Hydrology is the discipline that focuses on the scientific study of water present on Earth or other planets. It includes the movement, quality and distribution of water on the planets including water resources, water cycle and environmental watershed sustainability. It focuses on analyzing water related problems such as water management, natural disasters, environmental preservation and provide their solutions. Hydrology is sub-divided into groundwater hydrology, surface water hydrology and marine water hydrology. Surface hydrology, hydrometeorology, hydrogeology, drainage basin management and water quality are some of the other domains of hydrology. Water circulation or water cycle is the central aspect of hydrology. It is concerned with how water circulates across the Earth through various pathways. This book unravels the recent studies in the field of hydrology. Different approaches, evaluations, methodologies and advanced studies have been included herein. Those in search of information to further their knowledge will be assisted by this book.