Planning for Heat: Ward-Level Insights on Kochi’s LST Dynamics and Mitigation Strategies for Climate Future ^†

Most studies on Land Surface Temperature (LST) in tropical monsoon cities tend to treat the urban landscape as a single unit, often leading to broad and generalized recommendations for managing urban heat. This approach overlooks the LST variations within smaller units, such as municipal wards, which are crucial for effective, localized urban planning. Additionally, many of these studies rely on randomly selected satellite images from across seasons, potentially missing the true peak LST conditions necessary for accurate LST assessments.

In this study, the focus is on Kochi—a fast-growing coastal city in Kerala, India, characterized by its tropical monsoon climate and increasingly frequent and severe heat waves, especially from March to May. These conditions are driven by natural factors like the sun’s northward movement and high humidity from the surrounding seas, posing serious public health risks. Using Geographic Information Systems (GISs), remote sensing, and statistical analysis, the spatial variations in LST across Kochi’s 74 municipal wards over a ten-year period (2014–2024) was analyzed. A 25-year analysis (1997–2023) of daily air temperature data from the Indian Meteorological Department identified March 11–20 as the city’s hottest annual window. This period was used to extract satellite imagery from ESRI for in-depth analysis. Indicators such as the Normalized Difference Built-Up Index (NDBI), Normalized Difference Vegetation Index (NDVI), Modified Normalized Difference Water Index (MNDWI), and Normalized Difference Moisture Index (NDMI) and land cover percentage were used to identify the key drivers of LST at the ward level.

The findings show that built-up areas, roads, and industrial zones contribute to higher LSTs, while vegetation significantly reduces surface heat. Based on this, the study proposes ward-specific strategies such as increasing green cover, introducing green roofs, and altering road materials to reduce LST and improve thermal comfort. Beyond analysis, this study also models LST projections through 2040, identifying the wards within the city that can be critically affected by the rising temperature. These projections aim to inform prioritized and localized heat mitigation and adaptation strategies, providing valuable guidance for Kochi’s upcoming 2040 Master Plan, supporting climate-resilient urban development.