Urban Floods are Becoming More Deadly

South Asia is in its peak monsoon season, and floods are increasingly becoming grave threats to the region’s population.

South Asia is in its peak monsoon season, and floods are increasingly becoming grave threats to the region’s population. Nepal, this year, is facing massive impact from floods and landslides. I ponder on how climate change will exacerbate these events and make the lives of the less well-off people even more difficult.

In the last decade, Asian cities like Mumbai, Dhaka, Kolkata, Chennai, Karachi, Manila, and Bangkok have faced devastating floods. Cities that are today facing massive pressures of urbanization, like Kathmandu, Phnom Penh and Ahmedabad are also facing more floods. In 2017, Nepal, Bangladesh and places in India like Bihar and Mumbai faced massive flooding that killed 1,200 people and displaced about 40 million people. That same year in 2017, Vietnam, Central African Republic, Nigeria, Niger and Sierra Leone also faced heavy rains, inundation and mudslides, triggering massive losses and deaths.

Even cities in the developed world are becoming increasingly prone to flooding disasters. 2017’s Hurricane Harvey in Texas broke all past records when, in only a matter of days, 34 billion cubic metres of rain turned Houston’s highways into rivers and inundated thousands of homes. Harvey was followed a few days later by Hurricane Irma, which devastated southern Florida, and some days after by the catastrophic storm Maria devastating the Dominican Republic and Puerto Rico.

More flood disasters in cities are a result of unregulated urban expansion, high intensity rainfall, drainage congestion and failures of urban governance. Urban expansions today have ignored the science of urban hydrology and paved over green spaces, grassland and open space. Flood water evacuation routes are systematically constrained or even closed. Many smaller streams that flow through cities and settlements have been walled and covered and turned into a sewer. Naturally occurring wetlands and ponds that could buffer flood peaks, are systematically encroached upon to expand coverage for real-estate.

Cities are also facing increasing impacts from floods because of weaknesses in preparedness and recovery efforts as well. This will worsen flooding in South Asian urban regions in the coming decades as more and more people concentrate into cities. If rainfall anomalies, similar or worse than those we see today, become common and if sustainable risk-mitigation strategies are not mainstreamed, urban areas may continue to face severe well-being gaps.

Conventional South Asian responses to flood mitigation are infrastructure led, with a focus on embankments and levees along riverbanks. While these structures may provide some immediate benefits, they can cause catastrophes when faced with extreme conditions. Embankments and levees block rivers from flowing into the main rivers and cause inundation outside of the embankment.

Embankments that are poorly built and maintained, which is more often the case than not in South Asia, magnify damages in river basins. Many embankments are regularly breached, and the river ends up causing more loss and damages than if an embankment wasn’t there in the first place.  The 2008’s Koshi embankment breach in Nepal’s Sunsari District stands as a stark warning on the damages such structures can bring about. The breach affected more than 50 thousand people of Sunsari District and about 3.5 million people of Bihar. It also brought major damage to infrastructure and agriculture.

Urban Floods are Becoming More Deadly

(source: Dixit 2003, Basic Water Science)

Influence of climate change

Global warming and climate change will make life for the less well-off population worse. The UN Habitat report reminds us that more cars, more badly built and poorly maintained roads, dramatic changes in natural landscapes, and ‘more well-serviced richer neighbourhoods and gated communities’, can exacerbate extreme weather events including floods. In early monsoon months of 2021, parts of Nepal’s upper mountain region also recorded rainfall events that had not been experienced before.[1]

The millions of vulnerable people in cities of the global south face heightened exposure from disasters also because of their governments’ low economic and institutional capacities. The less well-off families typically live in vulnerable locations in cities, have limited access to basic services, and have limited or no voice in policy-making. Lack of secure livelihoods further leads to higher levels of vulnerability to disasters. Thus, when disasters like floods strike, majority of the population is pushed further towards marginalization.

Rethinking urban future

With increasing climate change, cities face many “unknowns”, and therefore investment is needed for disaster preparedness and recovery. Early warning systems for cyclones established in the India have provided enough lead time for evacuation and saved lives. Flood warning mechanisms in Nepal that combine community participation with high level science and use of ICT have also saved lives. Such mechanisms need to be upgraded, replicated and scaled.

In past few weeks (of 2021), many cities across the world in Germany, Belgium, China, India and Middle east faced floods triggered by unprecedent rainfall. In China, for example, one year’s worth of rain came in one day, which expert argue is caused by climate change. Flood risks have amplified many times.

Globally city policies seem driven more by economic considerations and asset values rather than by holistic measures of livability and lower disaster risks. Urban planners, architects, engineers, designers, and policy-makers need to engage city dwellers in designing livable, green, inclusive and people friendly cities with low disaster risks including that from floods.

The basic premise for policy and project design should be that all evacuation routes, for people as well as for the safe discharge of floodwaters, must remain uninterrupted. Minimising increasing risks of climate change requires significant changes in the way urban areas are developed and governed.

End Notes:

[1] Jibanmani Paudel studying impacts of climate change in Naso Valley of the Manang District reminisces locals who told him, “the rainfall in the valley has become like Lamjunge Pani (meaning rainfall of higher intensity in mid hills)”. See Ke Sikne Himalko Badhi Pahiro Bata, July 12 2021, Kantipur.  From April 2021 to June, 2021 floods in Nepal swept away more than 18 motorable bridges with a damage estimated at NPR 1.25 billion. (https://www.onlinekhabar.com/2021/07/979768). While the trigger was rainfall induced floods, this disaster brings to the fore many questions about precipitation pattern, the quality of design and construction of bridges including infrastructure, compliance to policies, engineering practices and engineering education. Himanchal Pradesh in India also faced cloudburst and flash floods in July 2021.

This article is adapted and curated from “Houston, you have a problem”
https://kathmandupost.com/opinion/2017/10/03/houston-you-have-a-problem by Ajaya Dixit and Richard Friend. We acknowledge and thank The Kathmandu Post.

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