A race against floods: From 8 to 36 hours

Two thousand six hundred villages were submerged in the 2011 floods in Odisha.

UK AID has assisted the Government of Odisha develop a flood forewarning system that will allow an additional 36–72 hours to evacuate people and property to safer locations. “I was watching from the embankment in Nimapara in 2008. The water was rising minute by minute. There was no formal communication, no warning. At midnight, there were rumours of a breach which led to total panic. Villagers started to hoard potatoes. Shops were shut down,” said B.M. Acharya, Director, Hydrology and Water Planning, Government of Odisha.

“The flood came at three o clock. The dam’s capacity was 9-11 lakh cusecs of water; the amount of water exceeded 15 lakh cusecs. Property, cattle and homes were inundated. We lacked a sophisticated flood forecast system to prevent this catastrophe.”

This is not a one-off event. Mahanadi river basin in Odisha is historically notorious for its floods. So much so that the river is called ‘the sorrow of Orissa’.

Heavy rainfall in the upper catchment area causes severe flooding in the downstream districts of Odisha. As recently as 2014, floods in the Mahanadi have affected over 1500 villages and almost 1.8 million people resulting in damages of over INR 5 billion.

Climate change is adding insult to injury. The State Water Plan prepared by the Government in 2004 observes “variability of monthly rainfall is increasing which means that rainfall is concentrated in a particular period”. These are worrying signs. Flood discharge between 12 and 14 lakh cusecs was recorded 10 times at Naraj district after the construction of the dam, though at the time the dam was built, it was considered that such a high level of flood would arise only once in 1000 years.

A systemic overhaul

In 2014, there was a growing sense of realisation within government circles that they needed to develop an early warning system against floods. “We (Department of Water Resources) decided to take ACT’s help in developing this early warning model. We were thinking of 2050,” said Muralidhar Panda, Deputy Director Flood Forecasting and Flood Risk Management, Department of Water Resources, Government of Odisha. He speaks the language of a technical expert in early warning systems and seems proud of the progress they have made since 2014.

The intent was there, but the knowhow was lacking. During the same period, UK AID was pushing for climate proofed growth in Odisha through the Action on Climate Today (ACT) initiative. Developing a robust flood forecasting model was a perfect fit.

ACT Team Leader, Soumik Biswas, recalled: “The Government knew they had to do something. They couldn’t sit idle, but they didn’t know where to go. UK AID could provide them with the best available technical support without going through tedious and time consuming processes involved in the government machinery. You have to think of the practicality.”

“It immediately appealed to me because of the major impact it would have on the people. We cannot avoid the damages altogether, but if we increase the warning time by even eight extra hours it means people can move cattle, valuables and even property. They can rebuild their lives.”

The system needed an overhaul: A move from a reactive model based on the observed rainfall of the previous day to a proactive one based on the projection of rainfall for the next 3 days.

SWAT model

It was a risky business. No one knew how the new model was going to perform. There were cost and time implications. Reputations were at stake. There was no shortage of scepticism within sections of the Water Resources Department. Developing the model wasn’t enough. Add to that the need for unprecedented coordination and the disaster management agencies for effectiveness and overall impact. All the pieces had to come together to become greater than the sum of its parts.

Different models were carefully analysed for suitability before selecting the Soil and Water Assessment Tool (SWAT). The SWAT model is a spatially distributed, physically based model. It requires site specific information about weather, soil properties, topography, vegetation and the land management practices being followed in the basin.

“Getting the data, the right data and at the right time was the biggest challenge. We had to spend a lot of time to get the data that we wanted. Even when we got the data, extra efforts were necessary to sanitise the data properly and exclude outliers or simply impossible observations,” said Soumik.

The scope of the work involved:

  1. Identifying the departments responsible for flood planning and real-time response to flooding and their minimum information needs.
  2. Providing indicative costs of producing a river basin modelling system.
  3. Building the capacity (institutional, technical and financial) of relevant government planning and implementing agencies.
  4. Testing and refining the model at the ground level.

All the villagers, more than 500 of them, live and sleep here during the floods

ACT knocked on the doors of different departments like the Central Water Commission, Indian Meteorological Department, and Water Resources for data. Subsequently, ACT sanitised the data to be able to begin the model design. After six months of work, in November 2015, ACT could convince the Water Resources department that developing a model to suit the department’s requirement is possible through SWAT.

After being approved, the work on development and validation began in full force. It had to meet two separate and uncompromising criteria of providing a good projection with respect to time and volume of flood. Validations were performed in 23 locations. The model showed strong validations in all but three locations and was more accurate in predicting flows into Hirakud dam than both Central Water Commission’s as well as the government’s own predictions. At that point (December 2016) the Principal Secretary gave the nod to launch the model.

On the ground

In flood-prone Tikhiri village, located on the banks of Mahandai, people are unaware of these developments. However, they remember the devastation that floods cause almost every alternate year. Akshay Kumar’s daughter caught a fever during the 2011 floods. “We were cut off from everyone for ten days. There was no medicine available. We rubbed Neem leaves on her neck and used other ayurvedic measures,” he said.

The school was shut down, electricity was off and they slept on the roof of a former government revenue office – waiting for the water level to recede. It took them one month to rebuild their thatched huts. Rebuilding lives takes much longer and then comes another flood.

When asked, “What would you do if you received a warning 36 hours in advance?”, the answers came thick and fast. “We would harvest crops first. It would still be impossible to save everything, but we would call our relatives and try to cut and store as much as possible,” said Sanjoy Meher. Another farmer added: “We would send the children and women away to safer locations.” “I would save drinking water,” said a labourer. He added: “During the previous floods, my daughter asked me for biscuits and I had nothing.”

Conclusion

ACT conducted an exposure training for operators at the Hirakud dam in December 2016. Harmohan Pradhan, Chief Engineer, Upper Mahanadi Basin, who is responsible for the dam operation, agreed with the need for an overhaul. The model will now be formally launched by the Chief Minister in April. They say this monsoon season is going to bring adequate rainfall. The model is ready for baptism by flood.

 

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