Scholarly Communications Project


DETERMINATION OF OPTIMAL STABLE CHANNEL PROFILES

by

GREGORIO G. VIGILAR, JR.

Dissertation submitted to the Faculty of the Virginia Tech in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY

in

CIVIL ENGINEERING

Approved

PANAYIOTIS DIPLAS, Chair
DAVID KIBLER
STERGIOS LIAPIS
SAAD RAGAB
MARK WIDDOWSON

JANUARY 28, 1997
Blacksburg, Virginia


Abstract

A numerical model which determines the geometry of a threshold channel was recently developed. Such a model is an important tool for designing unlined irrigation canals and channelization schemes, and is useful when considering flow regulation. However, its applicability is limited in that its continuously curving boundary does not allow for sediment transport, which is an essential feature of natural rivers and streams. That model has thus been modified to predict the shape and stress distribution of an optimal stable channel; a channel with a flat-bed region over which bedload transport occurs, and curving bank regions composed of particles that are all in a state of incipient motion. It is the combination of this channel geometry and the phenomenon of momentum-diffusion, that allows the present model to simulate the Œstable bank, mobile bedı condition observed in rivers. The coupled equations of momentum-diffusion and force-balance are solved over the bank region to determine the shape of the channel banks (the bank solution). The width of the channelıs flat-bed region is determined by solving the momentum-diffusion equation over the flat-bed region (the bed solution), using conditions at the junction of the flat-bed and bank regions that ensure match ing of the bed and bank solutions. The model was tested against available experimental and field data, and was found to adequately predict the bank shape and significant dimensions of stable channels. To make the model results more amenable to the practic ing engineer, design equations and plots were developed. These can be used as an alternative solution for stable channel design; relieving the practitioner of the need to run the numerical program. The case of a stable channel that transports both bedload and suspended sediment is briefly discussed. Governing equations and a possible solution scheme for this type of channel are suggested; laying the groundwork for the development of an appropriate numerical model.


List of attached files

File NameSize (Bytes)
Abstract.pdf7,872 Bytes
Appndxa.pdf34,641 Bytes
Appndxb.pdf33,724 Bytes
Appndxc.pdf32,395 Bytes
Appndxd.pdf17,684 Bytes
Chap1.pdf9,838 Bytes
Chap2.pdf51,752 Bytes
Chap3.pdf48,113 Bytes
Chap4.pdf30,916 Bytes
Chap5a.pdf129,683 Bytes
Chap5b.pdf120,499 Bytes
Chap5c.pdf94,483 Bytes
Chap6.pdf39,702 Bytes
Chap7.pdf17,416 Bytes
Etd.pdf5,777 Bytes
Frontmtr.pdf51,350 Bytes
Refrnces.pdf15,954 Bytes
Vita.pdf7,841 Bytes
etd.pdf5,777 Bytes


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