The at‐a‐station hydraulic geometry of stream channels that are in quasi‐equilibrium has been associated with the minimum variance concept. In this study, minimum variance is viewed as a particular approach to implementing a more fundamental idea, that of equable change in at‐a‐station hydraulic geometry in response to change in discharge. An alternative approach to characterizing equable change is formulated in terms of variables transformed tozscores. The hypothesis of equable change is tested by imposing a restriction of equal exponents on a system of hydraulic geometry equations formulated in terms of these variables. This is equivalent to testing the hypothesis that the correlations between hydraulic geometry variables and discharge are all equal. The hydraulic geometry of 35 of 61 sites analyzed is consistent with the equable change principle, implying that these channels are in a quasi‐equilibrium state. Constraints on width adjustment or velocity adjustment appear to operate in a large number of the remaining sites. Channels that are consistent with the equable change principle are compared across a number of characteristics with channels that manifest width and velocity constraints, in order to gain insight into the nature of these
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