الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The effects of rigid ditch bank weeds/ vegetation on the flow parameters and
the bed morphology were investigated. One hundred sixty-eight tests were
conducted to study the impacts of different vegetation densities. Tests were
run for three vegetation densities (1600, 400, and 178 stems/m2) along a fixed
4.00 m reach, against four different discharges, each with three different
depths. The measured water levels, velocities and scour depths along the
vegetated reach were analyzed. It was found that the existence of bank
vegetation increased the water depth upstream of the vegetated reach and
lowered it within the vegetated reach, when compared to the unvegetated case.
The water’s velocity profile as a ratio to the unvegetated case (V/u) is sigmoid,
i.e., the maximum velocity (V/u) max occurs in the lower half of the water
column, increasing shear stress near the bed, and, in turn, the likelihood of
bed erosion along the vegetated channel’s centerline. V/u increased with
increasing vegetation density and Fro. Also, it is remarkable that the presence
of bank vegetation increases scour around the center of the vegetated reach
and reduces it near the vegetated bank. The change in both water level,
velocity and scour depth is a function of vegetation density and channel
geometry (Fr). Finally, a multiple regression analysis was done to assess the
impact of ditch bank vegetation density on flow parameters and the canal’s
bed morphology. Fourteen empirical equations were deduced to estimate the
change in flow parameters and bed level due to ditch bank vegetationto ditch bank vegetation.