Rain Gardens and Monsoon Flood Management in Mumbai

Abstract

Mumbai experiences 2,200–2,800 mm of annual rainfall, much of it concentrated in a few monsoon weeks, producing chronic flooding in low-lying neighbourhoods such as Hindmata Junction. At the same time, the Mumbai Coastal Road project is creating roughly 130 acres of new reclaimed parkland along the city’s western shore. This paper asks how much practical potential rain-garden systems have to reduce localised waterlogging in Mumbai’s monsoon climate, and how that potential differs between dense inland bowls and newly reclaimed coastal open spaces. The study adopts an identification-and-description strategy using secondary data: Indian Meteorological Department rainfall records, Municipal Corporation of Greater Mumbai drainage reports, media coverage of recent flood events, and international literature on rain-garden performance in tropical cities. Simple volume estimates and typology-based reasoning are used to compare feasible rain-garden configurations at Hindmata and along the Coastal Road parks. Results show that at Hindmata, extreme inflows from a ~2 km² catchment (on the order of 150,000–170,000 m³ per hour during cloudbursts) dwarf the storage that micro-scale rain-garden typologies could realistically provide, limiting their role to mitigating kerb-side ponding and improving water quality. Along the Coastal Road, by contrast, the combination of smaller contributing catchments and contiguous programmable parkland allows park-integrated bioretention basins and bioswale corridors to intercept a meaningful fraction of runoff. The paper argues that urban form is a decisive filter for the feasible role of rain gardens in dense coastal megacities, with implications for how Mumbai and similar cities deploy green infrastructure for monsoon resilience.