Variation in hydraulic geometry for stable versus incised streams in the Yazoo River basin – USA

Abstract

The effects of basin hydrology on hydraulic geometry of channels variability for incised streams were investigated using available field data sets and models of watershed hydrology and channel hydraulics for the Yazoo River basin, USA. The study presents the hydraulic geometry relations of bankfull discharge, channel width, mean depth, cross-sectional area, longitudinal slope, unit stream power, and mean velocity at bankfull discharge as a function of drainage area using simple linear regression. The hydraulic geometry relations were developed for 61 streams, 20 of them are classified as channel evolution model (CEM) Types IV and V and 41 of them are CEM streams Types II and III. These relationships are invaluable to hydraulic and water resources engineers, hydrologists, and geomorphologists involved in stream restoration and protection. These relations can be used to assist in field identification of bankfull stage and stream dimension in un-gauged watersheds as well as estimation of the comparative stability of a stream channel. A set of hydraulic geometry relations are presented in this study, these empirical relations describe physical correlations for stable and incised channels. Cross-sectional area, which combines the effects of channel width and mean channel depth, was found to be highly responsive to changes in drainage area and bankfull discharge. Analyses of cross-sectional area, channel width, mean channel depth, and mean velocity in conjunction with changes in drainage area and bankfull discharge indicated that the channel width is much more responsive to changes in both drainage area and bankfull discharge than are mean channel depth or mean velocity.