Green Roofs to mitigate the urban extreme precipitation events? An experimental study over Mumbai, India
Abstract
Green Roofs are one of the measures to mitigate the Urban Heat Island (UHI) effects. The cooling effects of green roofs are well studied in the literature. Green roofs can change temperatures and modify humidity. Here we postulate that the change in microenvironment due to green roofing may also have a potential to modify mesoscale convection and hence the intensity, distribution and related aspects of heavy (extreme) precipitation. We first develop and present a conceptual thought experiment as to possible pathways of mesoscale convection changes amidst green infrastructure changes. We then evaluate the postulation using the detailed urban WRF modeling system by taking the example of an extreme rainfall case that affected Mumbai city on 29 August 2017. The event while labelled 'extreme' is typical of the heavy rain events the city has been experiencing in recent years. The event was simulated for different green roof scenarios, viz. 10%, 25%, 50%, as well as 75%, and 100% green roof over the urban area. The green roof simulations are compared with respect to 'no green roof' simulation (control run). After this a prior green roof specification experiment, a multi-criteria Monte Carlo experiment was undertaken to assess the possible location and magnitude of green roofing that will be required to have 1, 2, and 3 deg C changes for the city. Using the resulting green roof distribution WRF results were regenerated to see whether the temperature effects are similarly obtained when using coupled analysis. Initial results suggest green roofing may further increase the intensity of heavy rainfall and this leads to an interesting question regarding what mitigation pathway should a city consider- when green infrastructure for temperature regulation may cause possibly higher flood potential.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC21I1370P
- Keywords:
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- 0493 Urban systems;
- BIOGEOSCIENCES;
- 0231 Impacts of climate change: agricultural health;
- GEOHEALTH;
- 1622 Earth system modeling;
- GLOBAL CHANGE;
- 1630 Impacts of global change;
- GLOBAL CHANGE