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Biswas B., das B. C., 2016. Hydraulic parameters and morphometric variables interactions in bedrock channel. Quaestiones Geographicae 35(3), Bogucki Wydawnictwo Naukowe, Poznań, pp. 75-88, 12 figs.aBstraCt: Present study is on the interdependent nature of hydraulic parameters and morphometric variables of a bedrock river. In this study, using dumpy level, GPS, satellite images and some mathematical equations a data set on hydraulics and morphometric variables of a bedrock channel, named Bhatajhor, of eastern India was generated. That data set was used to (1) find out impulse-response relations between hydraulic variables (2) find out relations between morphometric variables and (3) find out relations between hydraulic and morphometric variables. Seven equations (5-11) were formulated based on this empirical study to the end. The seven empirical relations, most of which include only two variables, involve channel cross-section dimensions (area, width, mean depth, maximum depth, width/ depth ratio, hydraulic radius), slope and hydraulic variables (velocity, kinetic energy, stream power, Manning's n factor, Chezy's C factor and shear stress). Observation shows relatively higher coefficient of determination (R2) between variables like velocity and Manning's n factor (0.67), velocity and Chezy's C factor (0.67), slope and τ (0.89), w/d ratio and hydraulic radius (0.53), slope and w/d ratio (0.50).

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A fundamental index of channel shape is the form ratio (w/d) which is determined by energy-load relation and bank and bed materials of the channel concerned. Average river channels tend to develop their channel-cross sectional form in a way to produce an approximate equilibrium between the channel and the water and sediment it transport. But how far it is deviated from the ideal cross-sectional form is determined only by knowing the ideal form which was calculated '2' by Hickin (2004) for rectangular channel. This ideal cross-sectional form of 'maximum efficiency' is virtually a theoretical one and by attaining of which a river transports its water and load with least friction with its bed. But ideal form ratios for triangular and semicircular channels have not been calculated earlier. Present paper has found out ideal form ratios 2.544 and 2.31 for semicircular and triangular channels respectively.