Kolkata and Mumbai have been identified as the top seven megacities of the world most vulnerable to urban floods along with Shanghai, Bangkok and Hoh Chi Minh city, in a new report.
“Towards a world of cities in 2050”, published by PBL Netherlands Environmental Assessment Agency (PBL), is an important input report for the forthcoming fourth UN-Habitat report “Global report on water and sanitation in cities of the future”.
By 2050, the world’s population is expected to grow by more than 2 billion people to 9 billion and around 70 per cent of the world’s population is expected to live in urban environment, reminds this PBL report once again (See ‘World Urbanization Prospects, The 2011 Revision Link’). It also reiterates and cautions that most of this growth will take place in developing countries, specifically in their cities.
This PBL report, therefore, explores and projects socio-economic, environmental trends for 2050. It shows that major water-related challenges lie ahead for these cities, including access to clean drinking water, proper sanitation and protection against floods. However, the study also shows that knowledge and technologies are available that may strongly reduce water-related stresses and risks for the human population. It is based on recent PBL scenario studies that include OECD environmental outlook, which covers these topics at the global level and the “Roads from Rio”, that focused on potential policy pathways for achieving globally agreed policy targets, provided significant inputs in this report.
Access to water projected to improve, not sanitation
In the coming years, substantial progress may be expected in access to safe drinking water and improved sanitation. The Millennium Development Goals that target water supply have already been attained, globally, and further progress is projected. But as far as progress on access to sanitation is concerned, the current developments show that many countries still lag behind, particularly in sub-Saharan Africa.
The MDG sanitation target will not be met (see ‘WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation (JMP) - 2013 Update’); by 2030 more than two billion people will still lack basic sanitation facilities. In 2030, the majority of those without improved sanitation will live in developing countries, and this proportion will continue to grow towards 2050, the report says.
So what will be the cost of universal access to improved water supply and sanitation by 2050? According to policy simulations in this report, universal access to improved water supply and sanitation by 2050 will mean an average investment of USD 1.9 billion globally each year till 2030 and USD 7.6 billion would be required annually between 2031 and 2050 (See table from report).
Population growth will outpace sewerage installation
A century ago, the dominant pathway for nutrients was their reuse in agriculture; today, the dominant pathway is for them is to end up in surface water. This results in eutrophication and pollution of rivers, lakes and coastal waters. Continued investment in waste-water treatment in developed countries is expected to stabilise and restore surface water quality. But sub-Saharan Africa and South Asia, population growth will be higher than the growth in sewerage systems and the quality of surface water in this region and other countries is expected to deteriorate between 2010 and 2050 (see table).
|Asian and African sewerage connection and treatment systems in 2050
- The number of households connected to a sewerage system will increase in all regions.
- The largest increase will be in East Asia, South Asia and sub-Saharan Africa.
- The smallest increase in sewerage connection will be in the Russian region and Central Asia and in developed countries.
- Most wastewater in developed countries, by 2050, will be treated using tertiary treatment.
- In developing countries, the sewage effluent will be treated using a primary or secondary treatment plant, or discharged without treatment.
- In sub-Saharan Africa and South Asia, population growth will be higher than the growth in sewerage systems.
Hence, this report calls for several measures to improve sanitation, and combine it with adequate waste-water management and treatment systems. The growing cities will have to invest significantly in developing large-scale and efficient sanitation, sewerage and waste-water treatment systems. Developed countries should plan for advanced wastewater treatment with more nutrient removal and a lower energy consumption or small-scale advanced treatment systems, while the developing countries with a low degree of connection to sewerage systems and no wastewater treatment, should opt for small-scale solutions with sludge treatment, says the report.
Local options, practical solutions
Realising that expansion of expanding sewerage systems in several countries specially the African nations will be expensive, the reoport says that new technologies and incentives for local reuse may provide an alternative to centralised options. There should be a particular focus on dealing with faecal sludge from septic tanks, pit latrines and public toilets, since this is by far the most common form of waste water in the developing world, advises PBL and recommends infrastructural support for faecal sludge management. The Sanergy model from Nairobi is an interesting example of integrated sanitation system and the profitable waste business, too.
The report also suggests agreements between the countries as a critical measure to improve water quality in the transboundary catchment and prevent excessive pollution of coastal waters.
By 2050, 15% of global population will live in flood-prone areas Leaving aside the effects of climate change, the number of people living in flood-prone areas is projected to be 1.3 billion by 2050, or around 15 per cent of the global population. As urban areas expand, hundreds of trillions of dollars in infrastructure, industrial and office buildings and homes will be increasingly at risk from river and coastal flooding – particularly in Asian cities. The most vulnerable megacities will be Kolkata and Mumbai in India, Dhaka in Bangladesh, Jakarta and Bangkok in Thailand, Shanghai in China and Ho Chi Minh City in Vietnam.
Of all weather-related disasters, floods annually affect the most number of people. Over the past 30 years, on an average, almost 90 million people were affected by flood disasters each year. The reported global economic losses due to floods amount to almost USD 20 billion a year. But a wide range of flood risk strategies can strongly reduce the flood risks, both with respect to loss of lives and economical losses, says the PBL study.
It considers high concentrations of assets and people in cities as an opportunity for highly cost-effective flood protection strategies and says that the costs of adequate flood protection measures may not necessarily be high.
Cost of inaction In 2010, the annual exposed GDP to floods was US $435 billion, or 1 per cent of total global GDP. With no action, the GDP annually exposed to floods is projected to increase rapidly to an estimated US $1,797 billion by 2050 – a growth of 313 per cent in comparison to 2010, warns PBL. The annual exposed GDP will grow tremendously in all regions, especially in South Asia, if the flood protection measures are not increased.
As the cities and the urban population grow, the environment and developmental problems, too, will grow with them and this includes the increased exposure to urban floods, says the report, specially stressing on the Asian cities in India, China and Thailand (See ‘Urban Growth Modeling to Predict the Changes in the Urban Microclimate and Urban Water Cycle for the relationship between unprecedented urban growth and urban floods in three growing Asian cities – Beijing, Delhi and Can Tho, Vietnam’).
|Top seven most vulnerable cities to floods in 2050
- Ho Chi Minh
Flood warning for Kolkata and Mumbai
India will add another 497 million to its urban population between 2010 and 2050, according to the UN's 2011 'Revision of the World Urbanisation Prospects' report.
A World Bank study submitted to West Bengal government in 2012 predicted a loss of Rs 10,800 crore in the city by 2050 because of a one-in-100-years flood coupled with climate change impacts.
Last year, a study published in Nature Climate Change has already warned that Mumbai and Kolkata would lose $6.4 billion and $3.4 billion annually, by 2050 due to flooding even if they upgrade their protection. IPCC report on climate impacts published in 2014 has also said that Mumbai and Kolkata will be victims of the rising coastal and urban flood risks.
Most vulnerable and least prepared.
In most urban areas, the flood risks are unequally distributed. Low income groups often live in most flood–prone areas and are more vulnerable to floods because of poor quality, insecure and clustered housing, inadequate infrastructure and inadequate provision for emergency and post-disaster recovery services. This inequity in urban flood risks is seen both in the developing and developed countries and must be considered for effective and efficient flood risk planning and adaptation, says the PBL report.
Smart water approach
The report suggests an integrated flood-risk strategy with an overview of possible non-structural and structural measures grouped by flood-related measures and conditional measures.
It calls upon all stake holders to participate in making cities flood-proof and details the multiple governance challenges that include integration of flood risks in urban planning, integration of climate change in urban planning and design, integration of equity and environmental justice in flood risk strategies and urban planning. An effective communication between various stakeholders on flood risks and flood risk management plans is also extremely important for reducing the loss in human lives and the economic loss, says the PBL report. It also calls upon the civic authorities to think about comprehensive insurance programmes to cover future losses.
The second World Reconstruction conference held in Washington from September 10 to 12, too, was in favour of e¬fficient and effective recovery strongly promoted through systematic dissemination of knowledge, tools, guidance, lessons on recovery and the global leaders say that disaster recovery should be adequately articulated in Post-2015 framework for Disaster Risk Reduction.
India’s minister of state for home affairs, Kiren Rijiju, who led the Indian delegation in this conference, said that the country is increasingly focusing on mainstreaming disaster risk reduction into development planning and is on the threshold of creating an Indian Recovery Framework that would outline specific steps required to be taken for effective and efficient recovery along with financial commitment.
Taking a note of the inter-connections between urban water supply, sanitation, waste-water treatment infrastructure and urban expansion, the PBL report recommends an integrated urban development approach to reduce flood-risks in the expanding cities. The PBL study calls for a “smart water” approach by “smart cities” of the 2050 with smart and climate-proof design of sewage and waste-water treatment systems, urban development plans to prevent urban flooding and reduce flood risks.
India which has been witnessing severe urban floods for several decades (see ‘Now it is floods’) and with ambitious plans for 100-new smart cities must take a note of this and plan for smart urbanisation instead of mindless urbanisation. The National Conclave of States/UTs on Smart Cities held in Delhi on September 12, too, discussed the way ahead for these smart cities.
Support the victims of J&K floods
As you read this, Jammu and Kashmir is battling one of the worst urban floods in 60 years with rivers in the region in spate following days of incessant rains. Over 30 per cent of the capital city, Srinagar, is under flood waters. More than 1million people are affected in Jammu division.
Share this GOOGLE CRISIS map for Jammu and Kashmir, updated with satellite images. This map will help all agencies, institutions and the individuals involved in the rescue operations reach thousands of people stranded in flood-affected areas.
See also the new CSE analysis, J&K floods a grim reminder of increasing climate change impact in India.
Interactive: Floods 2014: Nature's fury around the world
Cities and flooding: a guide to integrated urban flood risk management for the 21st century
Developing innovative strategies for flood-resilient cities
Five feet high and rising: cities and flooding in the 21st century
Flood risks, climate change impacts and adaptation benefits in Mumbai
Climate change 2014: impacts, adaptation, and vulnerability - summary for policymakers (IPCC Climate Report, Fifth Assessment, WGII AR5)