CONTEXT – Bengaluru has become a heat island amidst its celebrated weather, overwhelmed by concrete, pollution, and water scarcity, leading to concerns about its future

URBAN HEAT ISLAND (UHI)

• UHI refers to localized areas within a city experiencing notably higher temperatures than their surroundings.
• This temperature difference is primarily due to the widespread use of heat-absorbing materials like concrete in urban structures.
• Causes of UHI:
  • UHI is caused by the trapping and retention of heat within urban areas, hindering its dissipation.
  • Heat-absorbing materials in buildings and infrastructure contribute significantly to this phenomenon.
• Temperature Disparity:
  • The temperature difference between UHI areas and their surroundings can range from 3 to 5 degrees Celsius.
  • This significant temperature variation exacerbates heat-related issues and discomfort in urban environments.

SITUATION IN BENGALURU

• Bengaluru’s urban areas experience higher temperatures due to concentrated concrete infrastructure, which absorbs and re-emits heat more than green spaces and water bodies.
• This “heat island effect” has worsened summer discomfort across the city.
• Rising Temperatures and Climate Trends:
  • Recent studies show a nearly one-degree rise in Bengaluru’s average temperature over the past 42 years.
  • The temperature increase has been more pronounced in the last two decades, leading to higher evaporation rates of water bodies.
• Impact on Water Resources:
  • Reduced rainfall in the past three years has directly affected groundwater recharge and reservoir replenishment.
  • This situation has contributed to the current water crisis in Bengaluru, highlighting the urgent need for sustainable water management strategies.

ANALYSIS OF CAUSES

• Rapid Concretisation and White-Topping of Roads:
  • The city’s roads are being extensively concretized, reducing options for rainwater percolation and groundwater recharge.
  • This trend, known as “white-topping,” has escalated for decades, impacting Bengaluru’s ecological balance negatively.
• Environmental Consequences of Unplanned Urbanisation:
  • Recent studies, like the one by the Indian Institute of Science (IISc), highlight adverse impacts, including a decline in forest cover (26%) and agricultural lands (23%) alongside a sharp increase in paved surfaces (urban areas saw a 34% increase in five decades).
  • This rapid urbanization has adverse ecological and environmental effects, exacerbating issues like the urban heat island effect.
• Rapid Concretisation and White-Topping of Roads:
  • The city’s roads are being extensively concretized, reducing options for rainwater percolation and groundwater recharge.
  • This trend, known as “white-topping,” has escalated for decades, impacting Bengaluru’s ecological balance negatively.
• Environmental Consequences of Unplanned Urbanisation:
  • Recent studies, like the one by the Indian Institute of Science (IISc), highlight adverse impacts, including a decline in forest cover (26%) and agricultural lands (23%) alongside a sharp increase in paved surfaces (urban areas saw a 34% increase in five decades).
  • This rapid urbanization has adverse ecological and environmental effects, exacerbating issues like the urban heat island effect.
• Dire Warnings and Future Projections:
  • Projections suggest that Bengaluru could soon be overwhelmed by paved surfaces, reaching over 98% coverage, with 69.9% of the Bangalore Urban district becoming paved areas.
  • Loss of vegetation, water bodies, and open spaces could amplify the urban heat island effect, leading to increased ambient temperature and humidity, causing heat stress and related health issues.

WHAT CAN BE WAY FORWARD

• Call for Sustainable Solutions:
  • Experts emphasize the need for “water urbanism,” making the city’s landscape porous to mitigate heat island effects and recharge groundwater.
  • Creation of mini forests within BBMP wards and prioritizing native vegetation can significantly reduce ambient temperature and enhance water retention.
• Importance of Cluster-Based Development:
  • Decongesting the city and adopting cluster-based development can ease infrastructure strain and reverse migration trends.
  • Locating industries based on resource availability can reduce environmental impact and promote sustainable urban growth.
• Policy Considerations and Public Awareness:
  • Despite these insights, policy changes and public awareness remain crucial for sustainable urban development.
  • The urgency to address heat island effects, environmental degradation, and infrastructure challenges requires proactive measures and long-term planning