Taer scarcity refers to the volumetric abundance or lack thereof,of water supply.this is typically calculated as a ratio of human water consumption to available water supply in a given area.water scarcity is a physical ,objective reality thta can be measure consistently across regions and ver time

water stress
water stress refers to the ability or lack of thereof,to meet human and ecological demand for water.compared to scarcity "water stress" is a more inclusive and broader considers several physical aspects related too water resources