Snow cover in Himachal down by 12.9% this year, study shows
The winter precipitation was mapped in all basins using the AWiFS satellite data having a spatial resolution of 56 m
Snow cover across the Himalayan region of the state came down 12.9% in 2023-24 compared to the previous year, a study conducted by the State Centre on Climate Change of Himachal Pradesh Council for Science, Technology and Environment (HIMCOSTE), Shimla, has shown.
The state receives winter precipitation in the form of snow at higher altitudes and around one-third of the total geographical area remains blanketed under thick snow cover during the winter season.
Most major rivers like Chenab, Beas, Parvati, Baspa, Spiti, Ravi, Sutlej and their perennial tributaries originating from the Himalayas depend upon the seasonal snow cover for their discharge dependability.
Considering the importance of seasonal snow cover as a major input in controlling hydrology of river basins, HIMCOSTE director DC Rana said studies are being carried out to map seasonal snow cover in terms of its spatial distribution over different river basins during the winter season from October to April
The winter precipitation was mapped in all basins using Advanced Wide Field Sensor (AWiFS) satellite data having a spatial resolution of 56 m. “We have the information about the total snowfall that takes place during the winter season from the various observatories operating throughout the state as point information but its spatial extent reflects how much area is under snow cannot be ascertained,” Rana said.
The annual studies provide important inputs to understand the contribution of snow in different catchments to sustain the hydrology of the river basins.
The studies observed that during the early winter months of 2023-24 (October to November), all three basins Chenab, Beas, and Satluj show negative trends in the area under snow cover 2022-23. Ravi, meanwhile, shows a marginal increase in the area under snow during 2023-24 reflecting a positive trend.
During peak winter months (December to February), barring Satluj, all basins show a declining trend in the area. The Satluj shows a 2% positive trend in December from 2022-23 and 2023-24. The results obtained for the peak winter months reveal that the decline was maximum in January in all the basins with Chenab (42%), Beas (43%), Ravi (64%) and Satluj (67%) during the 2023-24 winter in comparison to 2022-23 respectively.
The snow cover in February in all the basins shows a positive trend and the area under snow increased during this period.
During March 2024, the same positive trend was observed in each basin in March. Likewise, at the beginning of the ablation period i.e., April, the winter precipitation extended to enhance the area in each basin. There is a decline of 15.39% in snow cover in the Chenab basin in comparison to 2022-23, whereas in Beas the decline was of the order of 7.65%, in Ravi the decline was 9.89% and in Satluj, the decline was of the order of 12.45% with an overall decline of about 12.72% in the entire.
“Studies conducted by the Centre on Chenab, Beas, Ravi and Sutlej based on the monthly average of the area under snow cover in each basin in 2023-24 in comparison to 2022-23, which was about 14.05% in 2022-23 winter time,” senior scientific officer climate change Surjeet Singh Randhawa said.
The higher rate of decrease in the Chenab basin reflects that winter precipitation during 2023-24 was comparatively weak. It is so as the topographic location is such that it was presumed to receive more snow because of the Western Disturbances that originates from the Mediterranean region enters through Afghanistan, Pakistan, Jammu Kashmir and then Himachal giving more precipitation in the Lahaul Spiti area before crossing the Pir Panjal range.