Impacts of future urbanization scenarios on precipitation patterns over the metropolitan area of São Paulo (MASP): Insights from numerical simulation

Abstract

Several studies have shown that the urbanization process has an impact on precipitation pattern, especially leading to an enhancement. Urban centers are expected to expand following the prospects of urban population increase. Understanding the possible impacts of future urbanization on precipitation becomes essential to aid in the development of mitigation plans and to reduce population vulnerability. The Metropolitan Area of São Paulo (MASP) is, mainly during summer, affected by heavy rain episodes with serious economic and social impacts. Here, the effects of three future scenarios on a storm event over the MASP are analyzed using numerical simulation. The scenarios are: LULC change, anthropogenic heat increase and a combination of both for 2050. Our results showed that rainfall rate is more intense in all future scenarios resulting in an increase on total precipitation. Still, urban expansion increased precipitation coverage area, while the increase in anthropogenic heat fluxes had a higher contribution on the intensity of precipitation. Low-level convergence and consequent upward motion were enhanced on future scenarios intensifying convection and consequent precipitation. Increasing anthropogenic heat flux also led to an increase in instability further contributing to convective enhancement. According to our conclusions, the scenario with both LULC change and anthropogenic heat increase is the most problematic one for the MASP with the most intense rainfall rates and an increase in 16 % in the area affected by precipitation.