Practical Channel Hydraulics Practical Channel Hydraulics Roughness, Conveyance and Afflux Donald W. Knight The University of Birmingham, Birmingham, UK Caroline Mc Gahey HR Wallingford, Wallingford, Oxfordshire, UK Rob Lamb JBA Consulting, Skipton, North Yorkshire, UK Paul G. Samuels HR Wallingford, Wallingford, Oxfordshire, UK CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business © 2010 Taylor & Francis Group, London, UK Typeset by Vikatan Publishing Solutions (P) Ltd, Chennai, India. Printed and bound in Great Britain by TJ International Ltd, Padstow, Cornwall All rights reserved. No part of this publication or the information contained herein may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publisher. Although all care is taken to ensure integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers nor the authors for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein. Published by: CRC Press/Balkema P.O. Box 447, 2300 AK Leiden, The Netherlands e-mail:
[email protected] www.crcpress.com – www.taylorandfrancis.co.uk – www.balkema.nl Library of Congress Cataloging-in-Publication Data Knight, Donald W. Practical channel hydraulics : roughness, conveyance, and afflux / Donald W. Knight . . . [et al.] p. cm. Includes bibliographical references and indexes. ISBN 978-0-415-54974-5 (hardcover : alk. paper) – ISBN 978-0-203-86418-0 (e-book) 1. Channels (Hydraulic engineering) I. Title. TC175.K55 2010 627’.042–dc22 2009026759 ISBN: 978-0-415-54974-5 (Hbk) ISBN: 978-0-203-86418-0 (eBook) Contents Foreword Acknowledgements Notation Acronyms Glossary of terms 1 2 xi xiii xv xxi xxiii Introduction 1 1.1 Context and motivation for book 1 1.2 Scope of book and introduction to the CES-AES 6 1.3 Limitations of the CES-AES 7 1.4 Outline of book 8 1.5 Origin of the CES-AES 9 Practical and theoretical issues in channel hydraulics 2.1 2.2 15 Getting started with some practical examples on calculating flows in watercourses 15 Common difficulties in modelling flow in rivers and watercourses 24 2.2.1 Modelling flow in rivers and watercourses 25 2.2.2 Schematisation of channel geometry 26 2.2.3 Roughness and resistance 29 vi Contents 2.3 Energy and friction slopes 33 2.2.5 Velocity distributions and implications for 1-D modelling 37 2.2.6 Hydraulic structures and controls 42 2.2.7 Calibration data for river models 44 Flow in simple engineered channels 45 2.3.1 Flows in rectangular channels 50 2.3.2 Flows in trapezoidal channels 54 2.4 Inbank flow in natural rivers 57 2.5 Overbank flow in natural and engineered rivers 59 2.5.1 Overbank flow in an engineered river 60 2.5.2 Overbank flow in a natural river 64 2.6 2.7 3 2.2.4 Flows through bridges and culverts 69 2.6.1 Flows through bridges and contractions