Introduction

Interest in water and related problems has grown markedly throughout all segments of society.  An understanding of the occurrences, distribution, and movement of water is essential in agriculture, forestry, botany, soil science, geography, ecology, geology, and geomorphology. In short, water is an important element of the physical environment.

We should all seek knowledge of hydrology as an aid in understanding the physical environment in which humanity has developed and in which we now live. Furthermore, the population of the world could increase by 50 percent some time this century. The majority of this global population increase of more than 3 billion people will occur in developing countries that already face shortages of potable water and food.

Questions we are often asked is why did we write a hydrology book and how does this book differ from other books? A decade ago we wrote the "Purple Book" which is the precursor of this book. It was written by an interdisciplinary team of authors who used as its foundation what we affectionately call the "Blue Book."

The Blue Book was a wonderful collection of information and analyses that was put together in the 1970s, by a group of prominent scientists and engineers, because at that time there was no text book available that was suitable for use in an introductory hydrology class. When we wrote the Purple Book there were still very few introductory hydrology books and the Blue Book was still widely used. However, the scope of Blue Book was rather narrow, the materials needed updating, and the format and style of the materials were very old fashioned.

Since publishing the Purple Book many fine hydrology books have been written and we felt that simply updating the book would not be adequate. After much thought Ward and Trimble decided to write a new text that would still include the most useful and interesting parts of both the Blue Book and Purple Book.

The main motivation for writing the new text is that we felt there were topics that needed to be included in the book and that were not adequately addressed in most hydrology books. In addition, we collectively have about 60 years of experience with a wide range of topics relating to hydrology and believe that society could benefit from the knowledge we have acquired from our mistakes and successes.

Furthermore, in the last decade society has begun to better recognize the value of using inter-disciplinary teams, and knowledge from several branches of science and engineering, to solve complex environmental and ecological problems. We have included extensive information on stream processes, sediment budgets, land use and human impacts on the hydrologic cycle, issues of concern to society, and management strategies.

Where possible we have also tried to foster an appreciation for the biology of hydrologic systems. Unlike many scientific texts every effort has been made to engage the reader in the discussion of each topic. The book contains many examples, illustrations and accounts of personal experiences.

(View PowerPoint presentation related to the Introduction and overview of the Environmental Hydrology textbook)