"Hydrology remains a hybrid between the art and the science," wrote Robert L Smith in 1990
“Good practice of the art is dependent on understanding the theory of the science; not the reverse. Become fundamentally sound in the theory, and your ability to accept and adjust for uncertainty in boundary conditions will reflect good judgement. Hydrology remains one of the few opportunities in technology where one’s diagnostic capability is put to the test of both theory and experience,” stated Robert L Smith in 1990.