To McCaffrey, the fundamental characteristic of groundwater seemed to be that while its flow is slow in comparison with that of surface water, it is constantly in motion, and while it may in exceptional cases exist in areas where there is virtually no surface water, it is normally closely associated with rivers and lakes.
فالمياه الجوفية يعول عليها تعويلا شديدا لتلبية الاحتياجات البشرية الأساسية في العالم النامي.