EU - G3P - Global Gravity-based Groundwater Product

Groundwater is a major source of water supply in most regions worldwide. Understanding the amount of groundwater that is available for use is crucial for sustainable water management. Climate change, in turn, has an impact on the amount of groundwater recharge and thus on the renewable water resources. Indirect climate change impacts such as land use changes and intensification of human activities may increase the demand for groundwater. Groundwater is one of key parameters of the Earth system and essential to characterise the state of the global climate system, and as such on the list of 'Essential Climate Variables' (ECVs) as defined by the Global Climate Observing System (GCOS). The EU Water Framework Directive and other water-related Directives [… add on the relevance of groundwater]. [Add on economic relevance of groundwater resources]. However, these needs for groundwater monitoring and management are undermined by the limited availability of groundwater observations in particular for large areas [trans-boundary aquifers] from ground station networks, with low stations density and decreasing number of stations in many regions worldwide. The only available observation technology that allows for large-scale monitoring of subsurface water storage variations is satellite gravimetry. By monitoring changes of Earth’s gravity field, the satellites of the GRACE (2003-2017) and GRACE-FollowOn (since 2018) missions are sensitive to the mass effect of groundwater storage changes. While operational Copernicus Services (Global Land Monitoring Service, Climate Change Service) provide products on ECVs related to the terrestrial water cycle such as soil moisture, snow cover, lake water levels, there is no Copernicus product yet that quantifies the ECV groundwater, neither on global nor on European or regional scale. Furthermore, there is no global freely available and consolidated data set on groundwater storage variations based on satellite gravimetry yet.