DEFINITION AND SCOPE
Hydrology is literally the science of water. Etymologically, the word has its roots in ancient Greek, and is a composite, made up of ὕδωρ, water, and λόγος, word. Obviously, defined this way, the term is much too broad to be very useful, as it would have ramifications in all scientific disciplines.
Actually, the word hydrology has not always been well defined and even as recently as the 1960s it was not very clear exactly what hydrology was supposed to cover and encompass. Price and Heindl (1968), in a survey of many of the definitions that had appeared in the literature over the previous 100 years, were compelled to conclude that the question “What is Hydrology?” had not been resolved by their review. Still, they felt that, in general, there seemed to be a consensus that hydrology is a physical science, which is concerned mainly with the water cycle of land and near-shore areas; moreover, there had been a tendency to broaden the term rather than to narrow it, even to the point of including socio-economic aspects.
Over the past few decades, however, with the growing activity level and the increasing maturity of this field of endeavor, a more precise definition has emerged.