**Abstract**

Before any major hydraulic engineering project is undertaken for planning, designing, construction, or revamping and rehabilitation some kind of model study is but a necessity. Depending upon the time, resources and, significance of the project, the study could be done only on the paper and computer screen using some graphical, analytical or, statistical software and tools, or it could be combined with the more expensive and time consuming physical model study also. This chapter focuses on the question as to why the physical modeling should be reintroduced into engineering practice because of the modern techniques and systems now available for construction, operation and, data analysis of these physical models.

**Keywords:** hydraulic modeling, physical modeling, hydrological modeling, model, prototype, similitude, hydraulic research, Nandipur, barrage, weir, spillway, water resources
