The Annual Deluge in Mumbai

Flooding of Mumbai roads and submerging of rail tracks under several feet of water seems to have become an annual feature. Life comes to a standstill for a city reputed to be always on the move. Ground floor residences in low lying areas have water entering the living rooms and furniture and household belongings can be seen to float in these indoor pools.

Is it that Mumbai has started having more precipitation in recent years? It seems that as the city has grown, open areas like parks which used to provide buffer holding capacity for storm water have shrunk and as the drainage system carrying capacity remains constant, water overflows onto the streets and railway tracks paralysing the city traffic.

Clearly the capacity of the drainage system must grow as the open areas shrink. There can be no argument about this execept that open areas can be prevented from shrinking by going vertical which is another story by itself. For the moment a self sustaining economic model which would improve drainage capacity with time could be explored. This would be pertinent to any urban settlement not only a megapolis like Mumbai.

Let us imagine a commercial organization which runs a network of storm water drains in any city through a concession agreement. All houses, societies, institutions would subscribe to connect to the drainage network with tarrifs probably based on plot areas. In case of flats on a plot, the tarrif could be equitably divided as the plot is considered an undivided asset.

Municipalities which own the roads would also be required to subscribe and connect to the drainage network through roadside drains which would would receive surface rain water runoff from properly cambered roads. This would ensure zero water logging and much longer life for road surfaces and therefore significantly lower maintenance.

The drainage company's tarrifs would be regulated like all utilities based on cost plus formulae as is customary for services where free market competition is technically not feasible. The service level agreement guaranteed by the drainage utility would promise instant evacuation whatever the level of precipitation including cloudbursts and hurricanes.

As a commercial organization, the drainage company would soon realize that its network could be hired out for many other applications. All Power, Water, Telecom, Cooking Gas, TV Cabling and other Piping could use the very large caliber drainage network for riding their networks onto and would make the constant modifications, alterations and augmentations very simple indeed. No roads would have to be constantly dug up, no cables would get snapped and the repairs and maintenance of utilities piping, cabling, connectors etc. would be very convenient if and when required.

Since storm water drainage is a universal feature, it can be exploited as a critical piece of urban infrastructure. Indeed it would provide the foundation on which most of the other utilities would ride. Municipalities could then even ban overhead pole based wiring and cabling and the question of invoking the right of way for roads crossing etc. itself would go away. With everything out of sight and necessarily underground, the cities would give a much neater look too as there would be no poles to clandestinely hang small hoarding on.

It would be important to keep the drainage network strictly separate from the sewage system network as the design constraints are totally different. Sewage system carries a lot of biological and chemical load but the peak volumes (for which the capacities are designed) would be a tiny fraction of the Drainage network. There is really no practical need served in polluting an extremely large infrastructure by injecting a small steady amount of sewage into it.

As a matter of convenience, if the sewage system is kept separate, small and confined, it would surely be possible to treat it much more economically and effectively. May be the storm water drainage company could float a subsidiary to manage sewage.

A small flood in Mumbai can trigger a lot of productive thought...