The May 2022 landslide cluster at Dima Hasao district in Assam, India

In the period between 11 and 18 May 2022 Dima Hasao district in Assam, India was badly affected by a period of exceptional early monsoon rainfall.  The impact of multiple landslides was widely reported, including some remarkable images of the burial of trains at New Haflong railway station.  Nezine has an excellent set of images of the aftermath by Anup Biswas:-

Trains buried by landslides at New Haflong station on 14 May 2022. Image by Anup Biswas via nezine.com.

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An article just published in the journal Landslides (Roy et al. 2022) provides a very useful initial analysis of this event.  The authors have used satellite imagery to map the landslides.  In total they have identified 5,178 landslides triggered by this rainfall event.  This is their map of this remarkable landslide cluster:-

The distribution of landslides triggered by heavy rainfall in May 2022 in the Dima Hsao district of India, together with landslides from 2014 and 2017. Map by Roy et al. (2022).

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New Haflong Station is located at 25.147, 93.033.  The rainfall event that triggered the landslides is quite interesting.  In May 2022 Dima Hasao district received 540 mm of rainfall, based on satellite data analysis by Roy et al. (2022), including 156 mm on 11 May.  The map above shows remarkable clustering of landslides, implying that this area suffered particularly intense precipitation that might not have been captured by the satellite data.

At New Haflong Station itself, Roy et al. (2022) have identified multiple landslides on the valley walls that coalesced to form channelised debris flows.  Their simulations indicate peak flow velocities of 42 m/sec and simulated maximum flow depths of about 8 metres.  These are exceptionally high values.

There is clearly an urgent need to address the vulnerability of New Haflong Station to landslides.

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Reference

Roy, P., Martha, T.R., Vinod Kumar, K. et al. 2022. Cluster landslides and associated damage in the Dima Hasao district of Assam, India due to heavy rainfall in May 2022. Landslides. https://doi.org/10.1007/s10346-022-01977-6