Mumbai Has Lost 36% of Its Mangroves Since 1973

By Marcus Bennett

India's mangrove forests deliver more than US$65 billion in annual flood-protection benefits globally, according to modeling by Pelayo Menéndez published in 2020. Remove those forests, the model suggested, and an additional 15 million people would flood each year. The figures are global estimates, not site predictions. They still fix the scale of what coastal development in India is trading away.

What does the forest actually do to a surge?

The numbers are concrete. A 2019 study modeled Cyclone Sidr along the Bangladesh coast across different mangrove widths and planting densities. Flow velocity fell by 29–92%. Surge height dropped by 4–16.5 centimeters. Results varied with forest width, vegetation density, and bathymetry.

That mechanism matters to engineers. Roots, trunks, and branches obstruct moving water, and the researchers found potential for mangroves to reduce erosion and damage to coastal embankments. In Bangladesh, where embankments protect settlements from cyclones, lower flow velocities could limit erosion at the base of those structures and reduce breaching risk. The study does not claim mangroves replace embankments. It shows that the landscape in front of a defense changes the water that reaches it.

How much has Mumbai lost?

Geographer Eric Vaz examined the Mumbai Metropolitan Region in 2014. His analysis reported that 36% of the region's mangrove system had been lost to urban land since 1973. A 2025 study of Greater Mumbai mapped cover from 1994 to 2024 and recorded a decline from 71.8 to 68.99 square kilometres. The two datasets cover different periods and boundaries, and should not be read as one continuous measurement.

Mumbai concentrates the conflict. Mangroves occupy creek and estuary edges alongside transport corridors, housing, industrial land, and reclaimed territory. Development at the forest edge narrows the space the forest needs and can interrupt the tidal channels that move water and sediment through it.

Does restoration money buy a functioning forest?

Between 2012 and 2022, more than US$5 million went into Mumbai's mangrove restoration programs. Adam Shaham evaluated 25 restoration sites using satellite imagery and time-series analysis. The method examines outcomes beyond dollars spent or trees planted.

The catch is measurement. Vegetation cover is one indicator. It does not establish whether tidal flows, sediment processes, and the hydrological conditions a functioning forest requires have returned. In Mumbai, where tidal landscapes have been heavily modified, more mapped green does not prove recovery.

What changes for architects and planners?

The evidence points to the coastal section as the working tool. A section from open water to inhabited land shows tidal channels, vegetation, sediment, embankments, roads, and settlements in one drawing. It identifies where the forest has room to grow, where water moves toward a defense, and where people remain exposed. Structural design still turns on flood levels, loads, and ground conditions. Those are only part of the spatial arrangement that determines exposure.

Odisha's Bhitarkanika landscape makes the stakes legible. In a 2005 study, Ruchi Badola and S. A. Hussain compared cyclone damage from the 1999 super cyclone across three villages, assessing losses to houses, livestock, fisheries, and trees alongside flood depth and duration. In 2022, stakeholder-informed land-use scenarios for the same landscape tracked carbon storage, sediment retention, and nutrient export under different arrangements — evidence that one development decision redistributes vegetation, water, and sediment beyond its boundary.

Parcel-by-parcel planning misses these connections when the coast is treated as separate sites. Mangroves cannot eliminate risk or substitute for engineered defenses everywhere. Their effect depends on forest condition, local hydrology, and the structures behind them, while settlements continue to expand into the same territory. Coastal planning that reads the forest, the embankment, and the street as one section will price flood exposure more honestly than one that draws them separately.