Return to HydroWeb HomepageISSN 1058-3912
Electronic journal of the International Association
for Environmental Hydrology
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JEH Volume 8 (2000), Paper 14, October 2000
Posted October 20, 2000
RESPONSE THEORY FOR ALLUVIAL RIVER ADJUSTMENTS TO ENVIRONMENTAL AND
MAN-MADE CHANGES
Youssef I. Hafez
Nile Research Institute Water Research Center, DeltaBarrage
El Kanater, Greater Cairo, Egypt
ABSTRACT
A response theory is developed for prediction of the direction and
magnitude of alluvial river adjustments from one regime to another due
to environmental and man-made changes. The theory makes use of the tendency
of alluvial channels toward dynamic equilibrium after being disturbed by
an extreme event. Various extremal concepts are adopted such as energy
dissipation (including its special cases of stream power, unit stream power
and energy slope), sediment efficiency, friction factor and Froude number.
The regime theory hydraulic exponents, which are usually taken as constants,
are derived in a more general fashion where the classical reported values
could be obtained. After selecting the function that describes each concept
and setting its variation to zero, a equation that represents the response
of the river channel is obtained. This response is given in the form of
a relation between adjustments or variations between the width, depth,
slope, discharge, and channel roughness. Comparisons with field data for
ten cases of river response show the success and potential of this approach.
Reference: Hafez, Y.I.; Response Theory for Alluvial River
Adjustments to Environmental and Man-made Changes, Journal of Environmental
Hydrology, Vol. 8, Paper 14, October 2000.
Youssef Hafez
Nile Research Institute
National Water Research Center Delta Barrage
El Kanater
Greater Cairo
13621 Egypt
E-mail: youssef_hafez@usa.net