This book takes a non mathematical looks at the principles and processes of hydrology. Now in its fourth edition, this well established book preserves the essential structure, clarity and style which have ensured its continued international popularity over more than three decades. However the book has been revised and fully updated to take into account new research and developments in the subject and the changing role of hydrology in the modern world. The thematic treatment of the main phases of the hydrological cycle i.e. precipitation, interception, evaporation, subsurface water and stream flow, has been retained, together with the chapter on water quality. A final, synthesising chapter has been reinstated by popular demand, together with a broader spectrum of case studies and examples. A selection of problems and exercises has also been included at the end of each chapter.