While Bihar Chief Minister Nitish Kumar has been blaming the Farakka barrage for the flooding in Patna and elsewhere in the state, it is now getting increasingly clear that sudden release of large volumes of water from Bansagar dam in Madhya Pradesh could have been the main reason for the worst “man-made floods” in the country in several years.
Bansagar, about 50 km south of Rewa town in Madhya Pradesh, is a multi-purpose irrigation-cum-hydroelectric project on Sone river that flows through eastern Uttar Pradesh and south Bihar before meeting Ganga at Patna. The reservoir has a capacity to store over 5 billion cubic metres of water.
With central India, particularly Madhya Pradesh, having received very good rainfall this season, water level at the reservoir was steadily rising from the first week of July. Throughout August, water level in the reservoir was well above 336 m, very close to the full reservoir level of 341.64 m. With more rains forecast later in the month, it was expected that water would be slowly released from the reservoir to avoid a breach.
However, Madhya Pradesh authorities hoarded the water till the level crossed 341 m on August 18. Information on the website of state’s water resources department shows that after that mark was reached, the dam released as much as 14,08,571 cusec of water between August 18 and August 20. Prior to that, water was released only once in the previous 10 days. The sudden release of huge volumes of water flooded downstream areas which were already having good rain during that time.
“If water had been released in phases over a longer duration, this kind of flooding could have been avoided,” a water official in central government said.
“It is difficult to say whether there would not have been flooding in Bihar in the absence of such massive release of water in a short period, but the situation would definitely have been much better. Some amount of flooding is definitely a result of good rainfall in Himalayan region in the last two weeks which have brought waters in rivers like Ghagra or Rapti that flow into Bihar,” he said.
Another official said states tend to hoard water in their reservoirs due to uncertainties in rainfall in future. However, this time the forecast by Indian Meteorological Department had been repeatedly predicting continued good rainfall over central India.
Data shows that Bansagar dam released 59046 cusec of water at 8 am on August 18, immediately after the water level crossed the 341 m mark. It released another 1,42,672 cusecs at 5.30 pm. The next morning, it discharged a massive 5,57,906 cusecs at one go. The dam had opened 16 of its 18 gates to let the water flow out. On August 20, it released even more water, 6,48,947 cusecs in three tranches. Some water was released Tuesday and Wednesday as well.
Despite the discharges, the water levels in the Bansagar reservoir has been kept well above the 340 m mark. On Wednesday, it was at 340.9 m.