Traditional concepts of aquifers and watersheds do not link faulting and related fracture zones with country or regional water balances. This misperception of the interaction of local and regional surface and groundwater hydrologies has severely constrained growth planning in arid countries. It is becoming increasingly evident that a realistic depiction is a prerequisite for integrated resource management. Recent advances in the technology of groundwater exploration have led to a revision of conventional definitions of aquifers and basin water balances, especially in arid regions. Modern, interdisciplinary teams of technologists and scientists, using space-age remote sensing combined with advanced geophysical, geological and geographic information system (GIS) mapping techniques, are discovering accessible, useable, fresh, brackish and hydrothermal groundwaters in regions where traditional methods failed to detect the resources. At the same time, major progress in the development of low-cost desalination technologies has opened the possibility that newly identified, naturally recharged reservoirs of brackish and thermal groundwater can be economically developed and treated for beneficial use. State-of-the-art groundwater exploration and desalination technologies can now be fully integrated with socioeconomic and environmental databases using GIS to map, test, develop and effectively manage multi-source water resources on a regional scale. This combination of space-age technologies offers an unprecedented opportunity for near-term economical development of significant quantities of renewable groundwater in arid areas.