Building Mumbai anew

Land reclamation is like an organ transplant — it requires skill and patience

Mumbai’s space crunch has led to suggestions from some quarters that reclaiming land from the sea should be considered as a possible option. Instances of airports constructed on artificial islands created in the sea are being cited from Hong Kong and Japan. Similar cases of reclamation come from elsewhere in the world too and so reclamation is being touted as a solution to Mumbai’s problems of space for its millions.

However, it needs to be realised that reclaiming land from the sea is a process that goes against nature’s scheme of things, in which the shoreline is maintained as the line of control between the land and the sea. Any attempt to push back the sea by filling up the waterfront with rubble and earth will amount to interfering with nature’s programmed processes — like, erosion at some places and deposition elsewhere. Nature does not brook any such interference and hits back surely even if it is slowly, because the energy earmarked for a particular process has to be spent and if it is obstructed from doing so at one place, it will manage to spend it at another place.

The northern part of the Mahim Bay at Bandra has undergone several phases of reclamation over the years so much so that today a substantial portion of the well-carved-out bay has become land. There is a sea-cliff here with a rocky beach below formed by sea-erosion and the nearest sandy beach is Dadar Chowpatty in the southeastern corner of Mahim Bay. It has been observed in recent years that erosion has set in here leading to reduction in the width of the beach.

There was no erosion here previously and therefore it can be inferred quite logically that the erosion which was operating in the northern part of the Bay, south of Bandra has now got directed to Dadar Chowpatty as a consequence of the recent reclamation. Some of the buildings on the waterfront here also developed cracks, strengthening this inference.
Mumbai as it is today was formed from a cluster of seven islands in the Arabian Sea, the interim portions of the sea having been filled up. But, strictly speaking, this is not so much a ‘reclamation’ per se as it is a ‘restoration’ of submerged areas for residential purposes. The sea between the islands was shallow and the coastal processes did not operate here as they would along an open shoreline. Therefore, strangely for a reclaimed city, it will be difficult to fall back on the Mumbai model to justify a further reclamation exercise.

The most important problem, however, lies in the nature of the seafloor adjacent to the shoreline in Mumbai. The Mumbai coast is believed to have originated due to the West Coast ‘Fault’ which explains the straight configuration of the entire west coast. This ‘fault’ is a vertical plane along which a substantial portion of the land has been displaced down into the sea. Because of this, the seafloor adjacent to the shoreline in Mumbai is a lot steeper and therefore the rock blocks and earth materials dumped on it during reclamation will not be able to settle down.

In fact the same situation obtains all along the west coast and that is why there is absolutely no delta at all anywhere in the west coast in contrast to the east coast which abounds in deltas. Therefore, it is very doubtful whether the rock and earth materials which will be dumped along the Mumbai coast during the reclamation process will stay where they are put down. It is even more unlikely that they will get integrated with the rocks on the sea floor to the extent of growing into a stable landmass good enough for taking up the load of construction — the whole point of this reclamation suggestion. Reclamation is akin to an organ transplant — the extraneous material provided has to be accepted by the host. This may well not happen along the Mumbai shoreline.

Finally, there is the time factor. Reclamation being what it is — a difficult proposition — sufficient time needs to be given to the reclaimed area to get consolidated into a new landmass before any construction activity on this is contemplated.

It is true that in Japan and Hong Kong international airports have sprung up on artificially created islands but these new islands were given quite a few years to get rooted well into the seafloor and attain the required compaction before any other operations began. And still, their performance is continuously monitored, without complacency on the part of the authorities. Only if all these conditions and constraints are kept in mind, can reclamation prove to a long-term solution to Mumbai’s problems. Or else, haste will make waste.

The writer is former professor of geology, at IIT, Bombay.

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