Parsimonious Mathematical Characterization of Channel Shape and Size

Abstract

This work has two purposes: (1) starting from the classic hydraulic geometry formulation, present a mathematically parsimonious, two-parameter, characterization of channel shape and size; and (2) analytically quantify cross-sectional area, top width, average depth, critical energy, and bank-full discharge at critical conditions as a function of these two parameters. The matter of channel asymmetry is examined, and a metric for quantifying asymmetry is presented. The robustness of this characterization is demonstrated in an application to several observed channels in Maryland and Delaware across three physiographic regions: Allegheny plateau, Piedmont, and coastal plain. Values of the shape parameter, u, ranged from 1.6 to 4.3, and asymmetry measures ranged from 0.09 to 0.51 for the demonstration cross sections. The channel characterization and set of channel property relationships have value for both analysis and design applications related to stream restoration, in which the consistency of a designed channel with existing field conditions is imperative for channel stability.