Ahmedabad: Slums are more vulnerable to summer heat, says new report

People who live in slums are facing a double whammy this summer due to the local high temperatures. A recent study undertaken by the faculty of Geo-Information Science and Earth Observation, University of Twente, Netherlands, regarding "The exposure of slums to the high temperatures of Ahmedabad", suggests that high land surface temperature is more prominent due to high heat capacity and makes slum pockets more vulnerable.

The study also suggests that locally, high temperature coincides with the presence of slums, indicating that places with slums are exposed to excessive heat compared to their surroundings.

"The study was conducted for four months, gathering satellite data and morphology-based local scale thermal patterns, which suggest slums are exposed to locally high temperatures and larger slums tend to be exposed to more intense locally high temperature. Data collection of the study is of high temperature or extremely high temperature of May month," said Jiong Wang, one of the researchers.

The study has taken data of the LST recorded by thermal satellite images with resolutions coarser than 250 meters used as a strong indicator of the variation of near-surface air temperature despite distinctively different meteorological and thermodynamic processes between near-surface air temperature and the LST.

The study reveals that although the highest LST is found in residential areas, the median LST at the residential areas is 29.59 °C and lower than 31.27 °C found at places with the presence of slums. Furthermore, 50% of the LST values are found at the high end of the plot of places with slums. High median LSTs are also found for commercial and industrial land uses with values of 30.89 °C and 30.61 °C. These areas are often densely built and industrial plants may not only absorb solar radiation but also emit anthropogenic heats.

Static water bodies may absorb energy during the day and become warm, whereas flowing water of the Sabarmati River can be much cooler. Commercial, industrial and mixed-use lands also tend to contribute to locally high LST. Water bodies can be positive because of the high specific heat capacity of water, which can lead to locally higher LST during night time.

"Slums defined as areas lacking access to satisfactory water, sanitation, durable housing or tenure security are with dense and poorly built forms and materials subject to extreme heat. We have fans, air coolers or air conditioners whereas the slum people do not have such capacity," said Dr Bhavin Solanki, an in-charge medical officer who has worked on Heat Action Plan of the Ahmedabad Municipal Corporation.

"Slum houses which have roofs made of steel or tarpaulin get hot very easily and they take time to cool down. So, when the Sun sets, while cement-concrete structures cool down rapidly, say within 40 to 60 minutes, in the slums, the process takes more time," added the doctor.

The civic body has taken several measures for slum dwellers to cope with extreme summer heat, which has reduced heat-related illnesses and deaths over the years.

THE FINDINGS

The study reveals that although the highest LST is found in residential areas, the median LST at the residential areas is 29.59 °C and lower than 31.27 °C found at places with the presence of slums.