Cities and Flooding A Guide to Integrated Urban Flood Risk Management for the 21st Century

1. Cities and FloodingA Guide to Integrated Urban Flood Risk Management for the 21st Century WBI e-institute Webinar, 3 April 2012

2. Urban flooding is a serious and growing development challenge • The occurrence of floods is the most frequent among all natural disasters globally. In 2010 alone, 178 million people were affected by floods. The total losses in exceptional years such as 1998 and 2010 exceeded $40 billion. Flood events, 1970-2011 IBRD 38919 NOVEMBER 2011 WBI – Webinar, 3 April 2012

3. Rome Wasn’t Built in Day.. China Does it in Two Weeks! WBI – Webinar, 3 April 2012

4. A forward looking approach: Integrated Urban Flood Risk Management • Operational guidance on how to manage the risk of floods in a quickly transforming urban environment and changeable climate. • Over fifty case studies, a series of “how-to” sections and a set of guiding policy principles, illustrate the state-of-the art on integrated urban flood risk management. • Comprehensive and user-friendly, the Guide serves as a primer for decision and policy makers, technical specialists, central, regional and local government officials, and concerned stakeholders in the community sector, civil society and non-governmental organizations, and the private sector. • Website: http://www.gfdrr.org/urbanfloods WBI – Webinar, 3 April 2012

5. 12 guiding policy principles • Every flood risk scenario is different: there is no flood management blueprint. • Designs for flood management must be able to cope with a changing and uncertain future. • Rapid urbanization requires the integration of flood risk management into regular urban planning and governance. • An integrated strategy requires the use of both structural and non-structural measures and good metrics for “getting the balance right”. • Heavily engineered structural measures can transfer risk upstream and downstream. • It is impossible to entirely eliminate the risk from flooding. • Many flood management measures have multiple co-benefits over and above their flood management role. • It is important to consider the wider social and ecological consequences of flood management spending. • Clarity of responsibility for constructing and running flood risk programs is critical. • Implementing flood risk management measures requires multi-stakeholder cooperation. • Continuous communication to raise awareness and reinforce preparedness is necessary. • Plan to recover quickly after flooding and use the recovery to build capacity. WBI – Webinar, 3 April 2012

6. Understand the flood hazard and the impact • Understanding hazard requires better comprehension of types and causes of flooding, probabilities and occurrence. • Invest in producing and making widely accessible risk data! Invest in preparedness and response: • Flood hazard maps are visual tools for communication the hazard situation in an area. • Flood forecasting is an essential tool to provide people exposed to risk advance notice of flooding in an effort to save lives and property. WBI – Webinar, 3 April 2012

7. Climate Change and Flooding “Projected changes in climate extremes under different emissions scenarios generally do not strongly diverge in the coming two to three decades, but these signals are relatively small compared to natural climate variability over this time frame. Even the sign of projected changes in some climate extremes over this time frame is uncertain.” -IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation WBI – Webinar, 3 April 2012

8. Make Decision-making More Robust • Forget about optimal design and anticipating all risks • Traditional cost-benefit analysis does not work when dealing with catastrophic “tail” risk. • Instead focus on “robust” design, invest in data, preparedeness and response. • Develop robust indicators ALARP Principle WBI – Webinar, 3 April 2012

9. ALARP Principle Source: Ranger and Garbett-Shiels, 2011, LSE WBI – Webinar, 3 April 2012

10. Get the Balance Right Between ‘Structural and Non-structural Measures • Structural and non-structural measures do not preclude each other. Most successful strategies combine both types, striking the right balance between them. • Structural measures: Keeping the water away from the people • Are seen as less flexible, but flexibility can sometimes be incorporated, such as in the installation of wider foundations for flood defenses so that they can be raised later without strengthening the base. The purchase of temporary flood defense barriers can also be seen as a flexible alternative as they can be deployed when and where necessary, as flood risks change • Non-structural measures: Keeping the people away from the water [often has large co-benefits] • Many non-structural measures tend to be inherently flexible, e.g. early warning systems, forecasting and evacuation plans; and improved solid waste management systems. WBI – Webinar, 3 April 2012

11. Make Land-use Planning an Instrument for Risk Reduction: German Flood Control Act 2005 WBI – Webinar, 3 April 2012

12. Case Study: The LifE Project – Making Space for Water The LifE project adopted a non-defensive approach to flood risk management, which marked a shift from traditional thinking by permitting water into sites in a controlled manner to make space for water. Principles: • Living with Water: Adapting to increased flood frequency and severity, likely to happen with climate change • Making Space for Water: Working with natural processes to provide room for the river and sea to expand in times of flood and reduce reliance on defenses, where possible. • Zero Carbon: Providing all energy needs from renewable resources on site, such as wind, tidal and solar power. Policy lessons: • Flood risk management • Renewable energy • Development and amenity Baca Architects WBI – Webinar, 3 April 2012

13. Case Study: Integrated Flood Management Strategy for Ho Chi Minh City, Vietnam Urban growth in the periphery of the city had as a result newly-urbanized districts arising in sites at flood risk. Hard engineering or structural measures to minimize flood risk might be unsustainable under large hydrological, land subsidence and urbanization uncertainties. According to the Steering Center for Urban Flood Control in HCMC an integrated flood management strategy (IFMS) is most likely to be successful in reducing flood risk. Components: • Protection to an appropriate return frequency, determined by predictions using historical data and non-stationary analysis • Adaptation to cope with extreme events that surpasses design criteria • Retreat, which means restoring space for water to adapt to long-term climate changes. Policy lessons • Urban flood risk management cannot be associated solely with hard-engineered measures, but rather with an integrated and flexible approach in order to respond to future climate and socio-economic uncertainties. Ho Long Phi WBI – Webinar, 3 April 2012

14. Prepare for the Unexpected! “The basic issue is finding ways to build into near-term investments and choices an appropriate consideration of long-term trends and worst-case scenarios.” -Andrew Revkin WBI – Webinar, 3 April 2012

15. Questions for Discussion • Have you ever experienced floods? • If so, what types of flooding were these and what caused them? • Do you live in an urban center / area frequently exposed to flooding? • How do you prepare for a flood event? • What do you think would be the main challenge to improving flood resilience of your city/area? WBI – Webinar, 3 April 2012

16. Thank you! AbhasK. Jha ajha(at)worldbank.org Practice Leader, Disaster Risk Management East Asia and the Pacific The World Bank WBI – Webinar, 3 April 2012