19 July 2021
Mumbai: at least 29 fatalities in monsoon landslides
As the South Asian summer monsoon continues to intensify, the city of Mumbai in India has once again been affected by serious landslides in the last 24 hours. As is often that case, the current picture is quite confused, but details of two large events are emerging. The clearest picture at the time of writing is in an article in the Hindustan Times.
First, at 1 am on 19 July 2021 a retaining wall collapsed in New Bharat Nagar in the Chembur suburb of Mumbai, burying about five houses. In total it is believed that 19 people were killed, of whom at least four were children. At least five more people were injured.
A few hours later, at about 3 am, a further landslide occurred at Surya Nagar in the suburb of Vikhroli, burying at least seven houses. Reports indicated that ten people were killed, of whom three were children. The image below shows the aftermath of this landslide:-
Note that these landslides occurred in densely populated suburbs with informal houses constructed with a very high density. The vulnerability of such areas to slope failures is high.
News reports suggest that this was the second of two large rainfall events this week. On Friday 253 mm of rain fell, followed 235 mm of rainfall in four hours on Sunday. Reports also suggest that there had not been a warning for a heavy rainfall event on Sunday.
The Deccan Herald has a good article about the landslide problem in Mumbai, which notes that at least 290 people have been killed by slope failures since 1992. Many inhabited locations are prone to landslides, and action has been urged to relocate the most vulnerable and to engineer solutions in other spots. However, as usual I note that whilst relocation is often desirable and has been successful elsewhere, poorly planned displacement of people can make them vulnerable to a range of other (usually social) hazards, negating the benefits.