This book examines hydrological systems within the context of watershed management, focusing on the scientific processes that govern water movement, storage, and interaction across surface and subsurface environments. It explains how hydrological functions operate at the catchment scale, integrating physical, chemical, and geological factors that influence water availability and quality. The discussion addresses system responses to natural variability and human intervention, including structural controls, land use change, and policy-driven management decisions. Emphasis is placed on understanding groundwater-surface water interaction, pollutant transport, and hydrogeochemical behaviour within managed watersheds. By linking theoretical hydrology with applied assessment and learning-based approaches, the book provides a structured framework for analysing watershed systems as dynamic and interconnected environmental units. It supports critical evaluation of hydrological data, estimation of hydrogeological conditions, and informed interpretation of system perturbations in contemporary water management practice.

It is intended for students, researchers, engineers, planners, and policy professionals in hydrology, hydrogeology, and water resources management. The book serves as an academic reference and practical guide for watershed analysis, planning, and governance, supporting sustainable decision-making, regulatory understanding, and integrated management of water systems across diverse environmental and institutional contexts.