23 September 2019

Kerala – the hungry rains

Posted by Dave Petley

Kerala – the hungry rains

The Indian financial newspaper Mint has published an article last week, The Hungry Rains, which examined the impact of the 2019 monsoon on Kerala in western India.  Kerala is the main coastal state lying along the  southwest part of the country. The main take home message from the article is that Kerala is enduring an ecological crisis that is making the state exceptionally vulnerable to the effects of the monsoon, resulting in extensive destruction and high levels of economic loss.  Kerala has suffered devastating losses two years in a row, with the exemplar being the Kavalappara landslide in August, which killed about 60 people.

The Mint argues that poor land use management lies behind many of the problems in Kerala:

“A journey through Kerala shows it’s not just about the weather. Experts from the Kerala State Disaster Management Authority spent the first week of September studying what led to the mudslide that wiped out Kavalappara. Their findings have yet to be made public but a person privy to them says, on condition of anonymity, that apart from the heavy rains, unscientific cultivation of rubber across the hilltop is to blame. The strength of the soil, its ability to resist deformation and lateral motion, has been destroyed by the rubber estates, he says. In other parts of the state, which saw heavy inundation and deadly landslides, they found a clear correlation between the damage and human activities such as quarrying or encroachment of riverbeds. People know about the changes but are not aware of the dangers.”

The vulnerability of India to landslides is fascinating.  Whilst the focus is (correctly) often on the Himalayan Arc, there are also substantial challenges in the west of the country.  The map below shows the rainfall-induced landslide susceptibility for India.  I have created this map from the NASA landslide susceptibility dataset from Dalia Kirschbaum and Thomas Stanley:-

Landslide susceptibility in India

Landslide susceptibility in India, from the NASA landslide susceptibility dataset. High susceptibility is indicated by light colours. Kerala lies along the southwest coast.


And this map shows the distribution of fatal landslides in India from 2004 to 2016, as per the work that I have undertaken with Melanie Froude. The cluster of landslides in western India is clear:-

Fatal landslides in South Asia, 20014 to 2016

Fatal landslides in South Asia, 20014 to 2016. Note the cluster in Kerala.


The summer monsoon in India consists of air drawn from the seas to the southwest of the country, meaning that the coastal areas suffer from high levels of rainfall.  This is the seasonal (monsoon) rainfall map for 2019, from Monsoon Online:-

The seasonal rainfall map for India for the 2019 monsoon

The seasonal rainfall map for India for the 2019 monsoon. Image from Monsoon Online.


Note the very high level of expected rainfall across western India (the “normal” map in the centre), and the exceptional positive anomaly in 2019 (the “departure” map on the right). Thus, Kerala would be expected to have very high levels of rainfall, but this year the total received was significantly higher than average.

The Mint article considers the changes that are needed to try to manage the hazard:

What is the solution? A serious effort must begin with addressing the elephant in the room—how land is governed, says V. Venu, chief executive of the Rebuild Kerala Initiative, a special purpose vehicle floated by the government to rebuild the state after the back-to-back floods and prevent future destruction. “Today’s legal framework practically lets you build pretty much whatever you want, a resort or a house or a commercial building. They have a few stupid restrictions. And, if you fulfil those, for everything else you will get a licence,” he says.

Sadly, at present there is little prospect of meaningful change, so the losses are likely to mount in the years ahead.