Monday, 31 January 2022

Flooding and landslides kill at least 21 people in São Paulo State, Brazil.

Twenty one people are now known to have died and several more are missing amid heavy rains that have battered the Brazilian state of São Paulo since Friday 28 January 2022. Over 500 000 people have been displaced from their homes by flooding events, and at least 11 to have been killed in a series of landslides triggered by the rains. 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.

Flooding in the municipality of Franco da Rocha in São Paulo State, Brazil, on Sunday 30 January 2022. CNN.

Southern Brazil has a rainy season that lasts from Ocotober to March, with peak rains from mid-November to mid-January, however, this year's rains have been exceptionally strong. Brazil has suffered a string of flood-related disasters in recent years, most notably in 2011, when over 800 people died. The country has a rapidly growing population, with little effective urban planning, which has led to sprawling urban developments springing up with little thought to natural hazards, and in particular poorer neighbourhoods often expanding up unstable hillsides, with the result that when floods occur (which is not unusual) communities are often quickly overwhelmed. This years exceptional rains have led to more widespread flooding, which may also persist for longer, and there is a distinct danger that without determined action the death toll may exceed that of 2011. Such events are becoming increasingly common in Brazil, something which many climatologists are citing as direct evidence of global warming.

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