Torrential monsoon rains over the last seven days have reached life-threatening levels for communities south of the Himalayas from Nepal to Bhutan and northern India to Bangladesh.

Severe floods and landslides have wrought havoc. Already across the affected region communities have faced tragedy, including: loss of life; thousands of homes submerged; extensive crop damage; as well as collapsed bridges and blocked roads.

Further heavy rain is forecast over the next few days and this will extend the zone of flooding downstream to communities lining those major rivers which flow from the Himalayas.

Nick Silkstone is a Met Office forecaster working in the Global Guidance Unit. He said: “The region between the Himalayas and the Bay of Bengal is bisected by some of the world’s great rivers, such as the Brahmaputra and the Ganges, which drain the region normally taking water safely to the sea.

“Even though these are some of the world’s mightiest rivers the forecasts suggest even these giants are going to struggle with the amount of pressure these systems are currently facing.

“Global flooding indicators, such as GLOFAS, are indicating high probabilities of river flows that are only anticipated once every two decades in many of the region’s major rivers, giving an early warning of a significant event to come in the next week.”

There are already reports of extensive loss of farmland due to the flooding, and agencies are reporting waterborne diseases proliferating in flooded areas.

The monsoon is a natural part of south Asia’s weather, but this year rainfall in some areas has been over four times greater, when compared with the average between 1981–2010.

Clare Nasir is a weather presenter and meteorologist with the Met Office. She said: “The monsoon brings life-giving rains to the region, but the conditions in some years can be very cruel.  Extensive rainfall can be more concentrated in some parts than others. This year, the north region has received much more rain than other parts of India.”

With further rain forecast this coming week and a lag time from last week’s rain reaching communities downstream, the risk of extensive flooding continues.