A Continuously Varying Parameter Model of Downstream Hydraulic Geometry

Few studies have attempted to examine explicitly the factors that produce variation in hydraulic geometry parameters. A continuously varying parameter model of downstream hydraulic geometry is formulated to address this issue. Parameter variation is viewed as a function of channel sediment characteristics and flood magnitude. Results for the Missouri River basin show that these factors are strongly associated with variation in hydraulic geometry coefficients and exponents. The results also indicate that bivariate relationships are biased by these associations. The analysis yields site‐specific parameters that uniquely describe the relationship between active channel form and mean discharge at a particular location within the basin. The continuously varying parameter approach has several advantages: (1) it isolates the separate influences of each explanatory variable on each hydraulic geometry parameter, (2) it maintains the precision of parameter estimates by including the entire data set in the analysis, and (3) it allows testing of the conception that hydraulic geometry parameters vary continuously rather than discretely, yet permits analysis of discrete change through the use of dummy variables.