cloudburst is an enormous amount of precipitation in a short period of time, sometimes accompanied by hail and thunder, capable of creating flood conditions.
Cloudbursts can quickly dump large amounts of water. The recent disaster in Dharali in Uttarakhand’s Uttarkashi district, attributed to a ‘cloudburst’ by state officials due to extremely heavy rainfall from August 3 to 5, led to significant loss of life, livelihood, and property. Some parts of the district reported nearly 30 cm of rainfall over a single day due to the monsoon and its active phase over North India.
The India Meteorological Department (IMD) defines a cloudburst as a large volume of rain of at least 10 centimeters in an hour over 10 square kilometers. However, due to the lack of weather radars at high altitudes, the IMD is incapable of computing such data.
It is possible that continuous heavy rain over 48 hours loosened the soil and, combined with the craggy terrain, unleashed large volumes of silt and water. Whether the event was sudden or a result of a gradual build-up may seem academic given the devastation.
Categorizing the event as a ‘cloudburst’ allows state authorities to claim helplessness, projecting it as a freak phenomenon that elicits social media commiseration and a pre-defined token sum as disbursement.
However, recent past events show that extreme rainfall occurrences are not outliers. Climate change has increased the probability of such events, and infrastructure projects in the hills with resulting debris act as latent explosives triggered by rainfall.
Cloudbursts in and around the southern rim of the Indian Himalayas are elusive in terms of position and time of occurrence. Most reported cloudbursts are in the interior of the Himalayas, limiting observation.
These events are mostly reported after their impact in terms of loss to life and property is experienced in downstream habitats. They are often associated with flash floods due to torrential precipitation. The principal understanding of a cloudburst is a sudden heavy deluge of precipitation in a very short time over a small area. Beyond the IMD definition of >100 mm/h precipitation over 20-30 km², little is known about these events, and there are few studies on understanding them.
Following relief operations, the State government must review debris and silt accumulation at critical points to buffer the inevitable damage from climate change.
With climate change increasing extreme rainfall events, understanding and preparing for such phenomena are crucial to mitigate impacts in vulnerable regions like the Indian Himalayas.
