Intake canals are used to withdraw water from rivers for various purposes. Sedimentation in the intake canal reduces the quality and quantity of water being delivered. In this study, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°. The variables in the study included vane angle, number of vane rows, and vane spacing in terms of mean flow depth in the main channel. In addition to the commonly used vane array with uniform vane heights, three other vane-height configurations were also tested. The least local scour around vanes and highest sediment reduction (~70%) were observed for vanes oriented at a 15° vane angle with an increasing vane-height configuration placed in two rows. It was also observed that control of sediment entry into the intake canal increased with an increase of both vane spacing and number of vane rows. © 2018 American Society of Civil Engineers.

Venu Chandra

Department Of Civil Engineering

Sruthi Thazhathe Kalathil

Flow patterns

Hydraulic structures

Sediments

local scour

Mean flow

MOBILE BED

physical model

SECONDARY CIRCULATION

SEDIMENT REDUCTION

SUBMERGED VANES

VANE HEIGHT

Canals

canal

Inflow

sediment

Sedimentation

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Control of sediment inflow into a trapezoidal intake canal using submerged vanes

Journal of Waterway, Port, Coastal and Ocean Engineering

River confluences have complex hydrodynamics than ambient flows due to different flow characteristics of the two merging flows. Secondary circulation develops due to merging of two flows which leads to bed erosion. The eroded sediment gets deposited at various locations in the downstream of the confluence. It is reported in the literature that major reservoirs in India will lose 50% storage capacity by 2020 and reservoirs all over the world lose storage capacity by as much as 5% every year. In view of controlling bed erosion at the confluence, vane and circular pile models are used as scour mitigation structures and experimental results are presented. Experiments are performed in a distorted model with a non-uniform sediment of mean particle size d50 = 0.28 mm with a confluence angle of 60°. Two different discharge ratios (Qr= ratio of lateral flow discharge to main flow discharge) of 0.5 and 0.75 are used with a constant flow depth (Hm) of 5 cm in the main channel. Vanes of width 0.3Hm (1.5 cm), thickness of 1 mm are placed at 15°, 30° and 60° vane angles with respect to main flow. Circular pile models of 8 and 12 mm diameter are also used. Two different spacing of 2Hm and 3Hm (10 and 15 cm) between the vanes or piles are used to perform the experiments. For Qr= 0.5 and 0.75 using vanes, scour depth reduces by 25 and 34%, respectively. When circular pile models of 8 and 12 mm are used, the scour depth reduces by 25, 38 and 27, 43%, for Qr= 0.5 and 0.75, respectively. The scour depth decreases with an increase of vane angle and pile diameter, but increases with an increase of spacing. Therefore, piles have better performance over vanes in reducing scour at the confluence. © 2017, Iran University of Science and Technology.

International Journal of Civil Engineering

Control of Bed Erosion at 60° River Confluence Using Vanes and Piles

Confluence is a common occurrence in rivers. The convergence of flows often leads to erosion of the river bed and formation of a deep scour-hole at the confluence. In the present experimental study, vanes and circular piles are proposed as scour mitigation measures. Experiments are performed in a distorted mobile bed model (d50 = 0.28 mm) with 90° confluence angle. Three different discharge ratios (Qr = ratio of lateral to main flow discharge) of 0.33, 0.50 and 0.75 are used. Vanes (1.5 cm width and 1 mm thick) or piles (ɸ = 8 mm and 12 mm) are arranged in a row perpendicular to the lateral flow at a spacing of 5, 10 or 15 cm. Three vane angles of 15°, 30° and 60° with respect to the main flow are used. The experimental results show that scour depth (Sd) increases with an increase of Qr. Sd reduces by 33%, 50% and 47% with vanes for Qr = 0.33, 0.50 and 0.75, respectively. Sd reduces by 43%, 55% and 55% with 12 mm piles and by 70%, 60% and 59% with 8 mm piles, for the corresponding discharge ratios. It is observed that Sd increases with an increase of vane angle and pile diameter, but it decreases with an increase of spacing. The performance of circular piles is better than vanes in controlling bed erosion. © 2017 International Association for Hydro-Environment Engineering and Research.

International Journal of River Basin Management

Methods to control bed erosion at 90° river confluence: an experimental study

Hydraulic Modelling – an Introduction

Journal of Waterway, Port, Coastal, and Ocean Engineering

Reviewers

Irrigation & Drainage Systems Engineering

Mitigation of Sedimentation at the Diverstion Intake of Fota Spate Irrigation: Case Study of the Gash Spate Irrigation Scheme, Sudan

Journal	Data powered by TypesetJournal of Waterway, Port, Coastal and Ocean Engineering
Publisher	Data powered by TypesetAmerican Society of Civil Engineers (ASCE)
ISSN	0733950X
Open Access	No