الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
Existence of weeds in irrigation channels causes many senous
problems such as velocity reduction, increase in water levels, and prevents
water from reaching the canal end. So aquatic weeds have to be controlled to
an acceptable level to improve the channels performance. The main objective
of the study is how to adapt irrigation channels with the used irrigation
systems in the presence of weeds as unacceptable phenomenon difficult
healing. Hence the urgent need for harmonization between the presence of
weeds of acceptable densities and to maintain water levels in the last reaches of the channels, which are mainly infested by the weeds. So this study aims to achieve the following goals:
- Study the impact of the existence of weeds (submerged and floating)
on the roughness coefficient in case of maintaining the water levels behind the
infested areas.
- Study the impact on the water line upstream the infested areas in the case of maintaining the water levels at the last reach.
- Determine the densities of weeds affecting the flow, which lead to the lifting of the water surface and various lifting rates to determine the densities that can coexist with it.
- Study the energy loss through infested areas and determine the relationship between losses in the energy and density of weeds.
- Determine the impact on the shear velocity in presence of weeds to
determine the critical shear velocity that may lead to erosion and
sedimentation in irrigation channels.
- Study the impact on the style and flow behavior in different sections 111
presence of weeds.