Snow cover up by 25.16% in river basins

Snow cover up by 25.16% in river basins
Assessment of spatial distribution of seasonal snow cover during 2018-19 in Himachal Pradesh using space data has revealed that there is considerably increased snowfall in Himachal Himalaya.

The analysis has been made from the AWiFS satellite data for 2018-19 for assessing the total area under snow cover during the period October to March and its temporal analysis with that of the monthly averaged values of the total area under snow 2017-18. As a whole total increase of 25.16% in the area under snow cover has been observed in Himachal Pradesh in 2018-19 in comparison to the total area during 2017-18.

Himachal Pradesh receives winter precipitation in the form of snow at the higher altitudes. About 1/3rd of the total geographical area of the state remains under thick snow cover during winter season. Most of the major rivers like Chenab, Beas, Parvati, Baspa, Spiti, Ravi, Satluj and their perennial tributaries originating from the Himalayas depend upon the seasonal snow cover for their discharge dependability. Besides this, the snow cover also helps in controlling the accumulation and ablations patterns of the glaciated regions in the State.

Considering the importance of seasonal snow cover as a major input in controlling the hydrology of the river basins, seasonal snow cover assessment in its spatial distribution is being carried out in different river basins in Himachal Pradesh during the winter season from October to March.

During the last winter that is 2018-19, it was a general perception that the winter precipitation was of higher magnitude in comparison to the preceding year. Keeping this into consideration, total area under snow cover was estimated using satellite data during 2018-19 and was compared with that of the values estimated during the period 2017-18 in Himachal Pradesh.

The study was conducted by the Himachal Pradesh State Centre on Climate Change under the aegis of HO Council for Science, Technology and Environment and Space Application Centre, ISRO, Ahmadabad.

Based on the satellite data it has been observed that by and large all the river basins of Himachal Pradesh show an increased percentage change in their area under snow reflecting that 2018-19 is the year of exceptionally heavy snowfall in all the basins of the state.

A basin-wise analysis from October to March in 2018-19 and its comparative analysis with that of 2017-18 reveals that, in Chenab basin, maximum increase is of the order of about 183.2% in the month of October, whereas November shows an increase of about 45.1% and December, January shows an increase of about 17.4% and 4.2% respectively and February, March shows about 7.2% and 5.3% increase in comparison to 2017-18.

Ravi basin shows an overall increase of about 411.2% in October, while in November it shows an increase of about 93% in 2018-19 whereas January, February and March show 38.3%, 96.1% and 51.2% respectively. In December, total snow cover has decreased by 11.4% (2018-19) in comparison to 2017-18.

Beas basin also shows a more or less similar trend of increase in October by about 106.45%, whereas November, February and March shows of 52.66%, 31.46%, 30.69% respectively in 2018-19, and there is a reduction of 16.18 % in the month of December (2018-19).

In Satluj basin it is concluded that during 2018-19 there is considerably increased snowfall in October (185.2%) and November (75.2%). Whereas December and January months showing reduction of 0.95% and 0.05%. and the increase of the order of 14.9% and 18.1% respectively in February and March.