The object of this study was to investigate the hydraulic behavior of spatially varied flow with decreasing discharge and to check the suitability of theoretical dynamic equations of water surface profile developed from both momentum principle and energy principle. Method of analyses used in this paper included: (1) experimental study and (2) numerical investigation. Experimental work was conducted in a rectangular flume with width x depth = 5” x 8”, and 10 feet long. A side weir was fixed at the middle of the flume with height equal to 2”. Overflow discharge was caught in a flume 12” x 12” in cross-section, and 5.5 feet long. Water profiles in both cases of supercritical flow and supercritical flow were measured so as to compare with theoretical profiles. Numerical investigation was facilitated by using 7040 digital computer. Actual measured profiles were compared with theoretical profiles. From the observation of the results it was concluded that the energy principle was suitable in the development of dynamic equation. / M.S.