Disaster & Development Journal of the National Institute of Disaster Management Volume 3 O Number 1 O April 2009 Special Issue: Urban Floods-I ©National Institute of Disaster Management (NIDM), New Delhi. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system without permission from National Institute of Disaster Management (NIDM), New Delhi. ISSN: 0973-6700 Disaster & Development Journal is published two times a year and is distributed by KW Publishers Pvt Ltd. www.kwpublishers.com Published in India by Kalpana Shukla KW Publishers Pvt Ltd 5A/4A, Ansari Road, Daryaganj, New Delhi 110002 email: [email protected] / [email protected] Typeset by Black Innovation, New Delhi Printed and Published by Mr. P.G. Dhar Chakrabarti on behalf of National Institute of Disaster Management (NIDM), New Delhi and Printed by Glorious Printers, A-13, Jhil Mil, Delhi 110 095 and Published at NIDM, IIPA Campus, I.P. Estate, Mahatma Gandhi Marg, New Delhi 110 002. Editor: P.G. Dhar Chakrabarti Contents Volume 3 No.1 October 2009 Editorial Note vii 1. Urban Floods and Case Studies Project: An Overview 1 Anil K. Gupta and P.G.Dhar Chakrabarti 2. Urban Floods: Case Study of Delhi 15 A.K. Gosain, P.K.Khandelwal and S. Kulshrestha 3. Urban Flood: Case Study of Bhopal 47 Sanjeev Sachdeva 4. Urban Floods: Case Study of Chennai 105 T. Sundarmoorthy, L. Ramadurai and N.G. Anuthaman 5. Urban Floods: Case Study of Kolkata 183 Mohit Bhattacharya iii Disaster & Development Vol. 3 No. 1 October 2009 Contributors O Bhattacharya, Mohit (Ex-VC, University of Burdwan) Purbachal Chister-VIII, Block K-6, Salt Lake, Calcutta-700097 O Sundar moorthy, T.S. Biodiversity Conservation Division, CPR Environmental Education Centre, PPR Ayyar Foundation, Alwar pet, Channai-600018 O Sachdeva, Sanjeev, Environmental Planning & Cored nation Organisation, Paryavaran Parisar, Arera Colony, Bhopal-462016 O Khandelwal, P.K., Suptdt. Engineer, Municipal Corporation of Delhi, Delhi- 110002 O Kulshrestha, Sandeep, GIS Lab, Deptt. Of Environmental Engineering, Indian Institute of Technology, New Delhi O Gosain, A.K., Professor of Deptt. Environmental Engineering, Indian Institute of Technology, New Delhi O Ramadurai, Lalitha, CPR Environmental Education lape, Alwarpet, Chennai- 600018 O Aunthaman, N.G., CPR Environmental Education lape, Alwarpet, Chennai- 600018 O Dhar Chakrabarti, P.G., (Executive Director), National Institute of Disaster Management, New Delhi-110002 O Gupta, Anil K., National Institute of Disaster Management, New Delhi-110002 v Disaster & Development Vol. 3 No. 1 April 2009 Editorial Note One of the main challenges posed by global and local environmental changes is the In spite of step-up efforts at reducing the risks of flood, the frequency and magnitude of the floods have more than doubled in recent years. One disturbing phenomenon that is recurring on a large scale all over the world, particularly in the developing countries, is the emergence of urban flood as a major issue of disaster management. A survey of the causal factors for failure of flood control structures in mitigating urban flood, illustrated with examples from cities across the world, identified four broad categories to be very important. These are: (a) rapid unplanned urban growth with scant regard to land use and physical development regulations, (b) inadequate observation network to record and analyze hydrological and meteorological data, (c) suboptimal design and implementation of structural mitigation measures and (d) poor enforcement and governance system. A number of policy issues have emerged that concern (a) early warning of flood, b) flood modeling scenarios, (c) validity of design concepts and criteria and (d) flood regulations and management One of the main challenges posed by global and local environmental changes is the need to integrate research and assessment into decision-making processes. When dealing with issues involving uncertainty and high risks, such as natural disasters and climate change, this integration is particularly difficult but necessary. Drainage management is the key issue in urban flood risk reduction that involve the multi- sectoral issues of irrigation, flood panes, wetlands, rainwater harvesting, waste disposal, transport, slum, housing etc. Sewer and drainage systems require large investments. Investments and maintenance costs can be reduced by planning and operating the systems more efficiently and incorporating innovative solutions. Master plans with direct and indirect provisions provide opportunities for risk based land-use planning and orienting the entire urban governance system in a risk sensitive manner. Most of the Indian cities and towns are facing challenges of seasonal flood which pose serious issues for research and planning. National Institute of Disaster Management conducted a coordinated study by involving 8 city teams to capture various aspects of urban floods challenges and mitigation in the past recent past. The present issue of our journal ‘Disaster and Development’ presents four studies of the research outcome and the remaining studies shall be released in the following issue. vii Disaster & Development Vol. 3 No. 1 April 2009 Urban Floods and Case Studies Project: An Overview Anil K. Gupta and P.G.Dhar Chakrabarti Prologue Urbanization in developing countries doubled from less than 25% in 1970 to more than 50% in 2006. It is widely accepted that proactive disaster management is a necessity for maintaining the environmental integrity and economic functions of the city. Rapid and uncontrolled growth, bloom in number of vehicles, and financial constraints leading to diminishing investment of infrastructure, have worked together to make our cities highly vulnerable to known natural and un-known so-called natural disaster that are actually man-made for their origin and impacts. Flood disasters are now the most frequent and devastating natural disaster in monsoon Asia. Their impacts have grown in spite of the improved ability to monitor and assess the hazards. The expansion of urban areas into flood plains and wetlands is one reason as it places additional people and infrastructure at risk. Besides this, land-use changes have altered the run-off characteristics of watersheds. Diversions, storage dams, irrigation schemes and inter- basin transfers have altered river flows. The onset, duration, distribution, speed and quality of flood waters has already been changed by human activities. Changes in climate is further altering the flood regimes. By 2020, seven of the world’s ten largest economies will be from Asia. At the same time, Asia is one of the fastest urbanizing regions in the world. In 2000, 37% of its population lived in cities and the proportion is projected to reach more than 50% by 2025. Urbanizing societies usually spend increasing amounts to protect or rebuild damaged flood protection structures, and also respond through land-use regulations, early warning system, etc. Structural intervention to protect valuable urban-based assets, like city commerce & business, however, may shift risk of flood disasters onto other people and places. The actions during and immediately after major floods may exacerbate or limit disasters, while inappropriate recovery activities and policies can 1 Disaster & Development Vol. 3 No. 1 April 2009 Urban Floods and Case Studies Project: An Overview recreate the conditions for the next, even worse, flood disaster. Institutional capacities to manage floods and flood-related disasters are major determinants of vulnerabilities and risk of disaster. Changes in the Asian monsoon system compound the challenges of managing floods in urban regions. Urban Floods Recent phenomenon has highlighted the human-made causes that are responsible for recurring and prolonged nature of floods in South Asian cities like Dhaka, Mumbai, Chennai, Bangalore, Ahmedabad, Surat, Patna, Rawalpindi and Islamabad, etc. Flood hazards result from the overflow of land areas, temporary backwater effects in sewers and local drainage channels, creation of unsanitary conditions, deposition of materials in stream channels during flood recession, rise of ground water coincident with increased stream flow, and other problems (State of Kentucky, III-4). Mumbai is the largest and most economically important city in India, contributing annually about 17% to the nation’s income tax and 37% in corporate tax. The flood of 2005 was truly a disaster as it receded only after seven weeks and affected 20 million. The floods killed 1,200 people and 26,000 cattle. It destroyed more than 14,000 homes, damaged more than 350,000, and about 200,000 people had to stay in relief camps. The agricultural sector was heavily hit as 20,000 hectares of farmland lost the topsoil and 550,000 hectares of crops were damaged. The damage to roads and bridges was estimated at EUR 214 million. Much of the drainage system collapsed and there was a continued risk from water-borne diseases. It took several weeks before basic services were restored. Figure 1. Continued water logging in Varachha area of Surat even after eight days of flood. Disaster & Development Vol. 3 No. 1 April 2009 2 Anil K. Gupta and P.G. Dhar Chakrabarti All cities face risks from a range of natural and human-induced disasters, including disasters arising from extreme weather events, fires and industrial accidents. There can also be very