As people come to terms with the unexpected floods that played havoc in Kerala, it is widely believed the abrupt opening of several dams, and that too without warning, proved disastrous, especially in Wayanad and the worst-hit zones like Chalakudy, Kuttanad and Chengannur.

The sudden opening of the Banasura Sagar Dam contributed to the deluge in Wayanad district in the northeast of the state. Even when the four-decade-old reservoir across a tributary of the pivotal Kabini river impounds water, monsoon rains annually inundate the downstream region comprising Panamaram, Venniyod, Kottathara, Kurumani, Vellamunda and Pandijarathara. This time, the situation got worse because authorities lifted the sluice gates of the dam, which is built across the Karamanathodu on the Western Ghats, 20 km from Kalpetta town. The result was a double disaster.

Already facing the typical June-August inundation, the residents of the hilly terrain, along the course of the river downstream of Banasura Sagar experienced a sudden swell in the water levels around them. As the turbulent gush swallowed small houses on both sides of its way, people rushed to structures that had two floors or were on relatively upper regions. The roads got battered, necessitating major repair to resume smooth surface transportation.

Banasura Sagar, with a full reservoir level of 775.6 metres, has four shutters. Last month, when rains began to thicken, three gates were opened on July 15 to a height of 20 cm. That step of the operation was carried out after informing the public downstream, but none of the subsequent moves in the sequence happened after giving prior alert to anyone, according to residents. Last week, when pressure intensified on the walls of the dam, which has a maximum capacity of 209 million metre cube, the fourth sluice gate too was lifted — all of them to a height of 290 cm. That led to massive inundation downstream, completely submerging several single-storey houses. None of the inhabitants were told about the letting out more waters during any of these stages.

Later, one day, the shutters were downed to 80 cm, but by night it was again raised back to 90 cm. Prior to it, the public was served with no warning, customarily through loudspeaker announcements, or bulletins on radio or television. In fact, dam authorities, it turned out, didn't inform even the local village officer or the district collector.

This unilateral operation invited a surge of wrath from local people, triggering a controversy and prompting authorities to resume the convention of issuing prior alerts. Currently, on Wednesday, Banasura Sagar has one of its four shutters up - by 10 cm.

So, what happened in between? The Kerala State Electricity Board (KSEB) that owns and runs the reservoir says it had it had issued the alert on a WhatsApp group of the Disaster Management Authority. Whatever, in a single day the dam had accumulated rainwater measuring 562 mm, which translated to a tenth of its total holding capacity. This inflow was much more than anticipated, according to KSEB assistant executive engineer P Manoharan. He attributes it to landslips in the vicinity that brought an unexpected volume of water into the river around the dam.

Upper Sholayar, Parambikulam

Down south, the hill tracts of Palakkad and Thrissur districts also experienced similar catastrophe owing to laxity by authorities of two major dams amid heavy rains. The Parambikulam and Sholayar reservoirs are under the control of the neighbouring state of Tamil Nadu. Its government alerted the Kerala people only hours before opening their shutters. While people got into deep trouble, the freed waters swelled up the KSEB-operated Peringalkuthu dam across the Chalakudy river in Thrissur district. The whole of Chalakudy town, 31 km south of the district headquarters of Thrissur, went under water.

No warning in Pathanamthitta

Further southward across the state's eastern stretch, Pathanamthitta was not under red alert even on August 14 night and by the next day morning the arterial Pampa had swelled several swathes of the district. Several houses had been inundated with water, marooning thousands of people. This is when protocol insists that a red alert must be issued for people to vacate their homes 24 hours in advance. Had authorities stuck to the rule, many families could have got the time to vacate homes.

Review on

In the state capital of Thiruvananthapuram, the government said it would probe into the alleged flaws in the operations of opening dam shutters vis-a-vis informing the public. The moves comes in the wake of complaints from people downstream Banasura Sagar besides 51-year-old Sabarigiri dam built across a Pamba tributary in Pathanamthitta district. The initial reports show major mistakes in the way the operations were carried out.

The opening of reservoirs ideally go by rules stipulated by the National Disaster Management Authority (NDMA) formed in 2005. The shutters can be lifted only with the order from the district collector, who is the local authority of NDMA. (The only exceptions in Kerala are with two big reservoirs of Idukki and Mullaperiyar.) The clearance to opening of the shutters comes on the basis of the request filed by official in charge of the dam, showing the seriousness of the situation. The lifting of sluice gates also warrants sending prior information to the district police chief. The dam operates under the executive engineer and his/her deputy if the hydel project is owned by the electricity or irrigation department of the state government.

When it comes to Mullaperiyar on Kerala’s eastern border, it is the Supreme Court that gives permission on opening the shutters of the dam owned and operated by the Tamil Nadu government. As for Idukki, the decision on opening the dam rests with a council formed under the Kerala chief secretary. The panel comprises top officials of the state’s departments of home, finance and health.