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Urban flooding is a serious and growing development challenge for fast growing low and middle-income countries in East Asia, underscoring an urgent need to build flood risk management into regular planning of cities and towns, says a new World Bank guidebook released today.
Titled “Cities and Flooding: A Guide to Integrated Urban Flood Risk Management for the 21st Century”, the book provides operational guidance on how to manage the risk of floods in the face of urbanization, growing populations and long-term climate change trends.
“Urban expansion often creates poorer neighborhoods which lack adequate infrastructure and services, making them more vulnerable to floods. The poor are hit hardest, especially women and children,”
said Pamela Cox, World Bank Vice President, East Asia and Pacific Region.
“But rapid urbanization also means we have the opportunity to do things right the first time, so cities and towns can support sustainable development, saving lives and money.”
Floods are the most frequent among all natural disasters, and the East Asia and Pacific region, along with South Asia, is particularly vulnerable.
In the past 30 years, the number of floods in Asia amounted to about 40 percent of the total worldwide. More than 90 percent of the global population exposed to floods lives in Asia.
As developing countries in the region transition to largely urban societies, the concentration of people and assets has made urban flooding increasingly costly and difficult to manage. In addition to direct economic damage, floods also have long-term consequences such as loss of education opportunities, disease and reduced nutrition which may erode development goals.
According to the guidebook, the most effective way to manage flood risk is to take an integrated approach which combines both structural and non-structural measures.
The World Bank has suggested flood guidelines for Thailand for flood prevention and management as a method of managing expanding cities and a growing population.
- Building drainage channels and floodways;
- Incorporating “urban greening” such as wetlands and environmental buffers;
- Creating flood warning systems; and
- Land use planning for flood avoidance.
The key is getting the balance right, says the guidebook. While hard-engineered structures are effective when used appropriately, they can be overcome by natural disasters beyond their design capacity. They may transfer flood risk, reducing risk in one location only to increase it in another.
Implementing an integrated strategy effectively requires cooperation between different levels of government, public sector agencies, civil society, educational organizations and private sectors, as well as strong decisive leadership from national and local governments.
Many tools are available to help us better understand flood risk and its hazards
Web-based flood forecasting systems are an effective way to disseminate hydrological and hydro-meteorological data to a range of users. Mapping risk and vulnerability can be invaluable in directing resources appropriately to protect people.
For example, the World Bank is working with partners to support meteorological services in the Lower Mekong Basin. This will assist cities in Vietnam and Indonesia develop a medium term resilience plan that takes into account the uncertainties and risks from natural hazards.
Communications also plays a significant role in raising awareness and reinforcing preparedness. The guidebook warns that less severe disasters can be forgotten in less than three years.
As flood risk cannot be eliminated entirely, planning for a speedy recovery is also necessary, using reconstruction as an opportunity to build safer and stronger communities which have the capacity to withstand flooding better in the future.
“Recent large-scale disasters such as the earthquake and tsunami in Japan and the floods in Thailand and Australia emphasize the need for a new approach to disaster risk management and resilience,”
said lead author of the guidebook Abhas Jha, Lead Urban Specialist and Program Leader, Disaster Risk Management, World Bank East Asia and Pacific Region.
“We need to design systems that recognize the complex and uncertain nature of flood risk management and its impacts. Design should be comprehensive, flexible and iterative, being careful to avoid an over-reliance on any one given solution which may not be enough to counter the dynamic nature of risk.”