# 3. Methodology and data sources

As discussed, Mumbai is acutely vulnerable to recurrent floods. Given the acute income inequalities and 50% population residing in informal settlements, it is critical for the city to examine how recurrent floods impact the households and how do they cope with them. The aim of this study is to examine the **_exposure_** of the households to recurrent floods, **_vulnerability_** in terms of direct and indirect impacts of floods and their **_ability to respond_** . The study lays special emphasis on the **_poor households_** to understand their location in the flood‐prone areas vis‐à‐vis the non‐poor households, estimate the losses suffered by them on account of floods and examine the extent to which they can adapt to floods and have the ability to respond.

Table 1 describes the research questions, methodology and sources of primary and secondary data used in this study. To determine the **_exposure to flooding_** , the study seeks to understand the extent and spread of poor and non‐poor households located along the chronic and localized flooding spots. For this purpose, extensive database of the Planning Department of MCGM has been used. The Planning Department released Existing Land Use (ELU) maps (MCGM, 2015) as part of the exercise for creating the new development plan for the city. We have selected nine most flood‐prone wards and superimposed the chronic and localized flooding spots on the ELU maps using the GIS‐based platform. The chosen wards – F South, F North, K East, K West, H East, H West, L, M West and P North – represent three types of flood‐prone areas ‐ low‐lying areas, areas in the Mithi river flood plain and reclaimed areas. The demographics for these wards are given as Annexure A.1 and the maps showing land use in chronic and localized flood spots are given as Annexure A.2. The study has used 500 meter (m) buffer zone around the chronic spots and 200m zone around the localized spots to identify the vulnerable households in the flood‐prone areas.

In order to understand the **_vulnerability and impacts of floods_** as well as the **_ability to respond_** , the study has used detailed household surveys in the flood‐affected wards. Most damage assessment methods use insured exposure analysis to calculate the direct losses. This is particularly true for the developed world, where the coverage of insurance is very high. However, such methods are not able to capture losses suffered by the poor households, especially in developing countries, since they do not have the means to insure themselves. Yet, they are the most vulnerable sections to hazards like floods (Herweijer et al., 2009). Further, empirical studies for flood‐related economic damage assessment focus at macro or meso level and spatial aggregation of the affected assets is done over the whole administrative area using land use and hazard exposure maps (Merz et al., 2010). There are very few studies that try to assess the damage to single risk elements, such as, houses by carrying out detailed household surveys, e.g., Dutta et al., (2003), Khandlhela and May, (2006), Brouwer et al., (2007), Sales (2009) and Rabbani et al., (2013). For Mumbai, household surveys have carried out by Hallegatte et al. (2010) to examine the impact of the July 2005 extreme floods on marginalized population and informal economy: the economic impacts on assets and business losses for marginalized populations totaled USD $245 million. But this is likely an underestimate, as health 7