Flawed data doomed states

Hyderabad
Oct. 12: Irrigation experts and policy makers were dumbstruck when they found that about 14,000 square kilometres in seven districts of both Andhra Pradesh and Karnataka are not covered by rain gauging equipment.
This proved fatal in the recent floods, which surged quickly to submerge Kurnool, Mahbubnagar and Mantralayam. Some 200 mm of rain fell on September 29 alone in 7,000 square km of area below the Jurala and Roja, where no rain gauging facility is available.
This changed the complexion of the flood. The unaccounted water proceeded towards Srisailam. Twelve districts in Andhra Pradesh, Maharashtra and Karnataka received 400 mm average of rainfall on four consecutive days starting from September 29. This water also joined the flow to reach the Srisailam dam. Though there are rain gauging centres at some places for the economics and statistics wing, the information is never shared with the Central Water Commission (CWC). “Unfortunately the CWC did not receive information about the flash rains and their impact on the overall inflow as it does not have rain gauging equipment downstream of Jurala and Roja,” confirmed Mr Rehman, the engineer-in-chief, irrigation department.
The CWC and state irrigation department thus got no warning of the impending flood until September 30, when it descended on them. According to the Indian Meteorological Department (IMD), the rainfall received during those five days was the highest known in the country since 1901. The river Krishna has never witnessed such inflows in its known history. In 1903, the river received 10.5 lakh cusecs inflow at the Prakasam whereas in the recent floods it received 10.9 lakh cusecs over just three consecutive days.
The Srisailam dam was built to discharge 13.5 lakh cusecs maximum, but was forced to discharge 24.8 lakh cusecs of water.
What would have happened if the Srisailam and Nagarjunasagar dams and the Prakasam barrage were not there? If the 25 lakh cusec inflow was let out in the absence of these dams and barrages, most of Krishna district including Gudivada, Tenali, and Repalle towns would have been submerged. Villages near the river Krishna in Nalgonda, Mahbubnagar, and Kurnool would also have been submerged,” said a senior official in the irrigation department. The CWC’s failure to provide accurate data about the river inflow only aided nature’s fury. The CWC report given to the Kurnool Collector on October 1, at about 4 pm, sounded the alert that the Tungabhadra was set to receive an “historical flood”. However, in a report sent to the irrigation department, the CWC said that only 26,000 cusecs would reach the Tungabhadra dam.
This imperfect information proved costly to the residents of the temple town where the highest number of deaths was recorded.


Source::DC