Less snowfall in Sutlej basin sounds alarm

Bhanu P Lohumi

Tribune News Service

Shimla, May 13

After mid-hill areas, the process of climate change has started impacting the higher hills and if the declining trend of snowfall in the catchment of the Sutlej is any indication, it could have serious repercussions on the hydropower sector and irrigation and drinking water schemes in the catchment area.

The Sutlej is the longest snowfed river (320 km) flowing through Himachal, having a catchment area of 20,000 sq km, and a large number of hydro projects have come up or are under execution in the Sutlej basin.

As per the latest study conducted by scientists of the Meteorological Department, the average snowfall during winters, (November 1 to April 30) has been decreasing by an appreciable 4.1 cm annually over the past three decades.

The maximum decline in the snowfall of 2.1 cm was observed in March-April, followed by 1.3 cm in November-December and 0.7 cm in January-February. The maximum quantum of snow was received during February and March, which accounted for 56.5 per cent of the total snowfall during the season.

The study of the 30-year snowfall data of the Sutlej catchment, conducted jointly by Dr Manmohan Singh, Dr SC Bhan, OP Singh and Rajeev Bansal, revealed that the decreasing tendency was higher in the early and late part of the season and the snowfall in the middle part was relatively stable.

All months are showing the decreasing tendency, delay in setting in and early ending of snowfall. Further, the snow season has been commencing late by 5 to 7 days per decade, showing compression in the snowfall season.

The analysis indicated that besides hydropower projects, it would have a potential adverse impact on the river flow and agricultural/horticultural production in the state and suggested extensive studies before arriving at final conclusions regarding the impacts.

The trend is a cause for concern for power producers as the Sutlej has the highest power potential of about 11,000 mw and also the highest number of operational power projects, including, 1200 mw Karcham Wangtu, 300 mw Baspa , 1500 mw Nathpa Jhakri, 800 mw Kol Dam and 120 mw Bhabha project, have come up upstream the Bhakra Dam project.

Besides Kol Dam, all projects are run-off-the-river schemes with no storage and as such the hydropower generation will be affected during summers. The shortening of snow season will also result in a decline in quantum of snow which is stored in high hills in the shape of glaciers.

The irrigation and drinking waters schemes of all major towns and villages in the catchment area are based on the Sutlej and its tributaries and the shortage of water during summers for irrigation channels and drinking water would be more acute.

The receding snowfall will seriously impact the apple crop as the number of cooling days will be reduced and snow, known as white manure for apple, will not be available, horticulture experts say.

As the 70 per cent area under agriculture is rainfed and mid and lower hills reel under scorching heat in summers, the agriculture production will be badly hit in the event of delayed or deficient monsoon rain.