How cities can cope with climate change-induced floods

The repeated flooding of Bengaluru in the monsoon season of 2022 will become more common as the world becomes warmer and the atmosphere holds more moisture, increasing the possibility of extreme rainfall events. 

There were many meteorological reasons for the floods, but the lack of climate-adaptive infrastructure increased the intensity of the flooding and this needs to be addressed. 

“Climate change in cities will lead to increased rates of heavy precipitation, accelerated sea-level rise, exacerbated acute and chronic coastal flooding, drought, higher-than-average annual temperatures and extreme heat events,” the United in Science Report released on September 13, 2022. These, in turn, will exacerbate socioeconomic challenges and inequalities, it added. 

Such urban flooding events have also happened during the northeastern floods in June, especially in Assam, and during the devastating Pakistan floods of August. 

In the case of the urban flooding in Assam, the loss of wetlands (known as beels) around the various towns and cities was found to be the major reason. The degradation of these natural sponges of excess flood waters lead to the increase in the intensity in urban floods in the state. 

While a wide-ranging analysis of the health of Assam’s beels is unavailable, some studies of individual wetlands point to some of the possible causes. 

A 27-year (1992-2019) analysis of the Khamranga wetland close to Guwahati shows that the wetland degraded each year, its size decreasing by almost 22 per cent during the period. 

The study by Jayanta Goswami from the directorate of census operation in Assam and his team showed most of the decline occurred between 2000 and 2010. The study identified rapid urbanisation, industrial activities and lack of government intervention as the major factors for the degradation. 

Another study on the Deepor beel, also close to Guwahati and Assam’s only wetland of international importance under the Ramsar convention, showed a decrease in the storage capacity of the highly biodiverse site over the last two decades. 

The study by a team of researchers from various universities across the country showed that the storage capacity decreased by almost 27 per cent between 2001 and 2019. 

If these wetlands had been healthy, they could have lessened the impact of extensive flooding in Guwahati in June. The same could be said for other urban flooding events that have happened this year in Cachar, Darrang, Goalpara, Karimganj and Morigaon districts.

The report highlighted the adaptation measures that cities need to take to protect their populations, especially the most vulnerable, from frequent flooding of the sort that has happened in Assam, Bengaluru and Pakistan. 

“By continuing to address climate challenges as they occur, decision-makers put themselves in positions of responsive rather than proactive action”, the report stated. “There is an urgent need to address pressing ecological, social, economic, and climate justice needs within cities and settlements.”

The report also highlighted that in cities, rapid experimentation with inclusive decision-making and multi-level governance can take place. Both bottom-up approaches involving communities and top-down climate actions coming from the local governments can work together to make cities more resilient to climate change-induced events such as urban flooding. 

One of the key aspects of this is the monitoring, collection and analysis of high-resolution data over space and time on various aspects of urban climate and environment. 

In the case of floods, the Interdisciplinary Programme in Climate Studies (IDPCS) at the Indian Institute of Technology Bombay came up with an interesting early warning system for urban flooding based on crowdsourcing of information from citizens through the social networking platform Twitter. 

With the help of geotagged photos of water-logging people put on Twitter, the team of researchers wanted to generate real-time flood maps, which can help people avoid those areas while commuting. The data will also help them in creating a flood-risk map for future flooding scenarios. 

“Co-generation of knowledge and research while working with stakeholders is crucial to create usable climate data at the city level,” said the United in Science report.  

“The need for urgency is upon us. The scientific understanding of climate change has reached the highest degree of certainty ever. Awareness of urban-focused risk, including hazards, vulnerabilities and exposures, has increased,” said the report. 

Reducing greenhouse gas emissions of cities, along with adaptation, is also important for mitigation of climate change, it added. 

“Cities have a vital role to play by implementing inclusive, urgent, and scaled-up urban climate action required to enhance resiliency, limit the degrees of warming, and keep the planet liveable,” concluded the report. 

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