Groundwater is one of the most important freshwater resources for mankind and for ecosystems. Assessing groundwater resources and developing sustainable water management plans based on this resource is a major field of activity for science, water authorities and consultancies worldwide. Due to its fundamental role in the Earth’s water and energy cycles, groundwater has been declared as an Essential Climate Variable (ECV) by GCOS, the Global Climate Observing System. The Copernicus Services, however, do not yet deliver data on this fundamental resource, nor is there any other data source worldwide that operationally provides information on changing groundwater resources in a consistent way, observation-based, and with global coverage. This gap will be closed by G3P, the Global Gravity-based Groundwater Product.
The G3P consortium combines key expertise from science and industry across Europe that optimally allows to (1) capitalize from the unique capability of GRACE and GRACE-FO satellite gravimetry as the only remote sensing technology to monitor subsurface mass variations and eventually groundwater storage change for large areas, (2) incorporate and advance a wealth of products on storage compartments of the water cycle that are part of the Copernicus portfolio, and (3) disseminate unprecedented information on changing groundwater storage to the global and European user communities, including a European use case as a demonstrator for industry potential in the water sector. In combination, the G3P development is a novel and cross-cutting extension of the Copernicus portfolio towards essential information on the changing state of water resources at European and global scales. G3P is timely given the recent launch of GRACE-FO that opens up the chance for gravity-based time series with sufficient length to monitor climate-induced and human-induced processes over more than 20 years, and to boost European space technology on board these satellites.
G3P aims at developing a product of groundwater storage variations with global coverage and monthly resolution from 2002 until present by a cross-cutting combination of GRACE and GRACE-FO satellite gravity data with water storage data that are based on the existing portfolio of the Copernicus services. This global gravity-based groundwater product (G3P) is developed for later operational implementation as Essential Climate Variable (ECV) Groundwater into the Copernicus Climate Change Service, Lot Land hydrology & cryosphere. Specific objectives within this overall project strategy include:
- Processing and making accessible the latest satellite gravity data, in particular of the recently launched GRACE-FO mission, as water storage products, including the exploitation of the added value of the new Laser Range Interferometry (LRI) technique on board of GRACE-FO for improved hydrological products
- Setting-up the groundwater product as a new cross-cutting application of the existing product portfolio of three Copernicus core services, i.e., combining products of the Global Land Monitoring Service (snow water equivalent, soil water index, river water levels), the Copernicus Climate Change Service (C3S) (surface soil moisture, glacier mass changes, lake water level), and the Emergency Management Service (river discharge and simulated storage compartments).
- Advancing existing Copernicus service products to match the requirements for the cross-cutting groundwater application developed in this project, in terms of their information content and spatial or temporal coverage
- Developing and evaluating the performance of a new G3P-based Groundwater Drought Index as an exemplary use case for Southern Spain.
- Assessing to which extent environmental change and human water use affects the global groundwater resources and the status of large aquifers worldwide.
IGRAC is directly involved in Work Packages (WP) 4: “Groundwater product development, evaluation and service preparation” and 5: “Dissemination, exploitation and use cases”.
In WP4, IGRAC will evaluate and select aquifers for calculating and making available to the public area-average groundwater storage time series of G3P, and a sub-set of those aquifers will be used for the evaluation of G3P against in-situ observations. A validation will be made after transformation of in-situ groundwater levels to area-average groundwater storage time series or by other statistical approaches. In-situ data will be collected from different sources, and public data stored in GGMN will be used as well.
For WP5, where IGRAC is the lead beneficiary, tasks include the integration of the G3P product into GGMN, and the preparation of a Groundwater Resources Assessment report combining the G3P outcomes and information collected in WP4 and considering limitations and opportunities of new G3P information.
The dissemination of G3P results is another important task of WP5 including all partners. G3P will be promoted as a component of GGMN and as such, it will be part of GGMN trainings, workshops, presentations, conferences, and promoted further through all IGRAC and partners channels and networks.