Hydrologic History, Problems, and Perspectives

Abstract Since humans first settled along the banks of lakes and rivers, there has been a keen interest in the proper management of fresh water resources both as a necessity for life as well as to avoid potential health hazards. Along the Indus in Pakistan, the Tigris and Euphrates in Mesopotamia, the Hwang Ho in China, and the Nile in Egypt, the first “hydraulic engineers” created canals, levees, dams, subsurface water conduits, and wells as early as 5000–6000 years ago. Hydrologic information became vital to these early civilizations. The flow rates and yields of rivers were monitored by the Egyptians as early as 3800 years ago, and rainfall measuring instruments were first used approximately 2400 years ago by Kautilya of India. The idea that a global hydrologic cycle actually exists dates back at least 3000 years when early Greek philosophers such as Thales, Anaxagoras, Herodotus, Hippocrates, Plato, and Aristotle conceptualized the basic ideas governing the process. Many initial ideas established by the Greeks about the hydrologic cycle were quite reasonable. However, many of the initial mechanisms concerning the routes by which water returned from the sea and entered rivers were devoid of as much logic. Despite apparent gaps in hydrologic mechanisms, the Romans developed aqueduct systems reflecting an extensive practical understanding of hydrology and hydraulics and did so using the basic hydrologic ideas established and passed along by the Greeks.