** Authors:**
KHALED ABAZA, ISSAM AL-KHATİB

** Abstract: **
Experimental testing of 5 different types of boundary shear
stress distribution in a symmetrical rectangular compound section
channel was conducted. Shear stress distributions in the main channel
and floodplains of 6 different rectangular compound cross-sections are
presented. Numerical values of regression coefficients for the
resulting 36 single-variable models representing 5 types of shear
stress for each of the 6 cross-sections have been derived. All
obtained statistics indicate that the derived regression models are
quite good, and can effectively be used to estimate shear stresses
with a high degree of reliability for constructed compound
cross-sections using relative depth as the single independent
variable. A generalized multiple-variable regression model has been
derived to predict each of the 5 experimentally measured shear
stresses as a function of 3 dimensionless parameters. These 3
dimensionless parameters combine both the depth and horizontal
dimensions of the constructed cross-sections. All obtained regression
statistics indicate the high reliability of the derived regression
model in estimating presented shear stress types in an open channel of
a rectangular compound cross-section. A single multi-variable
regression model for estimating mean shear stress at the bottom of a
rectangular compound cross-section has been formulated using average
values of obtained regression coefficients of the multiple-variable
regression model.

** Keywords: **
Open channel, Compound cross-section, Shear stress
generalization.

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