Not solely are Mumbai’s rivers clogged, however the wetlands surrounding them are additionally virtually non-existent, so when the rivers overflow they mechanically result in flooding in close by localities
The primary showers of this 12 months’s monsoon nearly hit Mumbai and India’s monetary capital went underneath. If you’re a Mumbaikar, the query you’d need urgently answered is that this: can Mumbai ever welcome the rains when it does not trigger flooding and produce the utmost metropolis to a standstill? There are key components at play that you must find out about whereas ready for the waters to recede and town to up its drainage sport.
As the first issue behind frequent flooding, one must look no additional than the frenetic tempo of development within the metropolis. Mumbai is in a relentless state of enlargement, laterally and vertically, and large-scale development exercise is a continuing for town.
This impacts flooding in two methods: first, as increasingly more pure area will get transformed right into a built-up space, the pure means of the land to soak up water and forestall it from gathering in a spot is misplaced.
Second, the particles and waste generated by development exercise clog up the drains and nullahs, stopping the run-off water from escaping.
It was a few years again that protests over the Aarey metro shed had rocked Mumbai. Then there’s the coastal street venture that’s anticipated to have critical ecological ramifications.
In keeping with a 2019 report by Kanchan Srivastava and Aditi Tandon for Mongabay, the pattern of reclamation of land that town has been traditionally a witness to has additionally performed a component in choking it up when heavy rainfall strikes.
The land space of town swelled by nearly 50 sq km in lower than three a long time since 1991, the report stated. However the true difficulty is, after all, that many of the reclaimed land is actually low mendacity and, therefore, flood-prone. The common peak from sea degree alongside some stretches is lower than one metre, the report stated.
It does not assist when torrential downpours are accompanied by excessive tides.
As soon as these would have finished the work of stormwater drains, however unlawful development, encroaching, and air pollution have turned Mumbai’s rivers into shadows of their former selves. In keeping with the Mongabay report, “one of many main rivers, Mithi, has develop into a veritable sewer, choked with home and
industrial waste and overflows each monsoon”.
The scenario is comparable within the different rivers like Dahisar, Poisar and Oshiwara. Not solely that, the wetlands alongside these rivers are actually virtually non-existent, which implies that there isn’t any buffer between the waterline and adjoining localities. When the rivers overflow, they mechanically result in flooding in such localities.
A 2019 report by the Comptroller and Auditor Basic (CAG) on the flood preparedness of Mumbai had pointed to “main deficiencies” with the drainage system. One of many components it had flagged was the delay in upgrades to metropolis’s floodwater drainage system.
The Brihanmumbai Storm Water Disposal System, or BRIMSTOWAD venture, was conceptualised in 1993 however was reportedly taken up solely after the devastating 2005 floods that hit Mumbai. The works to finish the venture are stated to be ongoing even because the CAG had highlighted critical points within the report. Amongst these have been heavy silting of the drains and obstructions brought on by development and dumping of waste.
An added fear, the report stated, was that the most important shops to flush the water away have been all beneath sea degree, which implies that on excessive tide or heavy rainfall days, these drains are incapable of clearing out the water.
The report had additionally famous that the capability of the drains was to take care of rainfall of the extent of 25 mm an hour. However the actuality is that as of 2019, work was nonetheless ongoing to extend that capability for rainfall of fifty mm per hour.
Alleged deforestation of coastal mangrove belts has additionally been cited by environmentalists as an enormous contributor to frequent flooding. The Mongabay report had cited analysis by Mumbai-based environmental group Vanashakti that town had “misplaced 40 p.c of its mangrove forest cowl between the early Nineties and 2005”.
Though that estimate was contradicted by the federal government’s State of Forest Report 2017 that their unfold had truly elevated since 2015, activists say that the current mangrove cowl will not be satisfactory for a metropolis that is without doubt one of the wettest of India’s metros.