By Passang Norbu
HYDROELECTRICITY Most river systems in the country are glacial-fed that feed the hydropower plants, the nation’s main source of revenue.
While glaciers contribute so much to the river systems, a significant of it is dependent on the monsoons that regulate the flow of rivers and into run-of-the-river hydropower plants.
With global warming and the subsequent fears of glaciers retreating hydropower project official said building reservoirs had become all the more important.
“Reservoirs and dams that provide water storage would not only benefit hydropower generation in times of shortage but also control flood and erosion following incessant rain,” Punatsangchhu project managing director R.N Khazanchi said.
Reservoirs, therefore, he said were necessary given that run-of-the-river dams were heavily reliant on seasonal monsoon rains.
When rainfall drops dramatically during the winter months, hydroelectric output falls to below 300MW.
Today, the country generates around 1,480MW of power, nearly four times its national need of 400MW.
A major proportion of it is sold to India, that provides financing for nearly all of the ongoing hydropower constructions.
In 2005, the country exported 1,775 million units (about 67 percent of the total electricity generated) to India.
During the lean periods of the winter months, power had to be imported from India.
Returning to reservoir schemes, Khazanchi said the new upcoming hydropower projects, such as Bunakha, would have reservoir dams.
Hydropower officials, however, fear the environmental impacts that would come with the construction of reservoir dams.
But weighing the damages against the benefits of having reservoir dams, the benefits probably outweighed damages it would do.
“Reservoirs can alleviate the water shortage problem by storing excess water during the monsoon periods, which is then released during the dry seasons,” a hydropower official said.
Hydropower contributes about 45 percent of the total national revenue and constitutes about 18 percent of country’s gross domestic product.
It is estimated that Bhutan has hydropower potential of 30,000MW out of which 23,760MW has been identified and assessed to be technically feasible.
There are four major river basins, Amochhu, Wangchhu, Punatsangchhu and Drangmechhu that gush down the ridges of the country in torrents and dives into the Indian plains where it turns calm and still. .