Sunday 28 June 2020

Landslide kills one in Guwahati, India.

A woman has died after her house was destroyed by a landslide in the Kharguli area of the city of Guwahati in Assam State, India, on Sunday 28 June 2020. Priyanka Boro, 21, described as a talented performing artist specialising in classical, folk, and Bihu dancing, is believed to have died instantly in the event, which happened after days of heavy rain in the area associated with the Indian Monsoon Season. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

Talented dancer Priyanka Boro, 21, of Guwahati, Assam, and the aftermath of the landslide which killed her on 28 June 2020. Northeast Now.

Guwahati is notoriously prone to landslides, particularly during the summer monsoon season, in part due to the hilly nature of the city, but largely due to the largely unplanned nature of many of the cities poorer districts, with many dwellings erected illegally without any formal planning permission, often on slopes where a thin layer of laterite clay covers a friable, sandy soil, which is prone to collapsing downslope when disturbed.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. 

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

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