Urban Heat Island Mitigation in Mumbai's Informal Settlements: A Community Mapping Case Study

Thesis Abstract

Urban heat island (UHI) effects within Mumbai’s informal settlements pose acute overheating risks, impede daily activities, and exacerbate health vulnerabilities among densely populated communities lacking adequate cooling and shading. This study investigates how community-led mapping can inform targeted mitigation strategies by integrating spatially explicit socio-ecological data to understand exposure, vulnerability, and adaptive capacities in informal settlements of Mumbai. The aim is to evaluate the effectiveness of participatory mapping as a mechanism for identifying microclimatic hotspots and informing locally appropriate UHI mitigation interventions. Specific objectives are to (a) quantify intra-urban temperature differentials at the settlement level using a transect-based thermal survey; (b) assess housing, street geometry, vegetation cover, materiality, and water availability as predictors of indoor and outdoor heat exposure; (c) examine community-perceived heat stress, coping practices, and barriers to adaptation through thematic inquiry; (d) develop a GIS-based, community-augmented UHI model to prioritize mitigation actions; and (e) generate policy-relevant recommendations and a scalable framework for participatory climate adaptation in informal urban contexts. Methodologically, the study adopts a mixed-methods design anchored in a transdisciplinary paradigm, combining quantitative environmental measurements with qualitative social insights. The population comprises residents of two large informal settlements in Mumbai, selected through purposive sampling to ensure diversity in housing typologies, tenure arrangements, and access to water and electricity. A representative sample of 240 households will be surveyed, complemented by 60 in-depth interviews with community leaders, women’s groups, and health workers, and 20 focus group discussions with residents. Instrumentation includes (i) a mobile sensor network deploying calibrated infrared thermometers and HOBO data loggers to collect ambient air temperature, surface temperature, and humidity at multiple times of day over a three-month monsoon-to-dry-season window; (ii) a structured household survey capturing sociodemographic information, housing materials, building geometry, cooling practices, health status, and heat-related behaviors; (iii) a participatory community mapping workshop using GIS tablets to annotate microclimatic hot spots, shading, green cover, and water features; and (iv) semi-structured interview guides to elicit perceptions of heat risk and barriers to adaptation. Validity and reliability will be established through pilot testing, intercoder reliability checks for qualitative data, and triangulation across data sources. Data analysis proceeds with quantitative treatments including descriptive statistics, multivariate regression to identify determinants of indoor and outdoor heat exposure, and mixed-effects modeling to account for clustering within compounds. Spatial analysis will implement hotspot detection, Moran’s I for spatial autocorrelation, and a GIS-based UHI index at the community scale. Qualitative data will be analyzed via thematic analysis, informed by the Theory of Planned Behavior and the Social-Ecological Model, to interpret behavioral determinants and community readiness for adaptation. An integrative analytical framework will triangulate quantitative heat exposure patterns with qualitative narratives to construct a context-specific UHI risk profile and a priority-setting matrix for mitigation actions such as reflective roofing, enhanced shading, temporary cooling centers, and water-sensitive urban design interventions. The study will reference relevant theories including the Urban Ecology Theory and the Environmental Justice framework to examine equity dimensions of heat risk and access to adaptation resources. Expected findings anticipate pronounced intra-settlement heterogeneity in heat exposure driven by building materials, lack of ventilated spaces, narrow street canyons, and uneven green cover, with associations between higher exposure and elder/child vulnerability, informal housing tenure, and limited access to cooling resources. The participatory mapping process is expected to yield high-resolution, resident-endorsed mitigation priorities, revealing feasible, low-cost interventions with strong community uptake. The contribution to knowledge lies in demonstrating the utility of community mapping as a robust, scalable tool for UHI assessment and intervention planning in informal settlements, integrating empirical thermal data with social dimensions to produce an actionable, equity-focused mitigation framework. The study concludes that coupled physical and social data-informed strategies—tailored microclimate interventions, community governance priorities, and simple, low-cost cooling technologies—can substantially reduce heat exposure and improve health outcomes. Policy recommendations include formalizing participatory mapping within municipal climate resilience planning, prioritizing shading and ventilation improvements in high-exposure zones, and fostering cross-sector collaboration among municipal authorities, non-governmental organizations, and community groups to implement and monitor UHI mitigation programs.