Explained: Why townships in Thane district witnessed flooding todayhttps://indianexpress.com/article/explained/mumbai-rains-thane-rivers-flooding-5856451/

Explained: Why townships in Thane district witnessed flooding today

If a Mithi river in spate caused much of the havoc on July 26, 2005, when a cloudburst led to 944 mm of rain in Mumbai within a span of 24 hours, likewise, the overflowing Ulhas river is responsible for parts of Ulhasnagar being severely inundated on Friday evening and Saturday.

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Bhiwandi and Shahapur received 185 mm and 195 mm of rain, respectively.

In the far suburbs of Mumbai city, the townships of Kalyan, Ulhasnagar, Murbad and Ambarnath received over 200 mm rain for 24 hours until this morning. Murbad, which includes rural areas, received 332 mm on average, within 24 hours, while Ulhasnagar received 296 mm and Ambarnath received 280.10 mm. Bhiwandi and Shahapur received 185 mm and 195 mm of rain, respectively.

Why have townships in the Thane district witnessed flooding today?

Some of these townships are located alongside the Kalu, Ulhas, Waldhuni and Bhatsa rivers that shimmy down right through Mumbai’s outback area, the Mumbai Metropolitan Region, well over ten times Mumbai’s geographical area. These rivers run through some thickly populated areas and the financial capital’s dormitories of Ulhasnagar, Titwala, Badlapur, Vithalwadi, Ambarnath, etc.

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If a Mithi river in spate caused much of the havoc on July 26, 2005, when a cloudburst led to 944 mm of rain in Mumbai within a span of 24 hours, likewise, the overflowing Ulhas river is responsible for parts of Ulhasnagar being severely inundated on Friday evening and Saturday.

The Ulhas river is one of the more polluted rivers in the Mumbai Metropolitan Region and is the subject of various petitions pertaining to industrial effluents in the National Green Tribunal. “There are years of neglect and pollution which has led to the water pathways being clogged, be it natural or man-made. There is nowhere the water could go and that is why it’s overflowing and reaching houses,” said river activist Janak Daftary. He added that regular cleaning of the Ulhas river doesn’t take place, thereby compounding the problem of encroachments.

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According to Ulhasnagar corporator Mira Tonde, who represents the Kurla camp area, cleaning had actually taken place. “The river was cleaned but that’s not where the problems lie. The level of encroachment has made it difficult for us to reach smaller nullahs and channels. People cast their waste into the drains, directly choking them up even after we clean them. This has led to the situation today,” she said.

Are polluted rivers the only cause for these regions flooding?

Titwala, Asangaon and nearby areas also witnessed flooding due to the overflowing Modaksagar and Tansa reservoirs, which serve Mumbai’s drinking water needs. Overflow from these reservoirs again flows through rivers that run through the now thickly-populated regions.

Approximately, 13 west-flowing rivers and their 21 tributaries are important natural floodwater drainage systems for the region. Multiple dams on the west-flowing rivers are in various stages of construction or planning, including the Kalu, Shai, Gargai, Pinjal, Poshir and Barvi dams. Nearly 30,000 tribals are expected to be displaced by these.

While on the one hand, some of these rivers are encroached upon and in poor condition owing to industrial and municipal waste, the densification of these areas alongside the construction of more dams in the region to slake an ever-growing thirst of the Mumbai region makes these outback municipalities more prone to flooding.

What needs to be done to make these towns safe from flooding?

The population of the ‘Rest of MMR’, i.e, excluding Mumbai, has grown from 18 lakh in 1971 to 106 lakh in the 2011 census. This estimate errs on the side of caution — for not only is the Census data now almost eight years old but also because this does not account for more recent additions of peri-urban areas into what constitutes the MMR.

The decadal growth rate of population for the city of Mumbai between 2001 and 2011 was recorded at 4 per cent while for the rest of the MMR, it was nearly 55 per cent. There are also large industrial belts in the MMR — those across the TTC (Trans-Thane Creek) area, Taloja, Waghle Estate, Dombivali, Ambernath, Bhiwandi, etc. This multifold growth of population has not been met with commensurate growth in municipal amenities — a 2015 survey by the MMRDA found only 59 per cent of the waste water treated, none of the urban local bodies matched the service benchmarks set for collection of the waste water.

An overhaul of municipal amenities in these regions, planned in a holistic way that takes into account the likely floodwaters of the new reservoirs and dams being constructed in the region, is essential for flood-proofing this region.