Transmission of flood damage to the real economy and financial intermediation: Simulation analysis using a DSGE model

We assess physical risk associated with floods in Japan, using a dynamic stochastic general equilibrium (DSGE) model. We construct a model that incorporates transmission mechanism of floods and estimate the model using the data of flood-induced damage to capital stock and public infrastructure collected by the government in the last 40 years. The result of the analysis is threefold. First, a flood that reduces the private capital stock by about 0.1% as a direct effect causes GDP to fall by about 0.1% in the first period, with a gradual recovery to pre-flood level. Second, floods dampen GDP through multiple channels. From the supply side, a decline in capital stock inputs and total factor productivity (TFP) reduce GDP. From the demand side, the balance sheets of firms and financial intermediaries are impaired, resulting in disruptions to financial intermediation and depressing GDP. Based on our estimates, all these channels are quantitatively comparable in magnitude. Third, the quantitative impacts of flood shocks on GDP up to now have been minor compared to the standard structural shocks that are considered important in existing macroeconomic studies. However, according to the estimates that use the relationship between the key variables in our model together with climate change scenarios published by the Network for Greening the Financial System (NGFS), the impacts of these shocks could become somewhat larger in the future.