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Aggradation in Mobile Boundary Channel Due to Overloading of Sediments

Author(s): P. Laxmi Narayana; P. V. Timbadiya; P. L. Patel

Linked Author(s): Prafulkumar V Timbadiya, Prem Lal Patel

Keywords: Ggradation; Bedforms; Ultrasonic ranging system; Analytical model

Abstract: Excess sediment deposition in the channel is characteristic of aggrading streams. Often, the cause of aggradation is an increase in upstream sediment load and hence exceeding the transport capacity of the channel. It is important to study the effect of overloading in streams, as many streams are so delicately balanced, and, any natural or artificial changes like landslides or throwing of mining wastes in the river bed, effect the morphology of streams. Researchers, in past, worked to determine the aggradation in a channel by developing the linear and non-linear parabolic models. It is important to evaluate the performance of existing models, so that these models can be used in the field with appropriate field conditions. The present study aims to experimentally investigate the effect of overloading on riverbed evolution under stipulated hydraulic conditions by using the model developed by (Soni et al., 1980). Aggradation experiments were carried in a 15 m long recirculating flume having width 0.89 m and depth of 0.6 m (Patel et al., 2015). Space-time dynamics of the bed evolution are studied by using 5 MHz Ultrasonic Ranging System (URS) in working section of 6 m long which is 4 m away from the upstream section of the flume by overloading the sediments to a movable bed channel previously maintained under equilibrium. The sand forming the bed and injected material had a median diameter of 0.758) 8) 8) 8) and Standard deviation, 2) 2) =1.27. The analytical model developed by stipulated hydraulic conditionshas been validated from the experimental results. The results showed satisfactory agreement with corresponding developed analytical model.


Year: 2016

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