Fundamental principle of International Water Law which entitles a international watercourse and/ or an aquifer State to an equitable and reasonable share of the uses and benefits of a watercourse and/ or an aquifer and creating the correlative obligation not to deprive other international watercourse and/ or aquifer States Fundamental principle of International Water Law which entitles a international watercourse and/ or an aquifer State to an equitable and reasonable share of the uses and benefits of a watercourse and/ or an aquifer and creating the correlative obligation not to deprive other international watercourse and/ or aquifer States