A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand.

Thesis (M.Eng.) - Asian Institute of Technology, 1975

A theoretical study of hydraulic model for steady non-uniform flow was carried out in this research. The study was restricted to straight channel only of rectangular and trapezoidal or nearly trapezoidal cross-section. The study revealed that un-distorted scale (br dr ) model for non-uniform flow at a design discharge (Q) can be simulated the proto-type but with a distorted scale (b J d ) model the to results are erroneous. To overcome this unsafe situation situation two methods have been suggested; use a model with composite roughness (n ,nb ), or adjust the results with correction factor. These s ,m ,m two methods are found to be valid also for the case of discharge (Qry other than design discharge (Q). The study also considered the case of uniform flow at other discharges and it was observed that with a distorted scale model, the same problem arises as in the case of non-uniform flow. This situation can also be improved with the above two methods. However, it was noticed that model for channel of exponential cross-section is not affected by the distortion of scale under any kind of flow, uniform or non-uniform, and at any discharges (Q or Q'). To varify the theoritical consideration many numerical examples have been considered and a limited laboratory experiment was carried out.