Why Bengaluru is experiencing heavy rainfall: An in-depth explainer on the causes and consequences

In the last few days, Bengaluru has witnessed an unseasonal downpour, with rainfall levels exceeding 100 mm in some areas. This heavy rainfall has disrupted daily life, leading to severe waterlogging and traffic congestion, with certain regions experiencing flooding. While rains in Bengaluru are common during the monsoon season, the intensity and timing of this rainfall have raised questions. Let's explore the meteorological reasons behind this unusual weather pattern and understand its impacts on the city.

Also Read:IMD issues Orange alert for Bengaluru amid forecast of intense rainfall

Meteorological Causes Behind Bengaluru’s Unseasonal Rainfall:

1. Cyclonic Circulation Over the Arabian Sea: The India Meteorological Department (IMD) has identified an upper-air cyclonic circulation over the east-central Arabian Sea, which is drawing significant moisture towards Bengaluru. This system is likely to intensify into a low-pressure area, further increasing the rainfall in the region.
2. North-South Trough: Another major contributing factor is the north-south trough stretching from Maharashtra to Kerala, passing through Karnataka. This trough has enhanced atmospheric instability, causing moisture to converge and leading to the development of thunderstorms and heavy rainfall. The increased atmospheric instability has led to higher rainfall intensity.
3. Urban Heat Island Effect: Bengaluru's rapid urbanization and extensive concrete surfaces have made the city more susceptible to heavy rainfall. The heat island effect, caused by the high density of buildings and concrete, increases the city's temperature, drawing more moisture from the atmosphere. This intensified moisture concentration then results in heavier rainfalls, overwhelming the city's drainage systems.
4. Loss of Natural Water Bodies: The city's urban sprawl has led to the filling of lakes and wetlands that once acted as natural catchment areas for rainwater. The loss of these water bodies has reduced the city's natural ability to manage rainfall, leading to increased flooding in low-lying areas.

Widespread impacts of the rainfall

1. Severe Waterlogging and Traffic Disruptions: Many areas of Bengaluru are struggling with severe waterlogging, especially in low-lying neighborhoods like Sai Layout. Streets have turned into rivers, causing traffic congestion, making commuting difficult, and leaving several parts of the city inaccessible.
2. Strain on Drainage Systems: The city’s drainage systems are struggling to cope with the volume of water, leading to the overflow of drains and flooding in residential areas. Many areas have seen rainwater enter homes, damaging property and possessions.
3. Impact on Health and Safety: Standing water in flooded areas poses significant public health risks. The accumulation of stagnant water can become a breeding ground for mosquitoes, leading to potential outbreaks of diseases like dengue and malaria. The risk of waterborne diseases like cholera and typhoid also increases as drainage systems fail to function properly.
4. Disruption to Daily Life: The downpour has disrupted daily activities across the city, with schools, businesses, and public transport facing delays and closures. People have found it difficult to go about their usual routines, as the rains have resulted in poor visibility, accidents, and delays.
5. Vulnerable Communities Affected: Low-income and informal settlements, which are often built in flood-prone areas, have been hit the hardest. These communities, which lack proper infrastructure, are facing severe flooding, leading to temporary displacement for many families.
6. Economic Consequences: The rains have affected Bengaluru's economic activities, particularly in sectors such as retail, hospitality, and transport. With businesses facing disruptions, employees unable to commute, and public services struggling, the financial impact of these rains is substantial.