Book excerpt: Students are exposed to hydrology for the first time primarily through this course, and students taking the course have not had an opportunity to be exposed to hydrologic jargon before. And, in most cases this course may be the only course the students may have in hydrology in their undergraduate schooling. Therefore, this hydrology course must be at an elementary level, present basic concepts of hydrology, and develop a flavor for application of hydrology to the solution of a range of environmental problems. It is these considerations that motivated the writing of this book.