Water is an important element for life on the earth. It is an essential natural resource for environmental sustenance. In India, water quality modeling studies are carried out from fresh water to marine water ecosystems. Some of the examples are Tehri reservoir, Chilka lake, Oatcake at Kashmir, Kodaikanal lake, Ooty lake at Tamil Nadu, rivers like Ganges, Narmada, Kaveri, and coastal regions like Hoogly estuary, Paradip, Vishakhapatnam, Kakinada, Chennai, Mangalore coast, Konkan coast and Gujarat coast. Water quality modeling plays a vital role in water quality studies. Numerical models are to be successfully calibrated and properly applied and it is to be improved our understanding of the complex interactions among different parameters such as temperature, biological oxygen demand, dissolved oxygen, salinity, and eutrophication in the fresh water and sea water environment.

R. Manivanan: Senior Researcher, Centre for Water and Power Research Institute (CSIR) Pune, Maharashtra, India

1. Introduction 2. Water Quality Modeling: Basics 3. Modeling: Processes and Development 4. Modeling: Applications 5. Modeling: Methodologies 6. Modeling: Rivers and Streams 7. Modeling: Coastal and Estuaries 8. Modeling: Lakes and Reservoirs 9. Modeling: Oceans and seas 10. Water Quality Modeling: BOD and DO 11. Salinity and Temperature Modeling 12. Nitrogen and Phosphorus Modeling 13. Eutrophication Modeling 14. Oil Spill Modeling 15. Tsunami Modeling 16. Littoral Drift modeling 17. An Ecohydrology Model 18. Commercially Available Models