary and Supplemental EWVs Followed by Tables Summarizing End-Users Served and Specifications of Requirements (Huffman et al., 2021) Primary EWVs Supplemental EWVs (apply to Water and related disciplines) Precipitation Surface meteorology Evaporation and evapotranspiration Surface and atmospheric radiation Snow cover (including snow water equivalent, depth, freeze thaw margins) Water vapor and clouds Soil moisture/temperature Permafrost Groundwater Land cover, vegetation, and land use Runoff/streamflow/river discharge Elevation/topography/bathymetry and geological stratification Lake/reservoir levels, water storage, and aquifer volumetric (or mass) change Surface altimetry Surface water extent Bathymetry Mass balances of glaciers and ice sheets Surface radiation Water quality Aerosols Water use/demand (agriculture, hydrology, energy, urbanization, others) Atmospheric radiation
• Water resources management • Biodiversity and ecosystem sustainability • Disaster resilience • Food security and sustainable agriculture • Climate change adaptation/mitigation • Clean energy and renewable energy • Water quality • Health and water/vector borne diseases • Severe weather and floods • Droughts and heat waves • Urban water management • Water stress and water use efficiency • Transboundary WEF policy

•
The GEOSS Water Strategy--From Observations to Decisions(Lawford et al., 2014)identifies several key water variables as Essential Water Variables (EWVs).This was based on broad metasurveys(Unninayar et al., 2010)of water-related observational needs for GEO Societal Benefit Areas (SBAs) that included energy and agriculture among others.•This paper summarizes currently defined EWVs required by key research and applications sectors involved in decision support within the Water-Energy-Food (WEF) Nexus.There is a notable overlap between the EWVs and a preliminary assessment of Essential WEF Variables.We also highlight EWVs that are relevant to the indicator monitoring objectives of the UN Sustainable Development Goals (SDGs), and GEOGLOWS priority thematic communities-especially those that overlap with the WEF Nexus.