How did old Tokyo overcome floods and poverty?

There is concern that more frequent flooding around the world will accelerate the vicious cycle of poverty, particularly in developing countries. There is also hope that flood control as a climate adaptation measure will bring significant socioeconomic benefits in the long term, such as improving the livelihoods of the poor, but the effects have yet to be proven. Tokyo, one of the world's largest cities, experienced frequent flooding during the Edo period (1603-1868). Did Edo, as Tokyo was then called, have the same problems with flooding and poverty that we see in developing countries today? And how did they overcome them? In this study, we collected and integrated a wide range of historical records on past floods and poverty, which historians had previously studied separately, and quantitatively demonstrated the relationship between the earliest floods and poverty. We found that areas with large numbers of poor people were more vulnerable to flood damage. It also showed that flood control exacerbated inequalities during the Edo period, when there were significant technological and budgetary constraints, but that later, as flood control was strengthened, socioeconomic inequalities were reduced. This research is the first to demonstrate the long-term socioeconomic impacts of flood control, and it presents the long-term socioeconomic impacts of climate adaptation and disaster mitigation investments for developing countries that, like Tokyo in the past, face the problem of flooding and poverty. Based on the findings of this research, we would like to contribute to deepen the discussion of social hydrology regarding the impact of flood control on long-term socioeconomic development.