MDP is relatively more suitable to identify the poorest households, whereas monetary measures are more suitable to measure economic progress more broadly.

# **2.4 Cyclone risk in coastal Bangladesh**

The coastal zone of Bangladesh is the case study area in our analysis. The coastal zone of Bangladesh is comprised of 19 districts (second administrative units in Bangladesh) covering 47,200 km<sup>2</sup> , which was home to approximately 37.3 million people in 2011 (Bangladesh Bureau of Statistics, 2012), which has increased to almost 43.8 million people in 2021 (preliminary 2021 Census data). While significant progress has been made to improve wellbeing in the coastal zone, as illustrated by the decreasing (infant) mortality rate, poverty reduction, education enrollment, and access to water and sanitation (Hossain et al., 2016), the coastal population is lacking in terms of development compared to the country as a whole. For instance, 60 percent of the coastal Upazilas (third administrative units in Bangladesh) have an above average poverty incidence (which was 24.3 percent in 2016) (Bangladesh Bureau of Statistics, 2016).

The coastal zone is low-lying, with almost two-thirds of the coastal land being located less than three meters above mean sea level (MSL). The large amount of low-lying land, combined with the high population density (~1000 people per km<sup>2</sup> ) and the Bay of Bengal being prone to frequent tropical cyclones, make the coastal regions (in particular exterior coastal upazilas) vulnerable to the impacts of cyclone-induced wind and storm surges, as well as monsoon flooding (interior coastal upazilas). On average, a tropical storm (winds >63 km per hour) hits Bangladesh every year, while a Category I cyclone or higher (winds >118 km per hour) hits the coast every three years (Islam and Peterson, 2009; Dasgupta et al., 2014). Storm surges generated by cyclones can be very large (3 to 5 meters for a severe cyclone), which is attributed to the re-curvature of the cyclones in the Bay of Bengal and the shallow, funnel-shaped, coastal shelf that amplifies surges (Islam and Peterson, 2009; Dasgupta et al., 2010). As a result, storm surges can travel far inland along the tidal river branches and cause high water levels at embankments hundreds of kilometers from the coast. It has been estimated that tropical cyclones alone cause average annual losses (both damages and losses for all sectors) of almost 1 billion USD, while past events have recorded losses of up to 3.8 billion USD (TC Sidr in 2007) and 3.0 billion USD (TC Gorky in 1991) (Ozaki, 2016).

The cyclone-induced risk, in terms of physical asset damages, is expected to change in the future in coastal Bangladesh. First, climate change may change the frequency and magnitude (e.g. wind speed) of cyclones in the region. Second, sea-level rise increases the height of storm surges, resulting in more widespread inundation. Third, human-induced and natural subsidence, leads to a large relative sea-level rise, which can more than double the expected increase in water levels (Nicholls et al., 2021). Fourth, future economic development and population growth may increase the number of exposed assets in the coastal zone, which can contribute to changing risk, though population projections are highly dependent on the expected migration rates in the region (Chen and Mueller, 2018). Altogether, adaptation is required to prevent risk from increasing and prevent climate migration from the coastal zone.

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