Flash floods are sudden, usually unexpected surges in water levels that typically occur during or immediately after an intense spell of rain. These are highly localized events of short duration, with a very high peak flow, usually occurring within six hours of the rainfall’s start.
The flood situation can be exacerbated by blocked drainage lines or obstructions hindering the natural water flow. The leading cause of flash floods is heavy rainfall associated with severe thunderstorms, hurricanes, or tropical storms. Alternatively, they could result from melting ice or snow flowing over ice sheets or snowfields. Dam or levee breaks, and mudslides (or debris flows) can also trigger flash floods.
In areas near to or on volcanoes, flash floods have also been reported following eruptions, due to glaciers being melted by the intense heat. Several factors determine the rapidity of flash flooding, including the rainfall intensity, distribution, and location, as well as land use, topography, vegetation type and density, soil type, and soil water content.
Insights into Cloudbursts: What They Are and When They Occur
Cloudbursts are weather phenomena characterized by short-duration, intense rainfall over a small area. They occur when unexpected precipitation exceeds 100mm/h over a geographical region of approximately 20-30 square kilometers.
In the Indian Subcontinent, cloudbursts generally occur when a monsoon cloud drifts northwards from the Bay of Bengal or the Arabian Sea across the plains, then onto the Himalayas. Such movement sometimes results in heavy rains of up to 75 millimeters per hour.
Cloudbursts occur when the relative humidity and cloud cover reach maximum levels due to low temperature and slow winds. The high quantity of cloud condenses at an incredibly fast rate, resulting in a cloudburst. As temperatures increase, the atmosphere can hold more moisture, leading to heavy rainfall for a short duration – often half an hour to one hour – resulting in flash floods in mountainous areas and urban floods in cities.
How Cloudbursts Differ from Rainfall
While rain refers to condensed water falling from a cloud, a cloudburst is a heavy, sudden rainstorm. Rainfall over 100mm per hour is classified as a cloudburst. They occur quite unexpectedly, abruptly, and are usually drenching.
Consequences of Cloudbursts
Cloudbursts carry several consequences, including flash floods, landslides, mudflows, and land cavings.
Why Cloudbursts Occur in Hilly Areas like Amarnath
In hilly regions, such as Amarnath, the upward movement of warm air currents sometimes prevents saturated clouds ready to condense into rain from producing rainfall. Instead, raindrops are carried upwards by the air current. New drops form, and existing ones increase in size. When the raindrops get too heavy for the cloud to bear, they fall down together in a quick flash. A 2020 study examining the meteorological factors behind the cloudburst over the Kedarnath region found that during a cloudburst, the relative humidity and cloud cover were at maximum levels, with low temperatures and slow winds.
About Amarnath Temple and Flash Floods
Amarnath Temple is a revered Hindu shrine located in Jammu and Kashmir, India. The temple resides at an altitude of 3,888 m, approximately 100 km from Srinagar, the summer capital of Jammu and Kashmir. Access to it is through the town of Pahalgam. The shrine is a crucial part of Hinduism, which saw the resumption of the Amarnath yatra after three years of break this year. There are two routes to reach the cave shrine via Pahalgam in the south and Sonamarg in central Kashmir.
Recently, flash floods in the region caused landslips near the Baltal base camp in Central Kashmir’s Ganderbal area. The tragedy led to at least 13 deaths, primarily Amarnath pilgrims, and several others went missing in flash floods.
Last Modified: February 15, 2024