Spike in flash floods raises concern of ‘micro’ climate changes in Himachal

Updated - September 05, 2023 01:13 am IST

Published - September 05, 2023 01:12 am IST - CHANDIGARH

The number of flash flood events in Himachal Pradesh has surged dangerously over the past few years, killing hundreds of people, damaging critical infrastructure, and raising concern about the ecologically fragile Himalayan region.

Government data show there have been 72 flash floods in the State from the start of the monsoon season on June 24 until September 4. This compares with 10 incidents of flash floods in the 2020 monsoon season, 16 in 2021 and 75 last year, as per data from the State’s Disaster Management Authority. This year’s tally could rise further as the monsoon season is yet to end. In Himachal Pradesh, the rainy season extends from June-end till mid-September.

Flash floods, a highly localised and sudden phenomena, are normally a result of torrential downpour and are caused typically within six hours of the occurrence of rainfall. This often catches people downstream off guard.

Contributing factors

Environmentalists and weather experts believe that rampant unscientific and ill-conceived construction activities over the years have made the hill State more vulnerable to natural disasters such as flash floods and cloudbursts. Large-scale tree felling, excavation for hydroelectric projects, tunnels and roads, and construction of huge buildings were contributing factors for changing climate patterns at the ‘micro-level’ in the region.

“Rapid unscientific urbanisation and an increase in vehicular traffic are also factors bringing micro-climatic changes,” says Vinod Kumar, an assistant professor at Vallabh Government College at Mandi. “The growing number of flash floods is a warning sign for the fragile Himalayas,” adds Mr. Kumar, who has published a paper on flash floods in Himachal Pradesh in the Journal of Geography and Natural Disasters.

Surender Paul, director of the India Meteorological Department (IMD) at Shimla, tells The Hindu that “climate inconsistency” has increased in Himachal Pradesh over the past decade. “The weather pattern is changing invariably and a shift in the pattern of precipitation is visible. On one hand, the average precipitation tendency has been decreasing, especially the monsoon rains. But on the other hand, the occurrences of erratic and sudden spells of rain or flash floods have increased. The gradual rise in temperature and warming could be a reason behind this,” he says.

Although a global phenomenon, climate change can’t be seen in isolation. “Modification of the physical environment by humans – such as building dams and reservoirs to store and divert river water, deforestation, land degradation, desertification, excavation for development activities – impact local weather conditions,” he says. “Flash flooding is a critical environmental concern faced by the State right now, and their escalation is through atmospheric as well as man-induced interferences,” he adds.

Anand Sagar, professor and chairman at the Department of Environmental Science of Himachal Pradesh University, says that past trends show reduced snowfall and rising temperatures in the State. This increases the moisture and holding capacity of water vapours in the atmosphere, especially during monsoons. “Along with other reasons, it could cause sudden heavy rainfall or cloudburst, triggering flash floods,” he says.

Developmental activities, he adds, do not damage the ecology if the work is done in a scientific manner. “However, if it’s done in an unscientific manner, which appears to be the case in the State, then the consequences would be disastrous. Micro-climate change is happening and indiscriminate and unscientific activities would only aggravate the situation in the Himalayas,” he warns.

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