From August 2 to 4 this month, the Dhansiri (South) behaved in an unprecedented manner. Its highest flood level (HFL) crossed its previous highest level of 79.87 at Numaligarh in Golaghat district of Assam to reach a new HFL of 80.18 metres, 31 cms above the previous one.
A report appearing in the The Assam Tribune stated that the new HFL of the river itself is a queer development, as experts are of the opinion that usually the new HFL of a river is generally a few cms higher than the previous one.
The report further stated that Himanshu Thakkar of the South Asia Network on Dams, Rivers and People, who is studying rivers and dams of South Asia, alleged that all these developments were the result of the ambitious plans of the North Eastern Electric Power Corporation (NEEPCO) to generate higher amount of power from its Nagaland-based Doyang Hydroelectric Power Plant.
He said the water level of the river also remained above the old HFL of 79.87 metres for over 60 hours, which is also unusual as rivers seldom maintain HFL for more than a day or so. The Dhansiri (South) had recorded the HFL of 79.87 metres on September 24, 1985, about 33 years back.
The district-level rainfall data of India Meteorological Department (IMD) did not record unprecedented heavy rainfall in the Dhansiri catchment in the week preceding these developments. The catchment in fact had seen deficit rainfall this monsoon. Similarly, there were no sign of such unprecedented rainfall or rising flood levels in other rivers around Dhansiri.
The Doyang hydel project’s reservoir has a gross storage capacity of 535 million cubic metres (MCM) of water and its live storage capacity varies between 370 MCM and 400 MCM as per different sources. Interestingly, the spillway of the project’s dam has a capacity to release 5,977 cubic metres of water per second (cumecs), which indicates that the Doyang dam has the capacity to bring massive flood disaster in the downstream areas if it is not operated properly.
Though the NEEPCO website does not provide any information on how the Doyang dam was operated in the days preceding the August 2-4 floods in Golaghat district areas, it has been learnt from the National Power Portal (NPP) of the Central Electricity Authority that the Doyang Project produced 45.52 million units (MUs) of power in July, 2018. This was more than three times the electricity the project is supposed to produce in July.
In the latter part of July, NEEPCO continued to generate maximum electricity in Doyang. As per NPP, the NEEPCO generated 1.67 MU on each of July 20, 24 and 25, 1.78 MU on July 26, 1.76 MU on July 27, 1.71 MU on each of July 28 and 30 and 1.70 MU of power on July 31 in Doyang. This makes it clear that the water level of the Doyang dam even on July 24 to 31, 2018 was very high to enable the NEEPCO to generate so much of electricity throughout this period.
The NPP also reveals that by design, the NEEPCO is supposed to keep water level low during the month of July so that there is minimum risk of flood to the downstream areas. However, the NEEPCO was violating that norm on a daily basis. For, NEEPCO could not have produced three times of the Doyang’s design energy without keeping the water level high in the dam, which is completely against the basic principle of flood management, said Thakkar, adding, NEEPCO should compensate all those who have suffered due to floods in Golaghat district this month.