Groundwater development has shown phenomenal progress during past few decades. There has been a vast improvement in the perception, outlook and significance of groundwater resource. The unplanned groundwater development may result in fall of water levels, failure of wells, and salinity ingress in coastal areas. The development and over-exploitation of groundwater resources in many parts of the world have raised the concern and need for judicious and scientific resource management and conservation. This book "Groundwater Assessment and Modelling" is intended to provide a comprehensive treatise on assessment and modelling of groundwater. It presents the related aspects on assessment of groundwater potential, groundwater data requirement and analysis, basic concepts and guidelines for groundwater modelling, groundwater modelling software, modelling of unsaturated flow, modelling of sea water intrusion, and impact of climate change on groundwater resources. The book is expected to be quite useful for undergraduate and postgraduate students (water resources engineering), field engineers and researchers working in the area of assessment, development and management of groundwater resources. Chapters: 1. Water Resources of India 2. Water Balance Analysis 3. Overview of Groundwater Hydrology Aspects 4. Management of Aquifer Recharge 5. Assessment of Groundwater Potential 6. Groundwater Data Requirement and Analysis 7. Introduction to Groundwater Modelling 8. Basic Concepts for Groundwater Modelling 9. Conceptualisation and Model Design 10. Guidelines for Groundwater Modelling 11. Data Requirements for Groundwater Modelling 12. Capabilities of Groundwater Modelling Software 13. Overview of Groundwater Models 14. A Modular Three-Dimensional Groundwater Model (MODFLOW) 15. Pitfalls and Sensitivities in Groundwater Modelling 16. Common Groundwater Modelling Errors 17. Modelling of Unsaturated Flow 18. Hydrological Problems in Coastal Areas 19. Modelling of Sea Water Intrusion with SUTRA 20. Challenges in Numerical Modelling of Salt Water Intrusion 21. Impact of Climate Change on Groundwater Resources 22. Mathematical Modelling: Case Studies