GUWAHATI, Aug 31 - IIT Gandhinagar researchers have suggested careful consideration of the uncertainties in climate change-related precipitation projections, along with robust and comprehensive adaptation strategies to meet the challenges of climate change, while planning future hydropower projects. The researchers carried out a study on the probable impacts of climate change on seven large hydropower projects of the country.
Himanshu Thakkar of South Asia Network for Dams, Rivers and People (SANDRP), who has been studying the rivers of South Asia for decades, said, “The suggestion of the Gandhinagar IIT researchers is equally relevant for the hydroelectric projects of NE India. Because, climate change is significantly impacting the rainfall pattern and climate of Eastern Himalayas too.”
While carrying out the study, the Gandhinagar IIT researchers observed that during the past about six decades, between 1951 and 2007, seven large hydropower projects of the country experienced a significant warming and a decline in precipitation and stream flow. However, all the hydropower projects were projected to experience a warmer and wetter climate in the future, they said, in the article – ‘Projected Increase in Hydropower Production in India under Climate Change,’ published in the journal Scientific Reports.
It needs mention here that India is the seventh largest hydroelectric power producer in the world and hydropower is the second largest contributor to the Indian power sector. The most significant hydropower potential in India exists in the three major trans-boundary river basins – the Ganga, the Indus and the Brahmaputra.
The Gandhinagar IIT researchers, who included Syed Azhar Ali, Saran Aadhar, Harsh L Shah and Vimal Mishra (leader of the team) of the Civil Engineering Department, are of the opinion that these basins have experienced substantial changes in precipitation and air temperature that affected water availability for hydropower generation. Since hydropower production and its potential depend on stream flow, it is sensitive to climate change, they said.
The researchers carried out their study on Nathpa Jhakri, Bhakra Nangal, Srisailam, Nagarjuna Sagar, Hirakud, Sardar Sarovar and Indira Sagar. These large reservoirs are located on the four major basins – Indus, Krishna, Mahanadi and Narmada. The Nathpa Jhakri and Bhakra Nangal reservoirs are located on the River Satluj, which flows from the snow-dominated upper part of the Indus basin.
Most of the catchments of the large reservoirs are projected to experience a substantial warming under the projected future climate. Consistent with previous studies, the highest warming is likely for Nathpa Jhakri and Bhakra Nangal where the annual mean temperature is projected to increase by more than 6.25 plus-minus 1.5 degree Celsius by the period between 2070 and 2099 under the Representative Concentration Pathway (RCP) 8.5 scenario.
They projected the multi-model ensemble mean annual average temperature for the future period to rise between 1.38 and 6.32 degree Celsius in the catchments upstream of the other reservoirs.
All the seven reservoirs were projected to experience a wetter (up to 18 per cent increase) scenario in the projected future climate. Under the RCP 8.5, Nathpa Jhakri and Bhakra Nangal are projected to experience 17.04 plus-minus 20.76 per cent and 15.30 plus-minus 20.16 per cent increase in mean annual precipitation by the end of 21st century.
The projected increase in stream flow for the reservoirs located in central and south India can be attributed to the increase in the monsoon season precipitation under the future climate. Stream flow and water availability in India is largely dominated by the changes in the monsoon season precipitation and projected warming plays a secondary role, said the Gandhinagar IIT researchers.