5 August 2021
Understanding the recent monsoon landslides in Maharashtra, India
Last month, heavy rainfall in the Maharashtra area of India triggered a number of deadly landslides. The most serious of these occurred at Taliye village, where at least 53 people, and possibly as many as 84 people, were killed. However, this was not the only substantial landslide; there were at least another six fatal landslides, which took an additional 50 lives.
My friends at South Asia Network on Dams, Rivers and People (sandrp.in) have done a heroic job in collating information about these landslides, their locations and impacts. I have used their information to produce a quick Google Earth map of the landslide locations:
I have included two significant non-fatal landslides as well. It is interesting to compare the landslides to a map of the rainfall. The map below is a 3 day rainfall total for the period ending 24 July 2021 (the Taliye landslide occurred on 22 July 2021), from the NASA Global Precipitation Measurement mission:
The cluster of high rainfall totals exactly where the landslides were triggered is clear. The map below (from Researchgate) shows the topography of Maharashtra:
The map shows that there is higher elevation ridge running approximately parallel to the coastline. It is clear that the high rainfall totals reflect this ridge (presumably due to an orographic effect), and of course it also provides the topography for the landslides. The main landslide cluster is to the southeast of Mumbai (Bombay).
But why were there so many landslides? The answer may well lie, at least in part, in degradation of the environment. Removal of natural vegetation, cutting of slopes, quarrying and road building are taking a huge till across the upland areas of India (and indeed across the hilly parts of much of South Asia). As usual, in the aftermath of monsoon landslide disasters there is discussion about warning systems and suchlike (which in general have a very patchy success rate in rural settings in less developed countries). Although they can and do have a role, this is to miss the salient point, which is that we need to work on preventing increases in susceptibility as a priority, mainly through better management of slopes.
Climate change is going to exacerbate these problems at pace, as will continued damage to slopes. If we are to reduce these disasters, we need manage the slopes properly.
Many thanks to my friends at the South Asia Network on Dams, Rivers and People, and in particular Parineeta Deshpande-Dandekar, for help with the data in this post.