HR: 14:35h
AN: H33J-04    [Abstracts]
TI: Geometric Scaling of Step-pool Channels
AU: * Chartrand, S M
EM: schartrand@balancehydro.com
AF: Balance Hydrologics, Inc., 841 Folger Avenue, Berkeley, CA 94710-2800,
AU: Whiting, P J
EM: peter.whiting@case.edu
AF: Case Western Reserve University, Department of Geological Sciences 112 A.W. Smith Bldg. 10900 Euclid Avenue, Cleveland, OH 44106-7216,
AU: Stamm, J F
EM: jstamm@balancehydro.com
AF: Balance Hydrologics, Inc., 841 Folger Avenue, Berkeley, CA 94710-2800,
AB: Step-pool channels are a ubiquitous element of mountain watersheds. As communities continue to expand into the mountainous regions of the world, an increased understanding of step-pool properties and characteristics is essential to support informed land-use decisions. A surge in recent research has explored fundamental characteristics of step-pools in part from the perspective of utilizing step-pools in stream restoration or stabilization efforts. Much of this research has focused on applying hydraulic and energy theory to elucidate controls on step-pool geometry. These approaches are based on the concept that step-pool form evolves to provide a maximum resistance to flow. We describe a new perspective on step-pool geometric scaling. Our work suggests that step-pool geometry is the result of interactions between channel geometry and step-pool hydraulics, notably head loss through the step-pool reach. We will illustrate that at the reach level of organization, the ratio of bankfull width to head loss can be described by average reach slope. Step-pool wavelength and height are in turn well described by bankfull width, again expressed as ratio to head loss through the step-pool reach. These results provide for a fundamental understanding of step-pool form in relation to watershed-scale systems. Our results also suggest that average head loss and bankfull width through a step-pool reach are perhaps the most important scaling variables of step-pool geometry. The existing literature has thus far failed to consistently demonstrate a linkage between geometry and reach-average slope. Our work has been tested against data from other existing studies and reveals that data from different physiographic regions of the Western U.S. and within different climatic zones agree well with our data. Because we use data from naturally developed step-pool reaches across a spectrum of geologies and climates, our results are applicable for use with channel evolution models and perhaps more importantly in the design of engineered step-pool reaches. We compare engineered step-pool geometry to our data.
DE: 1825 Geomorphology: fluvial (1625)
DE: 1856 River channels (0483, 0744)
SC: Hydrology [H]
MN: 2007 Fall Meeting