This book provides comprehensive insights into the field of hydrology. It traces the evolution of this field and talks in detail about its importance in the present day scenario. Hydrology refers to the study of quality, distribution and movement of water and water bodies on earth and other planets. It is also concerned with the study of environmental watershed sustainability, water resources and hydrologic cycle. It is used in the fields like geology, environmental engineering, environmental sciences, civil engineering and physical geography. This book is a valuable compilation of topics, ranging from the basic to the most complex theories and principles in the field of engineering hydrology. Also included in it is a detailed explanation of the various concepts and applications of this subject. It aims to serve as a resource guide for students and experts alike and contribute to the growth of the discipline.