The combined quantity of significant volumes of water in confined and un-confined aquifers. In the case that a groundwater body straddles two or more reporting basin districts, then the groundwater body should be sub-divided per district. Metadata: https://environmentlive.unep.org/media/docs/projects/metadata_6_6_1.pdf, https://unstats.un.org/sdgs/metadata/files/Metadata-06-06-01a.pdf, https://unstats.un.org/sdgs/metadata/files/Metadata-06-06-01b.pdf