The seasonal snow cover of Chenab, Beas, Ravi and Satluj river basins in Himachal Pradesh has declined by 10 per cent in 2022-23 compared to 2021-22, according to a study by the state's Centre on Climate Change.
The study of snow cover is an important input to understand its contribution in different catchments to sustain the hydrology of river basins. Himachal Pradesh receives winter precipitation in the form of snow at higher altitudes and most of the major rivers in the state such as Chenab, Beas, Parvati, Baspa, Spiti, Ravi and Satluj, and their perennial tributaries originating in the Himalayas depend upon seasonal snow cover for water discharge, the study said.
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Mapping the winter precipitation in all the river basins namely Chandra, Bhaga, Miyar, Beas, Parvati, Jiwa, Pin, Spiti and Baspa was done using advanced wide field sensor satellite data from October 2022 to April 2023, Director-cum-Member Secretary of the Himachal Pradesh Council for Science, Technology and Environment (HIMCOSTE), D C Rana, said on Saturday.
"Ten per cent decline was witnessed in the four basins of Chenab, Beas, Ravi and Satluj based on the monthly average of the area under snow cover in each basin in 2022-23 in comparison to 2021-22," said the study on variation in snow cover of river basins.
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Snowfall during 2022-23 was estimated and analysed with reference to the average value of the total area under snow in each month from October to April, it said. Based on the analysis, it was observed that the decline was 0.39 per cent in Chenab basin, 6.9 per cent in Beas, 22.42 per cent in Ravi and 14.61 per cent in Sutlej in 2022-23 in comparison to 2021-22 in terms of the total spatial distribution of the snow cover, the study said.
Himachal Pradesh Chief Secretary Prabodh Saxena said the study pointed out that most of the glaciers are losing mass. Besides this, a large shift has also been observed in the snowfall patterns during winters affecting the river water discharged during the peak summer season, he said.
No snowfall was witnessed in Shimla this time which seems to be a major change in the weather patterns and if this continues, water shortage would be a problem in the coming years, Saxena said. He said steps such as introduction of e-vehicles and shifting to renewable energy to reduce greenhouse gases emission to check rise in temperature is the need of the hour.
The study said following early snowfall in October and November in 2022-23, positive trends were witnessed in Chenab and Beas basins, whereas Ravi and Satluj basins showed decrease in area under snow cover.
During peak winter months (December-February), all four basins -- Chenab, Beas, Ravi and Satluj -- had negative trends in comparison to corresponding periods in 2021-22, it said and added that the worst-affected basins were Ravi and Satluj.
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The analysis of month-wise data revealed that during October, Chenab basin showed a decline of about 36 per cent, Ravi 54 per cent and Satluj about 27 per cent. Beas showed three per cent increase in snow cover in 2022-23 compared to 2021-22, the study noted.
In November, Chenab and Beas basins reflected five per cent and 21 per cent enhancement in comparison to 2021-22, whereas Ravi and Satluj showed a decline of three per cent and 22 per cent. In December, there was a decline of about 56 per cent in Satluj basin and 10 per cent in Chenab basin as compared to 2021-22.
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The study said the four basins showed a decline in January 2023. The decline was five per cent in Chenab, 16 per cent in Beas, three per cent in Ravi and 38 per cent in Satluj. During February, the decline was four per cent in Chenab, 32 per cent in Beas, 12 per cent in Ravi and 17 per cent Satluj basins.
Declining trend continued in March 2023 also and Chenab, Beas, Ravi and Sutlej basins witnessed a decrease of two per cent, five percent, seven per cent and four percent respectively compared to 2021-22. In April 2023, however, the area under snow in Chenab basin was 22 per cent, Beas 39 per cent, Ravi by 54 per cent and Satluj 29 per cent, the study said.
