A recent World Bank report has revealed that infrastructure and roads are contributing to a significant rise in night-time temperatures in major Indian cities, exacerbating the urban heat island effect. The report, titled 'Towards Resilient and Prosperous Cities in India,' highlights that night-time temperatures in these cities are exceeding those of surrounding rural areas by 3-4 degrees Celsius throughout the year. Lucknow experiences an even more pronounced difference, with temperatures as much as 5 degrees Celsius higher at night. Chennai and Surat also face significant temperature increases.

The primary cause of this phenomenon is the abundance of structures, roads, and other infrastructure that absorb and re-emit solar energy, especially at night. Common building materials like concrete and asphalt have thermal properties that cause urban areas to heat up more than rural areas. This is further intensified by the limited green spaces and increased heat generated from human activities like transportation and air conditioning. This phenomenon increases the risk of heat waves in cities, negatively impacting human health and economic productivity.

The report projects that heat hazards will increase significantly in the coming decades, with the magnitude of the increase depending on the global emissions scenario. Under a high global emission scenario, residents of densely built neighborhoods in Chennai, Lucknow, and Surat will experience between 30% and 50% more extremely hot days and nights by 2050 than at present. In Surat, the number of hot nights is expected to rise from 65% to 82% of nights per year.

The World Bank report also highlights the increasing risk of pluvial flooding (surface water floods due to heavy rains) in Indian cities. It estimates that the risk of pluvial flooding could increase by 73-100% in the next 50 years. Among the cities studied, Delhi has the maximum built-up area exposed to pluvial floods. Without any remedial actions, annual losses from pluvial flooding are expected to reach $5 billion by 2030, and between $14 to $30 billion by 2070.

Delhi's vulnerability to floods is a growing concern, with the city having experienced several major floods in the past. Factors such as unpredictable rainfall patterns and the release of excess water from upstream sources contribute to the city's flood risk. Encroachment on the Yamuna floodplains, siltation, and faulty operation of barrages have also been identified as reasons for the floods.

To mitigate the impact of rising temperatures and flood risks, the World Bank report suggests investing in green and resilient urban development, including housing, transport and municipal services. Increasing the urban tree canopy and adding green spaces can help lower temperatures. Other options include green roofs, passive daytime radiative cooling applications, and the use of lighter-colored surfaces and less absorptive building materials. Improving drainage systems, reviving water bodies, and desilting drains are also crucial steps to mitigate flood effects.