however larger countries may have more general information overall given the more detailed monitoring of groundwater hotspots eg united states lastly precipitationabundant countries for which groundwater is not as important a resource and which have predominantly rain fed agriculture do not dedicate many resources to groundwater quantity measurement resulting in a general lack of information eg see council of canadian academies overall groundwater represents a major portion of usable water resources accounting for of liquid freshwater unesco groundwater reserves are estimated to be over million km of which is freshwater